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Cummins/Onan 5.5 HGJAD Troubleshooting

Cummins/Onan 5.5 HGJAD troubleshooting: 147 fault codes and 23 symptom-cause-remedy entries from the manufacturer's own service documentation.

Cummins/Onan 5.5 HGJAD — full specs, parts & maintenance.

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Troubleshooting

170

Fault codes

CodeMeaningCauseRemedy
2Low oil pressure faultLow/high oil level, faulty switch, faulty oil pressure relief valve, fault oil pumpVerify that Last Fault is FC 2: Yes, continue diagnosis; No, troubleshoot actual last fault; Measure oil level: add or drain oil as necessary; Disconnect genset control P1 connector, verify P1 pins are fully inserted and inspect pin condition per PSB–676: insert, repair or replace pins as necessary; Reconnect P1 connector and test run genset for fault occurrence: repair or replace pins in connector as necessary; Measure continuity change across start/stop switch between rest and under simulated pressure: replace switch as necessary; HGJAB, C – Measure continuity between ground and P1–13: repair or replace harness as necessary. HGJAA, D, E, F – Measure continuity between ground and P1–6: repair or replace harness as necessary; Measure oil pressure with mechanical gauge: repair or replace relief valve and oil pump as necessary
3Service check faultAny Two-Digit Fault CodeVerify that Last Fault is FC 3: Yes, continue diagnosis; No, troubleshoot actual last fault; While LED is flashing three times press stop once (1 second duration): trouble shoot Two-Digit Fault Code
4OvercrankFaulty switch, faulty external start command, fuel supply, air fuel mixture, exhaust system, wire connections, starter, ignition systemVerify that Last Fault is FC 4: Yes, continue diagnosis; No, troubleshoot actual last fault; Measure for continuity change across start/stop switch between neutral and start position at switches and P1 connector: replace switches as necessary or disconnect external start device if so equipped; Disconnect genset control P1 connector, verify P1 pins are fully inserted and inspect pin condition per PSB–676: insert, repair or replace pins as necessary; Reconnect P1 connector and test run genset for fault occurrence: repair or replace pins in connector as necessary; Verify engine rotation manually: repair engine damage as necessary; Measure DC voltage at starter during start attempt: repair wire connections, replace start solenoid and starter as necessary; Check air filter cleanliness; replace air filter as necessary; Check for blocked or damaged exhaust system: repair or replace exhaust components as necessary; All Gasoline Models: Vapor lock may occur in high ambient temperatures: operate in ambients at less than 120°F; verify proper installation to prevent air recirculation; correct as necessary. Measure steady DC voltage at fuel pump while genset is cranking: repair wiring as necessary. Try to start genset on shop fuel supply: verify tank level and fuel line condition in vehicle; All Gasoline Carburetor Models: Verify carburetor altitude setting: readjust as necessary. Verify choke operation, setting, linkage, vacuum pull off assembly and sustain valve: readjust, repair or replace as necessary. Measure fuel pump pressure/flow: replace fuel filter or fuel pump as necessary. Inspect carburetor butterfly for binding: replace carburetor as necessary; All Gasoline EFI Models: Inspect throttle body for binding or damage: replace as necessary. Measure fuel pump pressure/flow: replace fuel filter, pressure regulator or fuel pump as necessary; Propane Models: When ambient temperatures are less than 40°F vapor-withdrawal Propane tanks should be at least half full to provide proper vaporization rate. Propane having more than 2.5 percent Butane will not vaporize in ambients at less than 32°F; use HD–5 grade Propane. Measure steady DC voltage at fuel solenoid while genset is running; repair wiring as necessary. Verify clear vent hose. Run genset on shop fuel supply; verify tank level and fuel line condition in vehicle. Check genset fuel lines for damage: replace fuel line as required. Measure regulator lock off pressure; Check governor, actuator, linkage and spring for debris, damage and looseness: readjust and repair as necessary; Verify that spark plug cables are secure on spark plugs
13AC voltage S1–S2 less than 108 VAC for 5 continuous secondsGenset loads, Inverter/Charger, wire connections, generator drive system, windings, AC sense transformer, windingsVerify that Last Fault is FC 13: Yes, continue diagnosis; No, troubleshoot actual last fault; Measure AC voltage; Measure AC voltage in and out of sense transformer (if so equipped): repair wire connection, replace sense transformer as necessary; Measure AC frequency while changing engine rpm to determine if frequency response matches engine rpm response: repair damaged generator drive system as necessary; Cycle loads to determine if a particular load will cause fault: diagnose faulty load as necessary; Determine battery charge rate (typical default is 80 percent): if adjustable reduce to 30 percent; Verify balanced loads in 120/240 VAC applications: balance loads within 10 percent line–to–line as required; HGJAD only – Run genset in Engine Run Only mode and externally excite field F1–F2 with 12 VDC or 24 VDC and measure main and quadrature winding AC output; Non EFI – If the genset will not stay running measure genset frequency, quadrature winding and main winding voltages using Break-Out Tool 420–0603 and Instruction Sheet R1098; Remove connector P1 from control and re-install and try to start genset: inspect, repair or replace P1 connector pins as necessary; Measure field, quadrature and main winding resistance: clean slip rings, replace brushes, repair harness and replace rotor or stator as necessary; Measure field, quadrature and main winding resistance to ground: clean slip rings, replace brushes, repair harness and replace rotor or stator as necessary; Measure field, quadrature and main winding resistance to each other: clean slip rings, replace brushes, repair harness and replace rotor or stator as necessary; Check brush alignment per PSB-682a; Dealers contact Distributor for technical support, Distributors contact factory for technical support
14OverfrequencyGenset loads, Inverter/Charger, engine governor function, fuel supply, air fuel mixture, exhaust system, choke, demand regulator, carburetor, generator drive system, generator windings, ignition, wire connectionsVerify that Last Fault is FC 14: Yes, continue diagnosis; No, troubleshoot actual last fault; Measure AC current while running genset with vehicle loads: identify faulty or short cycling loads; Determine battery charge rate (typical default is 80 percent): if adjustable reduce to 30 percent; Measure genset load capability with shop load bank (derate for altitude and temperature as necessary); Measure genset frequency and droop while running; Measure AC frequency while changing engine rpm to determine if frequency response matches engine rpm response: repair damaged generator drive system as necessary; Disconnect genset control P1 connector, verify P1 pins are fully inserted and inspect pin condition per PSB–676: insert, repair or replace pins as necessary; Reconnect P1 connector and test run genset for fault occurrence: repair or replace pins in connector as necessary; Check governor, actuator, linkage and spring for debris, damage and looseness: readjust and repair as necessary; Measure field, quadrature and main winding resistance: clean slip rings, replace brushes, repair harness and replace rotor or stator as necessary; Measure field, quadrature and main winding resistance to ground: clean slip rings, replace brushes, repair harness and replace rotor or stator as necessary; Measure field, quadrature and main winding resistance to each other: clean slip rings, replace brushes, repair harness and replace rotor or stator as necessary; Check brush alignment per PSB-682a; Verify that spark plug cables are secure on spark plugs: reconnect or replace as necessary; Inspect ignition kill leads in harness and at connector P1: repair or replace lead, terminal or pins as necessary; Test Magnetos: Disconnect Connector P1. Connect positive(+) meter lead to chassis ground. HGJAA, D, E, F – Measure continuity to negative lead at pin P1–4 and P1–5: replace magnetos as necessary. HGJAB, C – Measure continuity to negative lead at pin P1–15 and P1–20: replace magnetos as necessary; Measure spark plug gap: set gap or replace spark plugs as necessary; Verify ignition spark condition; Inspect spark plug lead, kill lead terminal at magneto and measure magneto air gap: replace terminals, set gap or replace magnetos as necessary; Measure temperature of air intake and temperature rise across genset; remove blockage or prevent air recirculation; Dealers contact Distributor for technical support, Distributors contact factory for technical support
17Fuel pump faultWire connections, harness leads, faulty fuel pumpVerify that Last Fault is FC 17: Yes, continue diagnosis; No, troubleshoot actual last fault; Verify fuel pump operation in prime mode, if pump operates fault condition has been cleared verify harness connections, no further troubleshooting; HGJAA, D Check continuity across fuse F1; Disconnect genset control P1 connector, verify P1 pins are fully inserted and inspect pin condition per PSB–676: insert, repair or replace pins as necessary; Reconnect P1 connector, prime genset to verify pump operation and test run genset for fault occurrence; Measure continuity between E2 fuel pump leads; replace terminals or fuel pump as necessary; Measure voltage between fuel pump E2 + and ground while priming; replace terminals, harness leads or control as necessary
19Governor actuator (EFI only)Wire connections, P1–17, governor actuatorVerify that Last Fault is FC 19: Yes, continue diagnosis; No, troubleshoot actual last fault; Disconnect genset control P1 connector, verify P1 pins are fully inserted and inspect pin condition per PSB–676: insert, repair or replace pins as necessary; Reconnect P1 connector and test run genset for fault occurrence: repair or replace pins in connector as necessary; P1–17 open to ground on EFI Models: ground lead as required for carburetor configuration; Verify actuator function by applying DC voltage to terminals: replace actuator as necessary; Measure resistance between actuator terminals; repair or replace connections as necessary, replace governor actuator; Measure continuity between P1–28 and actuator lead; repair or replace terminals and leads as necessary; Measure DC voltage at actuator while starting: replace controller as necessary
22Governor actuator overload (EFI only)Genset loads, Inverter/Charger, wire connections, fuel supply, air fuel mixture, exhaust system, governor actuator, ignition systemVerify that Last Fault is FC 22: Yes, continue diagnosis; No, troubleshoot actual last fault; Measure AC current while running genset with vehicle loads: identify faulty or short cycling loads or reduce vehicle loads as necessary; Determine battery charge rate (typical default is 80 percent): if adjustable reduce to 30 percent; Measure genset load capability with shop load bank (derate for altitude and temperature as necessary); Measure AC frequency and droop while running; Measure AC frequency while changing engine rpm to determine if frequency response matches engine rpm response: repair damaged generator drive system as necessary; Disconnect genset control P1 connector, verify P1 pins are fully inserted and inspect pin condition per PSB–676: insert, repair or replace pins as necessary; Reconnect P1 connector and test run genset for fault occurrence: repair or replace pins in connector as necessary; Check air filter cleanliness; replace air filter as necessary; Check intake manifold and gaskets for air leaks: tighten fasteners and replace gaskets and manifold as necessary; Check for blocked or damaged exhaust system: repair or replace exhaust components as necessary; Measure fuel pump pressure/flow: replace fuel filter, pressure regulator or fuel pump as necessary; Verify actuator function by applying DC voltage to terminals: replace actuator as necessary; Check throttle body for binding; inspect spring for dirt and debris: clean spring, replace throttle body as necessary; Verify that spark plug cables are secure on spark plugs: reconnect or replace as necessary; Inspect ignition kill leads in harness and at connector P1: repair or replace lead, terminal or pins as necessary; Test Magnetos: Disconnect Connector P1. Connect positive(+) meter lead to chassis ground. HGJAA, D, E, F – Measure continuity to negative lead at pin P1–4 and P1–5: replace magnetos as necessary. HGJAB, C – Measure continuity to negative lead at pin P1–15 and P1–20: replace magnetos as necessary; Measure spark plug gap: set gap or replace spark plugs as necessary; Verify ignition spark condition; Inspect spark plug cables, kill lead terminal at magneto and measure magneto air gap: replace terminals, set gap or replace magnetos as necessary; Dealers contact Distributor for technical support, Distributors contact factory for technical support
23Oil pressure switch faultWire connections, faulty switch
29High battery voltageIncorrect battery configuration, wire damage, faulty charger, controlVerify that Last Fault is FC 29: Yes, continue diagnosis; No, troubleshoot actual last fault; Measure DC voltage at battery, genset and connector P1: reconnect battery or repair wiring as necessary; Measure DC voltage with battery charger on: reduce boost charge rate or diagnose faulty charger as necessary; If genset shares batteries with propulsion engine, check for fault using shop battery (voltage spike may cause fault): diagnose fault or voltage spikes from propulsion engine charging system; Disconnect genset control P1 connector, verify P1 pins are fully inserted and inspect pin condition per PSB–676: insert, repair or replace pins as necessary; Reconnect P1 connector and test run genset for fault occurrence: replace controller
31Overspeed fault (HGJAD, E, F models only)Engine governor function, fuel supply, air fuel mixture, exhaust system, choke, demand regulator, carburetor, generator drive system, ignition, wire connectionsVerify that Last Fault is FC 31: Yes, continue diagnosis; No, troubleshoot actual last fault; Measure genset frequency and droop while running; Measure AC frequency while changing engine rpm to determine if frequency response matches engine rpm response: repair damaged generator drive system as necessary; Disconnect genset control P1 connector, verify P1 pins are fully inserted and inspect pin condition per PSB–676: insert, repair or replace pins as necessary; Inspect spark plug lead, kill lead terminal at magneto and measure magneto air gap: replace terminals, set gap or replace magnetos as necessary; Measure temperature of air intake and temperature rise across genset; remove blockage or prevent air recirculation; Dealers contact Distributor for technical support, Distributors contact factory for technical support
33Fault Code 33Fault Code 3 interpreted as a non-assigned Fault Code 33Verify that Last Fault is FC 3 Yes, continue diagnosis; No, troubleshoot actual last fault; While LED is flashing three times press stop once (1 second duration): trouble shoot Two-Digit Fault Code
35Control card failureFaulty programVerify that Last Fault is FC 35: Yes, continue diagnosis; No, troubleshoot actual last fault; Replace control
36Genset stopped without fault conditionAuto Gen Start (AGS), fuel supply, air fuel mixture, exhaust system, loads, Inverter/Charger, choke, demand regulator, carburetor, generator drive system, generator windings, ignition, wire connectionsVerify that Last Fault is FC 36: Yes, continue diagnosis; No, troubleshoot actual last fault; Verify whether AGS stopped genset: Yes, disable AGS or explain AGS function to customer (see PSB-666); No, continue diagnosis; Verify engine rotation manually: repair engine damage as necessary; Disconnect genset control P1 connector, verify P1 pins are fully inserted and inspect pin condition per PSB–676: insert, repair or replace pins as necessary; Reconnect P1 connector and test run genset for fault occurrence: repair or replace pins in connector as necessary; Check air filter cleanliness; replace air filter as necessary; Check for blocked or damaged exhaust system: repair or replace exhaust components as necessary; Measure AC current while running genset with vehicle loads: identify faulty or short cycling loads; Determine battery charge rate (typical default is 80 percent): if adjustable reduce to 30 percent; Measure genset load capability with shop load bank; HGJAD only – Run genset in Engine Run Only and externally excite field F1–F2 with 12 VDC or 24 VDC and measure main and quadrature winding AC output; Non EFI – Verify genset operation and outputs with Break-Out Tool 420–0603 and Instruction Sheet R1098; Measure AC frequency while changing engine rpm to determine if frequency response matches engine rpm response: repair damaged generator drive system as necessary; All Gasoline Models: Vapor lock may occur in high ambient temperatures: operate in ambients at less than 120°F; verify proper installation to prevent air recirculation; correct as necessary; Inspect throttle body for binding or damage: replace as necessary. Measure fuel pump pressure/flow: replace fuel filter, pressure regulator or fuel pump as necessary; Propane Models: When ambient temperatures are less than 40°F vapor-withdrawal Propane tanks should be at least half full to provide proper vaporization rate. Propane having more than 2.5 percent Butane will not vaporize in ambients at less than 32°F; use HD–5 grade Propane. Measure steady DC voltage at fuel solenoid while genset is running; repair wiring as necessary. Verify clear vent hose. Run genset on shop fuel supply; verify tank level and fuel line condition in vehicle. Check genset fuel lines for damage: replace fuel line as required. Measure regulator lock off pressure; Check governor, actuator, linkage and spring for debris, damage and looseness: readjust and repair as necessary; HGJAD only – Run genset in Engine Run Only and externally excite field F1–F2 with 12 VDC or 24 VDC and measure main and quadrature winding AC output; Non EFI – If the genset will not stay running measure genset frequency, quadrature winding and main winding voltages using Break-Out Tool 420–0603 and Instruction Sheet R1098; Remove connector P1 from control and re-install and try to start genset: inspect, repair or replace P1 connector pins as necessary; Measure field, quadrature and main winding resistance: clean slip rings, replace brushes, repair harness and replace rotor or stator as necessary; Measure field, quadrature and main winding resistance to ground: clean slip rings, replace brushes, repair harness and replace rotor or stator as necessary; Measure field, quadrature and main winding resistance to each other: clean slip rings, replace brushes, repair harness and replace rotor or stator as necessary; Check brush alignment per PSB-682a; Measure temperature of air intake and temperature rise across genset; remove blockage or prevent air recirculation; Dealers contact Distributor for technical support, Distributors contact factory for technical support
42Processor faultFaulty programVerify that Last Fault is FC 42: Yes, continue diagnosis; No, troubleshoot actual last fault; Replace control
43Processor faultFaulty programVerify that Last Fault is FC 43: Yes, continue diagnosis; No, troubleshoot actual last fault; Replace control
45Speed sense faultAuto Gen Start (AGS), fuel supply, air fuel mixture, exhaust system, loads, Inverter/Charger, choke, demand regulator, carburetor, generator drive system, generator windings, ignition, wire connectionsVerify that Last Fault is FC 45: Yes, continue diagnosis; No, troubleshoot actual last fault; Inspect spark plug lead, kill lead terminal at magneto and measure magneto air gap: replace terminals, set gap or replace magnetos as necessary; Measure temperature of air intake and temperature rise across genset; remove blockage or prevent air recirculation; Dealers contact Distributor for technical support, Distributors contact factory for technical support
47Ignition faultWire connections, windings, ignition system, generator drive systemVerify that Last Fault is FC 47: Yes, continue diagnosis; No, troubleshoot actual last fault; Alternating FC 47 and FC 37: Magneto gap too wide: reset magneto gap, retest; Test Magnetos: Disconnect Connector P1. Connect positive(+) meter lead to chassis ground. HGJAA, D, E, F – Measure continuity to negative lead at pin P1–4 and P1–5: replace magnetos as necessary. HGJAB, C – Measure continuity to negative lead at pin P1–15 and P1–20: replace magnetos as necessary; HGJAD only – Run genset in Engine Run Only and externally excite field with 12 VDC or 24 VDC and measure main and quadrature winding AC output; Non EFI only – If the genset will not stay running measure genset frequency, quadrature winding and main winding voltages using Break-Out Tool 420–0603 and Instruction Sheet R1098; Measure AC frequency while changing engine rpm to determine if frequency response matches engine rpm response: repair damaged generator drive system as necessary; Measure field, quadrature and main winding resistance: clean slip rings, replace brushes, repair harness and replace rotor or stator as necessary; Measure field, quadrature and main winding resistance to ground: clean slip rings, replace brushes, repair harness and replace rotor or stator as necessary; Measure field, quadrature and main winding resistance to each other: clean slip rings, replace brushes, repair harness and replace rotor or stator as necessary; Check brush alignment per PSB-682a; Verify that spark plug cables are secure on spark plugs: reconnect or replace as necessary; Inspect ignition kill leads in harness and at connector P1: repair or replace lead, terminal or pins as necessary; Measure spark plug gap: set gap or replace spark plugs as necessary; Verify ignition spark condition; Inspect spark plug lead, kill lead terminal at magneto and measure magneto air gap: replace terminals, set gap or replace magnetos as necessary; Dealers contact Distributor for technical support, Distributors contact factory for technical support
48Field Sense Fault — Controller unable to sense field voltageFaulty controlVerify that Last Fault is FC 48: Yes, continue diagnosis; No, troubleshoot actual last fault; Replace control.
51Processor Failure — Processor errorFaulty controlVerify that Last Fault is FC 51: Yes, continue diagnosis; No, troubleshoot actual last fault; Replace control.
52Fuel Injector Fault — Open or shorted fuel injectorP1–17, wire connections, fuel injectorVerify that Last Fault is FC 52: Yes, continue diagnosis; No, troubleshoot actual last fault; Measure P1–17 open to ground on EFI set: ground lead as required for carburetor configuration; Inspect connector at injectors for looseness and damage, repair or replace connector as necessary; Disconnect genset control P1 connector, verify P1 pins are fully inserted and inspect pin condition per PSB–676: insert, repair or replace pins as necessary; Reconnect P1 connector and test run genset for fault occurrence: repair or replace pins in connector as necessary; Measure for continuity between P1–23 – INJ1 and P1–35 – INJ2: repair or replace harness as necessary; Measure for continuity to ground from P1–23, P1–35, INJ1 and INJ2: repair or replace harness as necessary; Replace injector; Dealers contact Distributor for technical support, Distributors contact factory for technical support.
54MAT Sensor Fault — MAT sender input greater than 300K ohmsP1–17, wire connections, MAT senderVerify that Last Fault is FC 54: Yes, continue diagnosis; No, troubleshoot actual last fault; Measure P1–17 open to ground on EFI set: ground lead as required for carburetor configuration; Inspect connector at sender for looseness and damage, repair or replace connector as necessary; Disconnect genset control P1 connector, verify P1 pins are fully inserted and inspect pin condition per PSB–676: insert, repair or replace pins as necessary; Reconnect P1 connector and test run genset for fault occurrence: repair or replace pins in connector as necessary; Measure for continuity across harness between P1–25 – MAT(A) and P1–20 – MAT(B): repair or replace harness as necessary; Measure resistance of MAT: Replace sender as necessary; Dealers contact Distributor for technical support, Distributors contact factory for technical support.
56MAP Sensor Fault — MAP sensor input less than 50kPa at startP1–17, ambient pressure/altitude, wire connections, MAP sender, wide open throttle (WOT) during startVerify that Last Fault is FC 56: Yes, continue diagnosis; No, troubleshoot actual last fault; Measure P1–17 open to ground on EFI set: ground lead as required for carburetor configuration; Verify ambient pressure greater than 50kPa: change altitude; Inspect connector at sender for looseness and damage: repair or replace connector as necessary; Disconnect genset control P1 connector, verify P1 pins are fully inserted and inspect pin condition per PSB–676: insert, repair or replace pins as necessary; Reconnect P1 connector
12Overvoltage
15Underfrequency
27Voltage Sense Lost
32Low Cranking Speed Sense
37Invalid Set Configuration
38Field Overload (Overvoltage)
41Generator Rotor Fault
57Overprime Fault
2Low oil pressure shutdown — First-level shutdown code—Low oil pressure cutoff switch did not openLow oil pressure cutoff switch did not openCheck engine oil level and add oil as necessary (Page 17); Drain excess oil (above dipstick Full mark.)
3Service check shutdown — First-level shutdown code—Indicates fault with second-level shutdown codeIndicates fault with second-level shutdown codeCheck the second-level shutdown code by pressing STOP once. The second-level shutdown code will have two-digits. The faults are listed in numerical order in this table.
4Overcrank shutdown — First-level shutdown code—Cranking exceeded 30 seconds without engine startingCranking exceeded 30 seconds without engine startingGasoline Models – Check and fill the fuel tank, as necessary. (Note: The genset fuel pickup tube is probably higher up in the fuel tank than the vehicle engine pickup.); Prime the engine fuel system by holding the control switch at Stop/Prime for 30 seconds; Low Pressure LPG Models – Check and fill the LPG container, as necessary. On cold days the LPG container may have to be kept at least half full to provide the rate of vaporization necessary to keep up with the genset fuel demand; Open any closed fuel valves; Secure the spark plug leads on the spark plugs (Page 20); Replace the spark plugs (Page 20); Service the air cleaner (Page 19).
12Overvoltage shutdown — Controller unable to maintain rated voltageController unable to maintain rated voltageSee an authorized Onan dealer.
13Undervoltage shutdown — Controller unable to maintain rated voltageController unable to maintain rated voltageReduce the number of connected appliances, especially when air conditioners and battery chargers are running.
14Overfrequency shutdown — Engine governor unable to maintain rated frequencyEngine governor unable to maintain rated frequencySee an authorized Onan dealer.
15Underfrequency shutdown — Engine governor unable to maintain rated frequencyEngine governor unable to maintain rated frequencyReduce the number of connected appliances, especially when air conditioners and battery chargers are running.
19Governor actuator shutdown — Controller sensed open or shorted circuitController sensed open or shorted circuitSee an authorized Onan dealer.
22Governor actuator overload shutdown — Duration of operation at or near full-duty cycle beyond design limitDuration of operation at or near full-duty cycle beyond design limitReduce the number of connected appliances, especially when air conditioners and battery chargers are running; Service the air cleaner (Page 19); Check for and repair a blocked exhaust system.
23Low oil pressure cutoff switch shutdown — Controller sensed switch still open during start—not a running faultController sensed switch still open during start—not a running faultSee an authorized Onan dealer.
27Voltage sense shutdown — Controller unable to sense output voltageController unable to sense output voltageSee an authorized Onan dealer.
29High battery voltage shutdown — Voltage across battery system greater than 19 voltsVoltage across battery system greater than 19 voltsCheck battery bank connections and reconnect if necessary so that the 12 volt batteries serving the genset are connected in parallel (12 volt) rather than in series (24 volt); Select a lower battery boost charge rate.
31Overspeed shutdown — Engine speed greater than 3400 rpmEngine speed greater than 3400 rpmSee an authorized Onan dealer.
32Low cranking speed shutdown — Cranking speed less than 180 rpm for more than 2 secondsCranking speed less than 180 rpm for more than 2 secondsClean and tighten the positive (+) and negative (–) battery cable connections at the battery and at the genset; Recharge or replace the battery. Refer to the battery manufacturer's recommendations; Replace engine oil with oil of proper viscosity for ambient temperatures (Page 6). (High oil viscosity can slow down cranking speed.)
35Control card failure shutdown — Microprocessor EEPROM error during self-testMicroprocessor EEPROM error during self-testSee an authorized Onan dealer.
36Engine stopped shutdown — Engine stopped without command by controllerEngine stopped without command by controllerGasoline Models – Check and fill the fuel tank, as necessary. (Note: The genset fuel pickup tube is probably higher up in the fuel tank than the vehicle engine pickup.); Low Pressure LPG Models – Check and fill the LPG container, as necessary. On cold days the LPG container may have to be kept at least half full to provide the rate of vaporization necessary to keep up with the genset fuel demand; Secure the spark plug leads on the spark plugs (Page 20); Replace the spark plugs (Page 20); Service the air cleaner (Page 19); Check for mechanical damage.
37Invalid genset configuration shutdown — Wrong frequency/rpm ratioWrong frequency/rpm ratioSee an authorized Onan dealer.
38Overcurrent (field overload) shutdown — Low power factor loadsLow power factor loadsReduce the number of appliances running at the same time, especially those with high motor starting loads such as air conditioners; Have air conditioners and other appliances checked for proper operation. (A locked compressor rotor can cause very low power factor.)
41Generator rotor shutdown — Controller unable to sense field or output voltageController unable to sense field or output voltageSee an authorized Onan dealer.
42Processor shutdown — Microprocessor ROM error during self-testMicroprocessor ROM error during self-testSee an authorized Onan dealer.
43Processor shutdown — Microprocessor RAM error during self-testMicroprocessor RAM error during self-testSee an authorized Onan dealer.
45Speed sense shutdown — Controller unable to sense quadrature frequencyController unable to sense quadrature frequencySee an authorized Onan dealer.
47Ignition shutdown — Controller unable to sense ignitionController unable to sense ignitionSee an authorized Onan dealer.
48Generator field sense shutdown — Controller unable to sense field voltageController unable to sense field voltageSee an authorized Onan dealer.
51Processor shutdown — Microprocessor malfunctionMicroprocessor malfunctionSee an authorized Onan dealer.
52Fuel injector shutdown — Open or short circuit in fuel injectorOpen or short circuit in fuel injectorSee an authorized Onan dealer.
54MAT sender shutdown — Open or short circuit in MAT senderOpen or short circuit in MAT senderSee an authorized Onan dealer.
56MAP sender shutdown — Open or short circuit in MAP senderOpen or short circuit in MAP senderSee an authorized Onan dealer.
57Overprime shutdown — Prime mode exceeded 3 minutesPrime mode exceeded 3 minutesCheck for and remove any object that may be holding either control switch (remote or local) in the prime position.
CODE NO. 12OVERVOLTAGE SHUTDOWN—Controller unable to maintain rated voltageCorrective Action: See an authorized Onan dealer.
CODE NO. 13UNDERVOLTAGE SHUTDOWN—Controller unable to maintain rated voltageCorrective Action: Reduce the number of connected appliances, especially when air conditioners and battery chargers are running.
CODE NO. 14OVERFREQUENCY SHUTDOWN—Engine governor unable to maintain rated frequencyCorrective Action: See an authorized Onan dealer.
CODE NO. 15UNDERFREQUENCY SHUTDOWN—Engine governor unable to maintain rated frequencyCorrective Action: Reduce the number of connected appliances, especially when air conditioners and battery chargers are running.
CODE NO. 19GOVERNOR ACTUATOR SHUTDOWN—Controller sensed open or shorted circuitCorrective Action: See an authorized Onan dealer.
CODE NO. 22GOVERNOR ACTUATOR OVERLOAD SHUTDOWN—Duration of operation at or near full-duty cycle beyond design limit1. Reduce the number of connected appliances, especially when air conditioners and battery chargers are running. 2. Service the air cleaner (Page 19). 3. Check for and repair a blocked exhaust system.
CODE NO. 23LOW OIL PRESSURE CUTOFF SWITCH SHUTDOWN—Controller sensed switch still open during start—not a running faultCorrective Action: See an authorized Onan dealer.
CODE NO. 27VOLTAGE SENSE SHUTDOWN—Controller unable to sense output voltageCorrective Action: See an authorized Onan dealer.
CODE NO. 29HIGH BATTERY VOLTAGE SHUTDOWN—Voltage across battery system greater than 19 volts1. Check battery bank connections and reconnect if necessary so that the 12 volt batteries serving the genset are connected in parallel (12 volt) rather than in series (24 volt). 2. Select a lower battery boost charge rate.
CODE NO. 31OVERSPEED SHUTDOWN—Engine speed greater than 3400 rpmCorrective Action: See an authorized Onan dealer.
CODE NO. 32LOW CRANKING SPEED SHUTDOWN—Cranking speed less than 180 rpm for more than 2 seconds1. Clean and tighten the positive (+) and negative (–) battery cable connections at the battery and at the genset. 2. Recharge or replace the battery. Refer to the battery manufacturer’s recommendations. 3. Replace engine oil with oil of proper viscosity for ambient temperatures (Page 6). (High oil viscosity can slow down cranking speed.)
CODE NO. 35CONTROL CARD FAILURE SHUTDOWN—Microprocessor EEPROM error during self-testCorrective Action: See an authorized Onan dealer.
CODE NO. 36ENGINE STOPPED SHUTDOWN—Engine stopped without command by controller1. Gasoline Models – Check and fill the fuel tank, as necessary. 2. Low Pressure LPG Models – Check and fill the LPG container, as necessary. On cold days the LPG container may have to be kept at least half full to provide the rate of vaporization necessary to keep up with the genset fuel demand. 3. Secure the spark plug leads on the spark plugs (Page 20). 4. Replace the spark plugs (Page 20). 5. Service the air cleaner (Page 19).= 6. Check for mechanical damage.
CODE NO. 37INVALID GENSET CONFIGURATION SHUTDOWN—Wrong frequency/rpm ratioCorrective Action: See an authorized Onan dealer.
CODE NO. 38OVERCURRENT (FIELD OVERLOAD) SHUTDOWN—Low power factor loads1. Reduce the number of appliances running at the same time, especially those with high motor starting loads such as air conditioners. 2. Have air conditioners and other appliances checked for proper operation. (A locked compressor rotor can cause very low power factor.)
CODE NO. 41GENERATOR ROTOR SHUTDOWN—Controller unable to sense field or output voltageCorrective Action: See an authorized Onan dealer.
CODE NO. 42PROCESSOR SHUTDOWN—Microprocessor ROM error during self-testCorrective Action: See an authorized Onan dealer.
CODE NO. 43PROCESSOR SHUTDOWN—Microprocessor RAM error during self-testCorrective Action: See an authorized Onan dealer.
CODE NO. 45SPEED SENSE SHUTDOWN—Controller unable to sense quadrature frequencyCorrective Action: See an authorized Onan dealer.
CODE NO. 47IGNITION SHUTDOWN—Controller unable to sense ignitionCorrective Action: See an authorized Onan dealer.
CODE NO. 48GENERATOR FIELD SENSE SHUTDOWN—Controller unable to sense field voltageCorrective Action: See an authorized Onan dealer.
CODE NO. 51PROCESSOR SHUTDOWN—Microprocessor malfunctionCorrective Action: See an authorized Onan dealer.
CODE NO. 52FUEL INJECTOR SHUTDOWN—Open or short circuit in fuel injectorCorrective Action: See an authorized Onan dealer.
2Low Oil Pressure FaultLow/high oil level; faulty switch; faulty oil pressure relief valve; fault oil pumpVerify that Last Fault is FC 2: Yes, continue diagnosis; No, troubleshoot actual last fault; Measure oil level: add or drain oil as necessary; Disconnect genset control P1 connector, verify P1 pins are fully inserted and inspect pin condition per PSB-676: insert, repair or replace pins as necessary; Reconnect P1 connector and test run genset for fault occurrence: repair or replace pins in connector as necessary; Measure continuity change across start/stop switch between rest and under simulated pressure: replace switch as necessary; HGJAB, C — Measure continuity between ground and P1-13: repair or replace harness as necessary. HGJAA, D, E, F — Measure continuity between ground and P1-6: repair or replace harness as necessary; Measure oil pressure with mechanical gauge: repair or replace relief valve and oil pump as necessary
3Service Check Fault — Single-Digit Fault to indicate shutdown due to a Two-Digit FaultAny Two-Digit Fault CodeVerify that Last Fault is FC 3: Yes, continue diagnosis; No, troubleshoot actual last fault; While LED is flashing three times press stop once (1 second duration): trouble shoot Two-Digit Fault Code
4Overcrank — Controller unable to sense genset frequency after 30 seconds of holding start switchFaulty switch; faulty external start command; fuel supply; air fuel mixture; exhaust system; wire connections; starter; ignition system
12Overvoltage — Instantaneous Fault − AC voltage S1−S2 greater than 150 VAC; Delayed Fault − AC voltage S1−S2 greater than 138 VAC, but less than 150 VAC for 3 continuous minutesGenset loads; Inverter/Charger; wire connections; AC sense transformer; windingsVerify that Last Fault is FC 12: Yes, continue diagnosis; No, troubleshoot actual last fault; Measure AC voltage; Measure AC frequency while changing engine rpm to determine if frequency response matches engine rpm response: repair damaged generator drive system as necessary; Cycle loads to determine if a particular load causes fault: diagnose faulty load as necessary; Determine Inverter/Charger battery charge rate (typical default is 80 percent): if adjustable reduce to 30 percent; Verify balanced loads in 120/240 VAC applications: balance loads within 10 percent line−to−line as required; HGJAD only − Run genset in Engine Run Only mode and externally excite field F1−F2 with 12 VDC or 24 VDC and measure main and quadrature winding AC output; Non EFI − If the genset will not stay running measure genset frequency, quadrature winding and main winding voltages using Break-Out Tool 420−0603 and Instruction Sheet R1098; Remove connector P1 from control and re-install and try to start genset: inspect, repair or replace P1 connector pins as necessary; Measure field, quadrature and main winding resistance: clean slip rings, replace brushes, repair harness and replace rotor or stator as necessary; Measure field, quadrature and main winding resistance to ground: clean slip rings, replace brushes, repair harness and replace rotor or stator as necessary; Measure field, quadrature and main winding resistance to each other: clean slip rings, replace brushes, repair harness and replace rotor or stator as necessary; Check brush alignment per PSB-682a; Dealers contact Distributor for technical support, Distributors contact factory for technical support
13Undervoltage — AC voltage S1−S2 less than 108 VAC for 5 continuous secondsGenset loads; Inverter/Charger; wire connections; generator drive system; windings; AC sense transformer; windingsVerify that Last Fault is FC 13: Yes, continue diagnosis; No, troubleshoot actual last fault; Measure AC voltage; Measure AC voltage in and out of sense transformer (if so equipped): repair wire connection, replace sense transformer as necessary; Measure AC frequency while changing engine rpm to determine if frequency response matches engine rpm response: repair damaged generator drive system as necessary; Cycle loads to determine if a particular load will cause fault: diagnose faulty load as necessary; Determine battery charge rate (typical default is 80 percent): if adjustable reduce to 30 percent; Verify balanced loads in 120/240 VAC applications: balance loads within 10 percent line−to−line as required; HGJAD only − Run genset in Engine Run Only mode and externally excite field F1−F2 with 12 VDC or 24 VDC and measure main and quadrature winding AC output; Non EFI − If the genset will not stay running measure genset frequency
17Fuel Pump Fault — Only Active Prior to 2001 − Open fuel pump circuit at controlWire connections; harness leads; faulty fuel pumpVerify that Last Fault is FC 17: Yes, continue diagnosis; No, troubleshoot actual last fault; Verify fuel pump operation in prime mode, if pump operates fault condition has been cleared verify harness connections, no further troubleshooting; HGJAA, D Check continuity across fuse F1; Disconnect genset control P1 connector, verify P1 pins are fully inserted and inspect pin condition per PSB−676: insert, repair or replace pins as necessary; Reconnect P1 connector, prime genset to verify pump operation and test run genset for fault occurrence; Measure continuity between E2 fuel pump leads; replace terminals or fuel pump as necessary; Measure voltage between fuel pump E2 + and ground while priming; replace terminals, harness leads or control as necessary
19Governor Actuator (EFI Only) — Shorted or open connection between governor leads after pressing startWire connections; P1−17; governor actuator (Does Not Pertain to Model HGJAA)Verify that Last Fault is FC 19: Yes, continue diagnosis; No, troubleshoot actual last fault; Disconnect genset control P1 connector, verify P1 pins are fully inserted and inspect pin condition per PSB−676: insert, repair or replace pins as necessary; Reconnect P1 connector and test run genset for fault occurrence: repair or replace pins in connector as necessary; P1−17 open to ground on EFI Models: ground lead as required for carburetor configuration; Verify actuator function by applying DC voltage to terminals: replace actuator as necessary; Measure resistance between actuator terminals; repair or replace connections as necessary, replace governor actuator; Measure continuity between P1−28 and actuator lead; repair or replace terminals and leads as necessary; Measure DC voltage at actuator while starting: replace controller as necessary
22Governor Actuator Overload (EFI Only) — Only active Prior to 2001 − Maximum governor output (PWM) for 10 continuous secondsGenset loads; Inverter/Charger; wire connections; fuel supply; air fuel mixture; exhaust system; governor actuator; ignition systemVerify that Last Fault is FC 22: Yes, continue diagnosis; No, troubleshoot actual last fault; Measure AC current while running genset with vehicle loads: identify faulty or short cycling loads or reduce vehicle loads as necessary; Determine battery charge rate (typical default is 80 percent): if adjustable reduce to 30 percent; Measure genset load capability with shop load bank (derate for altitude and temperature as necessary); Measure AC frequency and droop while running; Measure AC frequency while changing engine rpm to determine if frequency response matches engine rpm response: repair damaged generator drive system as necessary; Disconnect genset control P1 connector, verify P1 pins are fully inserted and inspect pin condition per PSB−676: insert, repair or replace pins as necessary; Reconnect P1 connector and test run genset for fault occurrence: repair or replace pins in connector as necessary; Check air filter cleanliness; replace air filter as necessary; Check intake manifold and gaskets for air leaks: tighten fasteners and replace gaskets and manifold as necessary; Check for blocked or damaged exhaust system: repair or replace exhaust components as necessary; Measure fuel pump pressure/flow: replace fuel filter, pressure regulator or fuel pump as necessary; Verify actuator function by applying DC voltage to terminals: replace actuator as necessary; Check throttle body for binding; inspect spring for dirt and debris: clean spring, replace throttle body as necessary; Verify that spark plug cables are secure on spark plugs: reconnect or replace as necessary; Inspect ignition kill leads in harness and at connector P1: repair or replace lead, terminal or pins as necessary; Test Magnetos: Disconnect Connector P1; Connect positive(+) meter lead to chassis ground; HGJAA, D, E, F − Measure continuity to negative lead at pin P1−4 and P1−5: replace magnetos as necessary; HGJAB, C − Measure continuity to negative lead at pin P1−15 and P1−20: replace magnetos as necessary; Measure spark plug gap: set gap or replace spark plugs as necessary; Verify ignition spark condition; Inspect spark plug cables, kill lead terminal at magneto and measure magneto air gap: replace terminals, set gap or replace magnetos as necessary; Dealers contact Distributor for technical support, Distributors contact factory for technical support
23Oil Pressure Switch Fault — Only Active Prior to 2001 − Continuous open on oil pressure switch input before crankingWire connections; faulty switchVerify that Last Fault is FC 23: Yes, continue diagnosis; No, troubleshoot actual last fault; Verify harness lead is connected to switch: repair or replace terminal as necessary; Disconnect genset control P1 connector, verify P1 pins are fully inserted and inspect pin condition per: insert, repair or replace pins as necessary; Reconnect P1 connector and test run genset for fault occurrence; Measure continuity to ground at switch and through harness at P1 connector: replace switch, repair or replace harness as necessary
27Voltage Sense Lost — No Sense Voltage (0 VAC across S1−S2) for 1 continuous second after start disconnectGenset loads; Inverter/Charger; VAC sense transformer; engine governor function; fuel supply; choke; demand regulator; carburetor; generator windings; ignition; wire connections; temperatureVerify that Last Fault is FC 27: Yes, continue diagnosis; No, troubleshoot actual last fault; Measure AC voltage; Determine battery charge rate (typical default is 80 percent): if adjustable reduce to 30 percent; Disconnect genset control P1 connector, verify P1 pins are fully inserted and inspect pin condition per PSB−676: insert, repair or replace pins as necessary; Reconnect P1 connector and test run genset for fault occurrence: repair or replace pins in connector as necessary; Check air filter cleanliness; replace air filter as necessary; Check for blocked or damaged exhaust system: repair or replace exhaust components as necessary; HGJAD only − Run genset in Engine Run Only and externally excite field with 12 VDC or 24 VDC and measure main and quadrature winding AC output; Non EFI only
33Fault Code 33 — Single-Digit Fault to indicate shutdown due to Two-Digit Fault CodeFault Code 3 interpreted as a non-assigned Fault Code 33Verify that Last Fault is FC 3 Yes, continue diagnosis; No, troubleshoot actual last fault; While LED is flashing three times press stop once (1 second duration): trouble shoot Two-Digit Fault Code
35Control Card Failure — EEPROM (programming variables) error during self testFaulty programVerify that Last Fault is FC 35: Yes, continue diagnosis; No, troubleshoot actual last fault; Replace control
36Genset Stopped Without Fault Condition — RPM less than 500 and Sense Voltage S1−S2 at 0 VAC when no other fault condition occurredAuto Gen Start (AGS); fuel supply; air fuel mixture; exhaust system; loads; Inverter/Charger; choke; demand regulator; carburetor; generator drive system; generator windings; ignition; wire connectionsVerify that Last Fault is FC 36: Yes, continue diagnosis; No, troubleshoot actual last fault; Verify whether AGS stopped genset: Yes, disable AGS or explain AGS function to customer (see PSB-666); No, continue diagnosis; Verify engine rotation manually: repair engine damage as necessary; Disconnect genset control P1 connector
37Configuration Fault — Configuration is determined by ratio of quadrature frequency / ignition speedWire connections; windings; ignition system; drive belt slippage; generator drive systemVerify that Last Fault is FC 37: Yes, continue diagnosis; No, troubleshoot actual last fault; Alternating FC 37 and FC 47: Magneto gap to wide: reset magneto gap, retest; HGJAD only − Run genset in Engine Run Only and externally excite field with 12 VDC or 24 VDC and measure main and quadrature winding AC output; Non EFI only − If the genset will not stay running measure genset frequency, quadrature winding and main winding voltages using Break-Out Tool 420−0603 and Instruction Sheet R1098; Measure AC frequency while changing engine rpm to determine if frequency response matches engine rpm response: repair damaged generator drive system as necessary; Measure field, quadrature and main winding resistance: clean slip rings, replace brushes, repair harness and replace rotor or stator as necessary; Measure field, quadrature and main winding resistance to ground: clean slip rings, replace brushes, repair harness and replace rotor or stator as necessary; Measure field, quadrature and main winding resistance to each other: clean slip rings, replace brushes, repair harness and replace rotor or stator as necessary; Check brush alignment per PSB-682a; Verify that spark plug cables are secure on spark plugs: reconnect or replace as necessary; Inspect ignition kill leads in harness and at connector P1: repair or replace lead, terminal or pins as necessary; Test Magnetos: Disconnect Connector P1; Connect positive(+) meter lead to chassis ground; HGJAA, D, E, F − Measure continuity to negative lead at pin P1−4 and P1−5: replace magnetos as necessary; HGJAB, C − Measure continuity to negative lead at pin P1−15 and P1−20: replace magnetos as necessary; Measure spark plug gap: set gap or replace spark plugs as necessary; Verify ignition spark condition; Inspect spark plug lead, kill lead terminal at magneto and measure magneto air gap: replace terminals, set gap or replace magnetos as necessary; Dealers contact Distributor for technical support, Distributors contact factory for technical support
38Field Overload (Overvoltage) — Field voltage (F1−F1) greater than 150 VDC for 10 continuous secondsLoads; Inverter/Charger; windings; fuel supply; governor systemVerify that Last Fault is FC 38: Yes, continue diagnosis; No, troubleshoot actual last fault; Measure F1−F2 DC voltage; Measure AC current while running genset with vehicle loads: identify faulty or short cycling loads; Determine battery charge rate (typical default is 80 percent): if adjustable reduce to 30 percent; Disconnect genset control P1 connector, verify P1 pins are fully inserted and inspect pin condition per PSB−676: insert, repair or replace pins as necessary; Reconnect P1 connector and test run genset for fault occurrence: repair or replace pins in connector as necessary; Measure genset load capability with shop load bank (derate for altitude and temperature as necessary); Measure genset frequency and droop while running; Check governor, actuator, linkage and spring for debris, damage and looseness: readjust and repair as necessary; Check air filter cleanliness; replace air filter as necessary; Check for blocked or damaged exhaust system: repair or replace exhaust components as necessary; All Gasoline Models
42Processor Fault — ROM (programming variables) error during self testFaulty programVerify that Last Fault is FC 42: Yes, continue diagnosis; No, troubleshoot actual last fault; Replace control
43Processor Fault — RAM (programming variables) error during self testFaulty programVerify that Last Fault is FC 43: Yes, continue diagnosis; No, troubleshoot actual last fault; Replace control
45Speed Sense Fault — While running quadrature frequency dropped to 0Hz for 1 continuous secondAuto Gen Start (AGS); fuel supply; air fuel mixture; exhaust system; loads; Inverter/Charger; choke; demand regulator; carburetor; generator drive system; generator windings; ignition; wire connectionsVerify that Last Fault is FC 45: Yes, continue diagnosis; No, troubleshoot actual last fault; Verify whether AGS stopped genset: Yes, disable AGS or explain AGS function to customer (see PSB-666); No, continue diagnosis; Verify engine rotation manually: repair engine damage as necessary; Disconnect genset control P1 connector, verify P1 pins are fully inserted and inspect pin condition per PSB−676: insert, repair or replace pins as necessary; Reconnect P1 connector and test run genset for fault occurrence: repair or replace pins in connector as necessary; Check air filter cleanliness; replace air filter as necessary; Check for blocked or damaged exhaust system: repair or replace exhaust components as necessary; Measure AC current while running genset with vehicle loads: identify faulty or short cycling loads; Determine battery charge rate (typical default is 80 percent): if adjustable reduce to 30 percent; Measure genset load capability with shop load bank (derate for altitude and temperature as necessary); HGJAD only − Run genset in Engine Run Only and externally excite field F1−F2 with 12 VDC or 24 VDC and measure main and quadrature winding AC output; Non EFI − Verify genset operation and outputs with Break-Out Tool 420−0603 and Instruction Sheet R1098; Measure genset frequency and droop while running; Measure AC frequency while changing engine rpm to determine if frequency response matches engine rpm response: repair damaged generator drive system as necessary; All Gasoline Models; All Gasoline Carburetor Models; All Gasoline EFI Models; Propane Models; Check governor, actuator, linkage and spring for debris, damage and looseness: readjust and repair as necessary; Verify that spark plug cables are secure on spark plugs: reconnect or replace as necessary; Test Magnetos: Disconnect Connector P1; Connect positive(+) meter lead to chassis ground; HGJAA, D, E, F − Measure continuity to negative lead at pin P1−4 and P1−5: replace magnetos as necessary; HGJAB, C − Measure continuity to negative lead at pin P1−15 and P1−20: replace magnetos as necessary; Inspect ignition kill leads in harness and at connector P1: repair or replace lead, terminal or pins as necessary; Measure spark plug gap: set gap or replace spark plugs as necessary; Verify ignition spark condition; Inspect spark plug lead, kill lead terminal at magneto and measure magneto air gap: replace terminals, set gap or replace magnetos as necessary; Measure temperature of air intake and temperature rise across genset; remove blockage or prevent air recirculation; Dealers contact Distributor for technical support, Distributors contact factory for technical support
47Ignition Fault — HGJAB, C − No ignition signal at P1−15 for 1 continuous second; HGJAA − No ignition signal at P1−5 for 1 continuous second; HGJAD, E, F prior to 2004 − No ignition signal at P1−5 for 1 continuous second; HGJAD, E, F after 2004 in Engine Run Only mode only − No ignition signal at P1−5 for continuous secondWire connections; windings; ignition system; generator drive systemVerify that Last Fault is FC 47: Yes, continue diagnosis; No, troubleshoot actual last fault; Alternating FC 47 and FC 37: Magneto gap too wide: reset magneto gap, retest; Test Magnetos: Disconnect Connector P1; Connect positive(+) meter lead to chassis ground; HGJAA, D, E, F − Measure continuity to negative lead at pin P1−4 and P1−5: replace magnetos as necessary; HGJAB, C − Measure continuity to negative lead at pin P1−15 and P1−20: replace magnetos as necessary; HGJAD only − Run genset in Engine Run Only and externally excite field with 12 VDC or 24 VDC and measure main and quadrature winding AC output; Non EFI only − If the genset will not stay running measure genset frequency, quadrature winding and main winding voltages using Break-Out Tool 420−0603 and Instruction Sheet R1098; Measure AC frequency while changing engine rpm to determine if frequency response matches engine rpm response: repair damaged generator drive system as necessary; Measure field, quadrature and main winding resistance: clean slip rings, replace brushes, repair harness and replace rotor or stator as necessary; Measure field, quadrature and main winding resistance to ground: clean slip rings, replace brushes, repair harness and replace rotor or stator as necessary; Measure field, quadrature and main winding resistance to each other: clean slip rings, replace brushes, repair harness and replace rotor or stator as necessary; Check brush alignment per PSB-682a; Verify that spark plug cables are secure on spark plugs: reconnect or replace as necessary; Inspect ignition kill leads in harness and at connector P1: repair or replace lead, terminal or pins as necessary; Measure spark plug gap: set gap or replace spark plugs as necessary; Verify ignition spark condition; Inspect spark plug lead, kill lead terminal at magneto and measure magneto air gap: replace terminals, set gap or replace magnetos as necessary; Dealers contact Distributor for technical support, Distributors contact factory for technical support
52Fuel Injector Fault — Open or shorted fuel injectorP1−17; wire connections; fuel injector (Does not pertain to HGJAA Models)Verify that Last Fault is FC 52: Yes, continue diagnosis; No, troubleshoot actual last fault; Measure P1−17 open to ground on EFI set: ground lead as required for carburetor configuration; Inspect connector at injectors for looseness and damage, repair or replace connector as necessary; Disconnect genset control P1 connector, verify P1 pins are fully inserted and inspect pin condition per PSB−676: insert, repair or replace pins as necessary; Reconnect P1 connector and test run genset for fault occurrence: repair or replace pins in connector as necessary; Measure for continuity between P1−23 − INJ1 and P1−35 − INJ2: repair or replace harness as necessary; Measure for continuity to ground from P1−23, P1−35, INJ1 and INJ2: repair or replace harness as necessary; Replace injector; Dealers contact Distributor for technical support, Distributors contact factory for technical support
54MAT SENSOR FAULTMAT sender input greater than 300K ohms; P1−17; wire connections; MAT senderVerify that Last Fault is FC 54: Yes, continue diagnosis; No, troubleshoot actual last fault; Measure P1−17 open to ground on EFI set: ground lead as required for carburetor configuration; Inspect connector at sender for looseness and damage, repair or replace connector as necessary; Disconnect genset control P1 connector, verify P1 pins are fully inserted and inspect pin condition per PSB−676: insert, repair or replace pins as necessary; Reconnect P1 connector and test run genset for fault occurrence: repair or replace pins in connector as necessary; Measure for continuity across harness between P1−25 − MAT(A) and P1−20 − MAT(B): repair or replace harness as necessary; Measure resistance of MAT: Replace sender as necessary; Dealers contact Distributor for technical support, Distributors contact factory for technical support
56MAP SENSOR FAULTMAP sensor input less than 50kPa at start; P1−17; ambient pressure/altitude; wire connections; MAP sender; wide open throttle (WOT) during startVerify that Last Fault is FC 56: Yes, continue diagnosis; No, troubleshoot actual last fault
14Overfrequency
29High Battery Voltage
31Overspeed Fault (HGJAD, E, F Models Only)
No. 4The genset does not start after two or three tries.Wait 5 seconds for the control to reset before trying again.
1High engine coolant temperatures
2LOW OIL PRESSURE SHUTDOWNLow oil pressure cutoff switch did not openCheck engine oil level and add oil as necessary (Page Section 4.2); Drain excess oil (above dipstick Full mark.)
3SERVICE CHECK SHUTDOWNIndicates fault with second-level shutdown codeCheck the second-level shutdown code by pressing STOP once. The second-level shutdown code will have two-digits. The faults are listed in numerical order in this table.
4OVERCRANK SHUTDOWNCranking exceeded 30 seconds without engine startingGasoline Models -Check and fill the fuel tank, as necessary. (Note: The genset fuel pickup tube is probably higher up in the fuel tank than the vehicle engine pickup.); Prime the engine fuel system by holding the control switch at Stop/Prime for 30 seconds; Low Pressure LPG Models - Check and fill the LPG container, as necessary. On cold days the LPG container may have to be kept at least half full to provide the rate of vaporization necessary to keep up with the genset fuel demand; Open any closed fuel valves; Secure the spark plug leads on the spark plugs (Page Section 4.6); Replace the spark plugs (Page Section 4.6); Service the air cleaner (Page Section 4.5).
12OVERVOLTAGE SHUTDOWNController unable to maintain rated voltageSee an authorized Onan dealer.
13UNDERVOLTAGE SHUTDOWNController unable to maintain rated voltageReduce the number of connected appliances, especially when air conditioners and battery chargers are running.
14OVERFREQUENCY SHUTDOWNEngine governor unable to maintain rated frequencySee an authorized Onan dealer.
15UNDERFREQUENCY SHUTDOWNEngine governor unable to maintain rated frequencyReduce the number of connected appliances, especially when air conditioners and battery chargers are running.
19GOVERNOR ACTUATOR SHUTDOWNController sensed open or shorted circuitSee an authorized Onan dealer.
22GOVERNOR ACTUATOR OVERLOAD SHUTDOWNDuration of operation at or near full-duty cycle beyond design limitReduce the number of connected appliances, especially when air conditioners and battery chargers are running; Service the air cleaner (Page Section 4.5); Check for and repair a blocked exhaust system.
23LOW OIL PRESSURE CUTOFF SWITCH SHUTDOWNController sensed switch still open during start—not a running faultSee an authorized Onan dealer.
27VOLTAGE SENSE SHUTDOWNController unable to sense output voltageSee an authorized Onan dealer.
29HIGH BATTERY VOLTAGE SHUTDOWNVoltage across battery system greater than 19 voltsCheck battery bank connections and reconnect if necessary so that the 12 volt batteries serving the genset are connected in parallel (12 volt) rather than in series (24 volt); Select a lower battery boost charge rate.
31OVERSPEED SHUTDOWNEngine speed greater than 3400 rpmSee an authorized Onan dealer.
32LOW CRANKING SPEED SHUTDOWNCranking speed less than 180 rpm for more than 2 secondsClean and tighten the positive (+) and negative (-) battery cable connections at the battery and at the genset; Recharge or replace the battery. Refer to the battery manufacturer's recommendations; Replace engine oil with oil of proper viscosity for ambient temperatures (Page Section 2.5). (High oil viscosity can slow down cranking speed.)
35CONTROL CARD FAILURE SHUTDOWNMicroprocessor EEPROM error during self-testSee an authorized Onan dealer.
36ENGINE STOPPED SHUTDOWNEngine stopped without command by controllerGasoline Models -Check and fill the fuel tank, as necessary. (Note: The genset fuel pickup tube is probably higher up in the fuel tank than the vehicle engine pickup.); Low Pressure LPG Models - Check and fill the LPG container, as necessary. On cold days the LPG container may have to be kept at least half full to provide the rate of vaporization necessary to keep up with the genset fuel demand; Secure the spark plug leads on the spark plugs (Page Section 4.6); Replace the spark plugs (Page Section 4.6); Service the air cleaner (Page Section 4.5); Check for mechanical damage.
37INVALID GENSET CONFIGURATION SHUTDOWNWrong frequency/rpm ratioSee an authorized Onan dealer.
38OVERCURRENT (FIELD OVERLOAD) SHUTDOWNLow power factor loadsReduce the number of appliances running at the same time, especially those with high motor starting loads such as air conditioners; Have air conditioners and other appliances checked for proper operation. (A locked compressor rotor can cause very low power factor.)
41GENERATOR ROTOR SHUTDOWNController unable to sense field or output voltageSee an authorized Onan dealer.
42PROCESSOR SHUTDOWNMicroprocessor ROM error during self-testSee an authorized Onan dealer.
43PROCESSOR SHUTDOWNMicroprocessor RAM error during self-testSee an authorized Onan dealer.
45SPEED SENSE SHUTDOWNController unable to sense quadrature frequencySee an authorized Onan dealer.
47IGNITION SHUTDOWNController unable to sense ignitionSee an authorized Onan dealer.
48GENERATOR FIELD SENSE SHUTDOWNController unable to sense field voltageSee an authorized Onan dealer.
51PROCESSOR SHUTDOWNMicroprocessor malfunctionSee an authorized Onan dealer.
52FUEL INJECTOR SHUTDOWNOpen or short circuit in fuel injectorSee an authorized Onan dealer.
54MAT SENDER SHUTDOWNOpen or short circuit in MAT senderSee an authorized Onan dealer.
56MAP SENDER SHUTDOWNOpen or short circuit in MAP senderSee an authorized Onan dealer.
57OVERPRIME SHUTDOWNPrime mode exceeded 3 minutesCheck for and remove any object that may be holding either control switch (remote or local) in the prime position.
58Exhaust Gas Temp Shutdown/FaultExhaust gas temperatures reach 650C (1202F) for 2 secs when the set is runningSee an authorized Onan dealer
81OVERPRIME SHUTDOWNWhile running, EGT temp falls below 60C (140F) for 2 minutes - OR - if EGT temperature is not above 60C (140F) after 2 minutes from starting, set will shut downSee an authorized Onan dealer
82Exhaust Gas Temp Shutdown/FaultWith the set running and/or startup - control reads 1000C (1832F) for 1 secondSee an authorized Onan dealer
CODE NO. 52FUEL INJECTOR SHUTDOWN(Open or short circuit in fuel injector)See an authorized Onan dealer.
CODE NO. 54MAT SENDER SHUTDOWN(Open or short circuit in MAT sender)See an authorized Onan dealer.
CODE NO. 56MAP SENDER SHUTDOWN(Open or short circuit in MAP sender)See an authorized Onan dealer.
CODE NO. 57OVERPRIME SHUTDOWN(Prime mode exceeded 3 minutes)Check for and remove any object that may be holding either control switch (remote or local) in the prime position.
CODE NO. 58Exhaust Gas Temp Shutdown/Fault(Exhaust gas temperatures reach 650C (1202F) for 2 secs when the set is running)See an authorized Onan dealer

Symptoms & remedies

SymptomCauseRemedy
Genset Starts or Stops Without Command – No Fault CodeLow battery voltage, shorted harness connection, faulty start/stop switch, Auto Gen Start (AGS) is enabledCheck last fault and record; Measure battery voltage at battery and genset; Inspect battery connections and cables for cleanliness, tightness and damage: clean, tighten and repair connections and cables as necessary; Check electrolyte level and hydrometer reading in maintenance type batteries: replace electrolyte and recharge or replace battery as necessary; Disconnect genset control P1 connector, verify P1 pins are fully inserted and inspect pin condition per PSB–676: insert, repair or replace pins as necessary; Reconnect P1 connector and test run genset for symptom: repair or replace pins in connector as necessary; Measure battery voltage at genset while attempting to start from local or remote switch: recharge or replace battery if voltage drops below 9 VDC, test and service genset battery charger if so equipped, increase battery cable size or run parallel cables; Measure battery voltage and check for charger increase while genset is running; Measure for continuity change across start/stop switch between neutral and start position and neutral and stop position at switches and at connector P1: reconnect or repair connections, replace switches as necessary; Measure for continuity from start and stop inputs to ground at switches and at connector P1: Repair or replace damaged harness; Determine if AGS is installed and enabled (AGS will command start and stop based on its own settings): disable AGS or explain AGS function to customer (see PSB-666)
No Response – Status Indicator Light DeadLow/No battery voltage, poor battery connection, faulty battery, open harness connection, faulty start/stop switch, faulty LEDMeasure battery voltage at battery, at genset and at connector P1: reconnect, clean, repair and replace connections as necessary; Measure battery voltage at genset while attempting to start or prime from local or remote switch: recharge or replace battery if voltage drops below 9 VDC, test and service genset battery charger if so equipped, increase battery cable size or run parallel cables; Measure for continuity change across start/stop switch between neutral and start position and neutral and stop position at switches and at connector P1: reconnect or repair connections, replace switches as necessary; Test switches LED by energizing with 12 VDC: replace switches as necessary; Disconnect genset control P1 connector, verify P1 pins are fully inserted and inspect pin condition per PSB–676: insert, repair or replace pins as necessary; Reconnect P1 connector and test run genset for start and prime operation: replace control as necessary
Starting Batteries Run DownBattery connections, battery, charging system, excessive cranking, excessive primingMeasure battery voltage at battery and genset; Inspect battery connections and cables for cleanliness, tightness and damage: clean, tighten and repair connections and cables as necessary; Check electrolyte level and hydrometer reading in maintenance type batteries: replace electrolyte and recharge or replace battery as necessary; Verify battery charger is on and check operation; Measure battery voltage and check for charging increase while genset is running; Check last fault and record: troubleshoot as necessary; Disconnect genset control P1 connector, verify P1 pins are fully inserted and inspect pin condition per PSB–676: insert, repair or replace pins as necessary; Reconnect P1 connector and test run genset for fault occurrence: repair or replace pins in connector as necessary; Measure for continuity change across start/stop switch between neutral and stop position at switches and P1 connector: replace switches as necessary or disconnect external stop device if so equipped; Measure for voltage at fuel pump while genset is not running or being primed: replace control as necessary
Starter Engages – DisengagesBattery connections, battery, charging system, start/stop switches, engine compressionMeasure battery voltage at battery and genset; Inspect battery connections and cables for cleanliness, tightness and damage: clean, tighten and repair connections and cables as necessary; Check electrolyte level and hydrometer reading in maintenance type batteries: replace electrolyte and recharge or replace battery as necessary; Disconnect genset control P1 connector, verify P1 pins are fully inserted and inspect pin condition per PSB–676: insert, repair or replace pins as necessary; Reconnect P1 connector and test run genset for fault occurrence: repair or replace pins in connector as necessary; Measure battery voltage at genset while attempting to start from local or remote switch: recharge or replace battery if voltage drops below 9 VDC, test and service genset battery charger if so equipped, increase battery cable size or run parallel cables; Measure battery voltage and check for charger increase while genset is running
No AC Power – Genset Running, Status LED On Steady or Flashing RapidlyCircuit breakers, Engine Run Only mode due to faulty generatorStatus light on – Measure AC output at genset circuit breaker: reset or turn on genset circuit breaker, diagnose faulty loads as necessary; HGJAD, E, F Models – (Rapid flashing status light – Engine Run Only mode): Remove connector P1 from control and re-install and try to start genset: inspect, repair or replace P1 connector pins as necessary; While running in Engine Run Only mode externally excite field with 12 VDC or 24 VDC and measure main and quadrature winding AC output; Measure field, quadrature and main winding resistance: clean slip rings, replace brushes, repair harness and replace rotor or stator as necessary; Measure field, quadrature and main winding resistance to ground: clean slip rings, replace brushes, repair harness and replace rotor or stator as necessary; Measure field, quadrature and main winding resistance to each other: clean slip rings, replace brushes, repair harness and replace rotor or stator as necessary; Check brush alignment per PSB-682a
Genset cranks but does not start – no fault codeNot holding start switch long enough to cause faultCheck and record last fault code; Crank genset and hold switch until control stops cranking and displays fault code (approximately 30 seconds): troubleshoot fault code and reference last fault code recorded above if necessary
Genset runs but stops when switch is released – no fault codeNot holding start switch long enough to cause faultCheck and record last fault code; Start genset and hold switch until control shuts down and displays fault code (approximately 30 seconds): troubleshoot fault code and reference last fault code recorded above if necessary
The genset does not start after two or three triesWait 5 seconds for the control to reset before trying again. See Section 11. Troubleshooting
Status indicator light dead (genset locked out, faulty connections, no battery voltage)Genset locked out; faulty connections; no battery voltageUnlock the genset with the lockout switch in the cab and/or boom bucket; Try the genset Start Switch if the remote Start Switch does not work, and vice versa; Clean and tighten the positive (+) and negative (–) battery cable connections at the battery, vehicle frame and genset; Recharge or replace the battery. Refer to the battery manufacturer's recommendations.
Starting batteries run down (marginal batteries, connections, or charging system or, parasitic loads)Marginal batteries; connections; charging system; parasitic loadsClean and tighten the positive (+) and negative (–) battery cable connections at the battery, vehicle frame and genset; Recharge or replace the battery. Refer to the battery manufacturer's recommendations; Have a battery charging system installed or serviced in the vehicle.
Starter engages-disengages (cranking voltage dips below 6 volts—low battery charge, poor connections, long cables)Cranking voltage dips below 6 volts; low battery charge; poor connections; long cablesHave the vehicle propulsion engine running while trying to start the genset—the battery charging alternator may be able to maintain starting voltage high enough to get the genset started; Clean and tighten the positive (+) and negative (–) battery cable connections at the battery, vehicle frame and genset; Recharge or replace the battery. Refer to the battery manufacturer's recommendations; Increase battery cable size or run parallel cables.
No power—genset running, status light on (line circuit breaker OFF, or tripped due to short circuit or overload)Line circuit breaker OFF, or tripped due to short circuit or overloadTurn on or reset the line circuit breaker on the genset (Page 10); Turn on or reset the line circuit breakers on the main distribution panel in the vehicle.
Genset Starts or Stops Without Command — No Fault CodeLow battery voltage; shorted harness connection; faulty start/stop switch; Auto Gen Start (AGS) is enabledCheck last fault and record; Measure battery voltage at battery and genset; Inspect battery connections and cables for cleanliness, tightness and damage: clean, tighten and repair connections and cables as necessary; Check electrolyte level and hydrometer reading in maintenance type batteries: replace electrolyte and recharge or replace battery as necessary; Disconnect genset control P1 connector, verify P1 pins are fully inserted and inspect pin condition per PSB-676: insert, repair or replace pins as necessary; Reconnect P1 connector and test run genset for symptom: repair or replace pins in connector as necessary; Measure battery voltage at genset while attempting to start from local or remote switch: recharge or replace battery if voltage drops below 9 VDC, test and service genset battery charger if so equipped, increase battery cable size or run parallel cables; Measure battery voltage and check for charger increase while genset is running; Measure for continuity change across start/stop switch between neutral and start position and neutral and stop position at switches and at connector P1: reconnect or repair connections, replace switches as necessary; Measure for continuity from start and stop inputs to ground at switches and at connector P1: Repair or replace damaged harness; Determine if AGS is installed and enabled (AGS will command start and stop based on its own settings): disable AGS or explain AGS function to customer (see PSB-666)
Genset Shuts Down and may restart but shuts down again — No Fault CodeBad Plug or Not using Resistor style spark plugsCheck plug to see if it is not functioning, If so replace; Check for non-resistor spark plugs. Resistor and Non-Resistor plugs look a like except for the model numbers. Typically a resistor plug will have an "R" in the nomenclature such as W16EXR-U11 versus the non-resistor plug version W16EX-U11. Replace with Resistor Plug. The use of non-resistor plugs in place of resistor plugs in products which use magneto style ignitions and or sensitive electronic equipment can cause odd symptoms. When the spark jumps the gap it produces a significant RFI (Radio Frequency Interference) surge which can interrupt magneto ignitions and electronic controls
Genset Shuts Down With Fault Code — No Cause DeterminedThe HGJAD genset has software with an ERO (Engine Run Only) function. The set requires the control to operate the fuel injection system and a by-pass tester cannot be used to perform addition tests like a dynamic stator/rotor testHGJAD Solution: Put 12 or 24 VDC to the brushes and check the AC output at the Q windings and the main windings; Using the chart below, determine the appropriate AC output voltages with the corresponding DC input to the field. Note: A flying short/open test may also be performed on the rotor when the set is in the ERO mode, by verifying the circuit between the brushes and ground is an open circuit. HGJAA Solution: Temporarily replace the control with the HGJAD control, part number 300-5047, and follow the HGJAD Solution located in the section above; Due to the differences in software, when the trouble shooting is complete, you must reinstall the original control to maintain proper operation and warranty status
No Response — Status Indicator Light DeadLow/No battery voltage; poor battery connection; faulty battery; open harness connection; faulty start/stop switch; faulty LEDMeasure battery voltage at battery, at genset and at connector P1: reconnect, clean, repair and replace connections as necessary; Measure battery voltage at genset while attempting to start or prime from local or remote switch: recharge or replace battery if voltage drops below 9 VDC, test and service genset battery charger if so equipped, increase battery cable size or run parallel cables; Measure for continuity change across start/stop switch between neutral and start position and neutral and stop position at switches and at connector P1: reconnect or repair connections, replace switches as necessary; Test switches LED by energizing with 12 VDC: replace switches as necessary; Disconnect genset control P1 connector, verify P1 pins are fully inserted and inspect pin condition per PSB-676: insert, repair or replace pins as necessary; Reconnect P1 connector and test run genset for start and prime operation: replace control as necessary
Starting Batteries Run DownBattery connections; battery; charging system; excessive cranking; excessive priming
Genset Cranks But Does Not Start — No Fault CodeNot holding start switch long enough to cause faultCheck and record last fault code; Crank genset and hold switch until control stops cranking and displays fault code (approximately 30 seconds): troubleshoot fault code and reference last fault code recorded above if necessary
Genset Runs But Stops When Switch Is Released — No Fault CodeNot holding start switch long enough to cause faultCheck and record last fault code; Start genset and hold switch until control shuts down and displays fault code (approximately 30 seconds): troubleshoot fault code and reference last fault code recorded above if necessary
STATUS INDICATOR LIGHT DEADGenset locked out, faulty connections, no battery voltageUnlock the genset with the lockout switch in the cab and/or boom bucket; Try the genset Start Switch if the remote Start Switch does not work, and vice versa; Clean and tighten the positive (+) and negative (-) battery cable connections at the battery, vehicle frame and genset; Recharge or replace the battery. Refer to the battery manufacturer's recommendations.
STARTING BATTERIES RUN DOWNMarginal batteries, connections, or charging system or, parasitic loadsClean and tighten the positive (+) and negative (-) battery cable connections at the battery, vehicle frame and genset; Recharge or replace the battery. Refer to the battery manufacturer's recommendations; Have a battery charging system installed or serviced in the vehicle.
STARTER ENGAGES-DISENGAGESCranking voltage dips below 6 volts—low battery charge, poor connections, long cablesHave the vehicle propulsion engine running while trying to start the genset—the battery charging alternator may be able to maintain starting voltage high enough to get the genset started; Clean and tighten the positive (+) and negative (-) battery cable connections at the battery, vehicle frame and genset; Recharge or replace the battery. Refer to the battery manufacturer's recommendations; Increase battery cable size or run parallel cables.
NO POWER—GENSET RUNNING, STATUS LIGHT ONLine circuit breaker OFF, or tripped due to short circuit or overloadTurn on or reset the line circuit breaker on the genset (Page Section 3.10); Turn on or reset the line circuit breakers on the main distribution panel in the vehicle.

Fault codes and symptom→remedy steps extracted from this model’s service/owner documentation; verify against the official manual before servicing.

Common questions

Cummins/Onan 5.5 HGJAD: PROCESSOR SHUTDOWN — what causes it?

Documented causes: Microprocessor ROM error during self-test; Microprocessor RAM error during self-test; Microprocessor malfunction. See the table for the matching fixes.

Cummins/Onan 5.5 HGJAD: OVERPRIME SHUTDOWN — what causes it?

Documented causes: Prime mode exceeded 3 minutes; While running, EGT temp falls below 60C (140F) for 2 minutes - OR - if EGT temperature is not above 60C (140F) after 2 minutes from starting, set will shut down; (Prime mode exceeded 3 minutes). See the table for the matching fixes.

Cummins/Onan 5.5 HGJAD: Exhaust Gas Temp Shutdown/Fault — what causes it?

Documented causes: Exhaust gas temperatures reach 650C (1202F) for 2 secs when the set is running; With the set running and/or startup - control reads 1000C (1832F) for 1 second; (Exhaust gas temperatures reach 650C (1202F) for 2 secs when the set is running). See the table for the matching fixes.