The Onan (status indicator switch) is a generator-set controller. It is used on generator sets from Cummins/Onan, including the 5.5 HGJAE and 6.5 HGJAE.
Also fitted to: Cummins/Onan 5.5 HGJAD/HGJAE, Cummins/Onan 7.0 HGJAD/HGJAE.
| Code | Meaning | Cause | Remedy |
|---|---|---|---|
| 1 | High engine coolant temperatures | ||
| 12 | OVERVOLTAGE SHUTDOWN | Controller unable to maintain rated voltage | See an authorized Onan dealer. |
| 12 | Over Voltage — Indicates the control is unable to maintain rated voltage. | Contact local dealer or distributor. | |
| 12 | Overvoltage | ||
| 12 | Overvoltage shutdown — Controller unable to maintain rated voltage | Controller unable to maintain rated voltage | See an authorized Onan dealer. |
| 12 | Overvoltage — 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 minutes | Genset loads; Inverter/Charger; wire connections; AC sense transformer; windings | Verify 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 |
| 13 | AC voltage S1–S2 less than 108 VAC for 5 continuous seconds | Genset loads, Inverter/Charger, wire connections, generator drive system, windings, AC sense transformer, windings | Verify 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 |
| 13 | UNDERVOLTAGE SHUTDOWN | Controller unable to maintain rated voltage | Reduce the number of connected appliances, especially when air conditioners and battery chargers are running. |
| 13 | Under Voltage — Indicates the control is unable to maintain rated voltage. | Reduce load: reduce the number of connected appliances, especially air conditioners and battery chargers (review load management in Loading the Generator Set). | |
| 13 | Undervoltage shutdown — Controller unable to maintain rated voltage | Controller unable to maintain rated voltage | Reduce the number of connected appliances, especially when air conditioners and battery chargers are running. |
| 13 | Undervoltage — AC voltage S1−S2 less than 108 VAC for 5 continuous seconds | Genset loads; Inverter/Charger; wire connections; generator drive system; windings; AC sense transformer; windings | Verify 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 |
| 14 | OVERFREQUENCY SHUTDOWN | Engine governor unable to maintain rated frequency | See an authorized Onan dealer. |
| 14 | Over Frequency — Indicates the engine governor is unable to maintain rated frequency. | Contact local dealer or distributor. | |
| 14 | Overfrequency | Genset loads, Inverter/Charger, engine governor function, fuel supply, air fuel mixture, exhaust system, choke, demand regulator, carburetor, generator drive system, generator windings, ignition, wire connections | Verify 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 |
| 14 | Overfrequency shutdown — Engine governor unable to maintain rated frequency | Engine governor unable to maintain rated frequency | See an authorized Onan dealer. |
| 15 | UNDERFREQUENCY SHUTDOWN | Engine governor unable to maintain rated frequency | Reduce the number of connected appliances, especially when air conditioners and battery chargers are running. |
| 15 | Under Frequency — Indicates the engine governor is unable to maintain rated frequency. | Reduce load: reduce the number of connected appliances, especially air conditioners and battery chargers (review load management in Loading the Generator Set). | |
| 15 | Underfrequency | ||
| 15 | Underfrequency shutdown — Engine governor unable to maintain rated frequency | Engine governor unable to maintain rated frequency | Reduce the number of connected appliances, especially when air conditioners and battery chargers are running. |
| 17 | Fuel Pump Fault — Only Active Prior to 2001 − Open fuel pump circuit at control | Wire connections; harness leads; faulty fuel pump | Verify 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 |
| 17 | Fuel pump fault | Wire connections, harness leads, faulty fuel pump | Verify 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 |
| 19 | GOVERNOR ACTUATOR SHUTDOWN | Controller sensed open or shorted circuit | See an authorized Onan dealer. |
| 19 | Governor Actuator (EFI Only) — Shorted or open connection between governor leads after pressing start | Wire 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 |
| 19 | Governor Actuator — Indicates the control sensed an open or shorted circuit. | Contact local dealer or distributor. | |
| 19 | Governor actuator (EFI only) | Wire connections, P1–17, governor actuator | 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 |
| 19 | Governor actuator shutdown — Controller sensed open or shorted circuit | Controller sensed open or shorted circuit | See an authorized Onan dealer. |
| 2 | LOW OIL PRESSURE SHUTDOWN | Low oil pressure cutoff switch did not open | Check engine oil level and add oil as necessary (Page Section 4.2); Drain excess oil (above dipstick Full mark.) |
| 2 | Low Oil Pressure Fault | Low/high oil level; faulty switch; faulty oil pressure relief valve; fault oil pump | Verify 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 |
| 2 | Low Oil Pressure — Indicates that the low oil pressure cutoff switch did not open. | Check engine oil level: if the dipstick indicates oil is low, add oil; if oil is above the full mark on dipstick, drain excess oil. | |
| 2 | Low oil pressure fault | Low/high oil level, faulty switch, faulty oil pressure relief valve, fault oil pump | Verify 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 |
| 2 | Low oil pressure shutdown — First-level shutdown code—Low oil pressure cutoff switch did not open | Low oil pressure cutoff switch did not open | Check engine oil level and add oil as necessary (Page 17); Drain excess oil (above dipstick Full mark.) |
| 22 | GOVERNOR ACTUATOR OVERLOAD SHUTDOWN | Duration of operation at or near full-duty cycle beyond design limit | Reduce 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. |
| 22 | Governor Actuator Overload (EFI Only) — Only active Prior to 2001 − Maximum governor output (PWM) for 10 continuous seconds | Genset loads; Inverter/Charger; wire connections; fuel supply; air fuel mixture; exhaust system; governor actuator; ignition system | Verify 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 |
| 22 | Governor Actuator Overload — Indicates the duration of operation is near full-duty cycle beyond design limit. | Excessive load; dirty air filter element; blocked exhaust system. | Reduce load: reduce the number of connected appliances, especially air conditioners and battery chargers (review load management in Loading the Generator Set); replace the air filter if dirty; if exhaust system is blocked, remove blockage. |
| 22 | Governor actuator overload (EFI only) | Genset loads, Inverter/Charger, wire connections, fuel supply, air fuel mixture, exhaust system, governor actuator, ignition system | Verify 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 |
| 22 | Governor actuator overload shutdown — Duration of operation at or near full-duty cycle beyond design limit | Duration of operation at or near full-duty cycle beyond design limit | Reduce 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. |
| 23 | LOW OIL PRESSURE CUTOFF SWITCH SHUTDOWN | Controller sensed switch still open during start—not a running fault | See an authorized Onan dealer. |
| 23 | Low Oil Pressure Cutoff Switch — Indicates the control sensed that switch is still open during start (not a running start). | Contact local dealer or distributor. | |
| 23 | Low oil pressure cutoff switch shutdown — Controller sensed switch still open during start—not a running fault | Controller sensed switch still open during start—not a running fault | See an authorized Onan dealer. |
| 23 | Oil Pressure Switch Fault — Only Active Prior to 2001 − Continuous open on oil pressure switch input before cranking | Wire connections; faulty switch | Verify 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 |
| 23 | Oil pressure switch fault | Wire connections, faulty switch | |
| 27 | VOLTAGE SENSE SHUTDOWN | Controller unable to sense output voltage | See an authorized Onan dealer. |
| 27 | Voltage Sense Lost | ||
| 27 | Voltage Sense Lost — No Sense Voltage (0 VAC across S1−S2) for 1 continuous second after start disconnect | Genset loads; Inverter/Charger; VAC sense transformer; engine governor function; fuel supply; choke; demand regulator; carburetor; generator windings; ignition; wire connections; temperature | Verify 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 |
| 27 | Voltage Sense — Indicates the control is unable to sense output voltage. | Contact local dealer or distributor. | |
| 27 | Voltage sense shutdown — Controller unable to sense output voltage | Controller unable to sense output voltage | See an authorized Onan dealer. |
| 29 | HIGH BATTERY VOLTAGE SHUTDOWN | Voltage across battery system greater than 19 volts | 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); Select a lower battery boost charge rate. |
| 29 | High Battery Voltage | ||
| 29 | High Battery Voltage — Indicates that voltage across the battery system is greater than 19 Volts. | Check battery bank connections and reconnect if necessary so that the 12 Volt batteries serving the generator set are connected in parallel (12 Volt) rather than in series (24 Volt); select a lower battery boost charge rate. | |
| 29 | High battery voltage | Incorrect battery configuration, wire damage, faulty charger, control | Verify 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 |
| 29 | High battery voltage shutdown — Voltage across battery system greater than 19 volts | Voltage across battery system greater than 19 volts | 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); Select a lower battery boost charge rate. |
| 3 | SERVICE CHECK SHUTDOWN | Indicates fault with second-level shutdown code | Check 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. |
| 3 | Service Check | See second-level fault code. | |
| 3 | Service Check Fault — Single-Digit Fault to indicate shutdown due to a Two-Digit Fault | Any Two-Digit Fault Code | Verify 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 |
| 3 | Service check fault | Any Two-Digit Fault Code | Verify 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 |
| 3 | Service check shutdown — First-level shutdown code—Indicates fault with second-level shutdown code | Indicates fault with second-level shutdown code | Check 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. |
| 31 | OVERSPEED SHUTDOWN | Engine speed greater than 3400 rpm | See an authorized Onan dealer. |
| 31 | Over Speed — Indicates that engine speed is greater than 3400 RPM. | Contact local dealer or distributor. | |
| 31 | Overspeed Fault (HGJAD, E, F Models Only) | ||
| 31 | Overspeed 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 connections | Verify 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 |
Fault codes and symptom→remedy steps extracted from this controller’s service/owner documentation; verify against the official manual before servicing. Aggregated from the service documentation of generator sets built on this controller.