Cummins/Onan HDKC troubleshooting: 87 fault codes and 35 symptom-cause-remedy entries from the manufacturer's own service documentation.
Cummins/Onan HDKC — full specs, parts & maintenance.
All Cummins/Onan fault codes →
| Code | Meaning | Cause | Remedy |
|---|---|---|---|
| 1 | Engine Over Temperature — Indicates that, during normal operation, the engine coolant temperature exceeded 115°C (239°F) for 10 seconds. | Check engine coolant level: if coolant level is low, add coolant as necessary and repair any leaks; Check for blockages: if an air inlet or outlet opening on the bottom of the generator set is blocked, remove objects; if dirt is fouling the radiation fins, clean dirt out; Reduce load: reduce the number of connected appliances, especially air conditioners and battery chargers | |
| 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 | |
| 3 | Service Check | See second-level fault code. | |
| 4 | Over Crank — Indicates that cranking exceeded 30 seconds without engine starting. | Check fuel level: if fuel level is low, fill the fuel tank; prime the engine fuel system by positioning the control switch to STOP/PRIME for 30 seconds; Check air filter element: replace the air filter if dirty; Replace engine oil with oil of proper viscosity for the ambient temperature; Check fuel fittings: tighten any fuel fitting if there is a fuel or air leak, reprime the engine fuel system by positioning the control switch to STOP/PRIME for 30 seconds; Replace fuel filter | |
| 12 | Over Voltage — Indicates the control is unable to maintain rated voltage. | Contact local dealer or distributor | |
| 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 | |
| 14 | Over Frequency — Indicates the engine governor is unable to maintain rated frequency. | Contact local dealer or distributor | |
| 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 | |
| 19 | Governor Actuator — Indicates the control sensed an open or shorted circuit. | Contact local dealer or distributor | |
| 22 | Governor Actuator Overload — Indicates the duration of operation is near full-duty cycle beyond design limit. | Reduce load: reduce the number of connected appliances, especially air conditioners and battery chargers; Check air filter element: replace the air filter if dirty; Check exhaust system: if exhaust system is blocked, remove blockage | |
| 27 | Voltage Sense — Indicates the control is unable to sense output voltage. | Contact local dealer or distributor | |
| 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 | |
| 32 | Low Cranking Speed — Indicates that cranking speed is less than 180 RPM for more than 2 seconds. | Check battery: clean and tighten the positive (+) and negative (–) battery cable connections at the battery and at the generator set; recharge or replace the battery; Replace engine oil with oil of proper viscosity for the ambient temperature | |
| 35 | Control Card Failure — Indicates that a microprocessor EEPROM error occurred during self test. | Contact local dealer or distributor | |
| 36 | Engine Stopped — Indicates that the engine stopped without receiving a command from the control. | Check fuel level: if fuel level is low, fill the fuel tank; prime the engine fuel system by positioning the control switch to STOP/PRIME for 30 seconds; Check air filter element: replace the air filter if dirty; Check for mechanical damage | |
| 38 | Over Current (Field Overload) — Indicates low power factor loads. | Reduce load: reduce the number of connected appliances, especially air conditioners and battery chargers; Check appliances for proper operation: have air conditioners and other appliances checked for proper operation | |
| 41 | Generator Rotor — Indicates control is unable to sense field or output voltage. | Contact local dealer or distributor | |
| 42 | Processor — Indicates that a microprocessor ROM error occurred during self test. | Contact local dealer or distributor | |
| 43 | Processor — Indicates that a microprocessor RAM error occurred during self test. | Contact local dealer or distributor | |
| 45 | Speed Sense — Indicates the control is unable to sense quadrature frequency. | Contact local dealer or distributor | |
| 48 | Generator Field Sense — Indicates the control is unable to sense field voltage. | Contact local dealer or distributor | |
| 57 | Over Prime — Indicates that priming exceeded 3 minutes. | Check control switch: check for and remove any object that may be holding either control switch (remote or generator set) in the STOP/PRIME position | |
| Code 1 | Engine Over Temperature | ||
| Code 2 | Low Oil Pressure | ||
| Code 3 | Service Check | ||
| Code 4 | Over Crank | ||
| Code 12 | Over Voltage | ||
| Code 13 | Under Voltage | ||
| Code 14 | Over Frequency | ||
| Code 15 | Under Frequency | ||
| Code 19 | Governor Actuator | ||
| Code 22 | Governor Actuator Overload | ||
| Code 27 | Voltage Sense | ||
| Code 29 | High Battery Voltage | ||
| Code 32 | Low Cranking Speed | ||
| Code 35 | Control Card Failure | ||
| Code 36 | Engine Stopped | ||
| 1 | Engine over temperature — During normal operation engine coolant temperature exceeded 239° F [115° C] for 10 seconds | Check engine coolant level, add coolant as necessary and repair any leaks; Check for and remove any objects blocking the air inlet or outlet openings in the bottom of the genset and clean out dirt fouling the radiator passages; Run fewer appliances at the same time to keep down engine temperature. (Note that high altitude and high ambient temperature decrease engine cooling capacity.); Look for loose or broken fan belts and have them serviced. | |
| 2 | Low oil pressure — During normal operation engine oil pressure dropped to less than 14 psi for 3 seconds—switch closed | Check engine oil level, add oil as necessary and repair any leaks; Drain the excess oil if the level is above Full on the dipstick. If the level is too high the crankshaft can whip the oil into foam, which the pump can't pump. | |
| 3 | Service check — A second-level fault occurred | Check the second-level fault code by momentarily pressing Stop. The second-level fault will be one of the following in this table. | |
| 4 | Over crank — First-level fault code—Cranking time exceeded 35 seconds | Check fuel level and refill as necessary. (Note: The genset fuel pickup is probably higher than the vehicle engine fuel pickup.); Prime the engine fuel system for one minute (p. 2-4); Check the engine air filter and remove any blockage (p. 3-4); Change the engine oil to oil of the proper viscosity for the ambient temperature. High oil viscosity can slow down cranking speed; Check all fuel fittings for fuel and air leaks and tighten as necessary. Reprime; Replace the fuel filter (p. 3-6). | |
| 12 | Over voltage — After voltage regulation was enabled Output Voltage jumped to more than 150 VAC [125% of rated] for 75 milliseconds or to more than 138 VAC [115% of rated] for 3 seconds | See an authorized Onan dealer. | |
| 13 | Under voltage — After voltage regulation was enabled Output Voltage fell to less than 108 VAC [90% of rated] for 5 seconds | Turn OFF the line circuit breaker on the operator's console. If the genset now runs, run it with fewer connected loads. | |
| 14 | Over frequency — After the starter was engaged Frequency jumped to more than 70 Hz for 40 milliseconds or to more than 66 Hz for 6 seconds | Check for a tripped genset circuit breaker, reset it if necessary, and run with fewer connected loads. (A breaker tripping under load can cause genset frequency to overshoot.); Check all fuel fittings for fuel and air leaks and tighten as necessary. Reprime. (Air bubbles can disrupt frequency.) | |
| 15 | Under frequency — During normal operation Frequency fell to less than 54 Hz for more than 8 seconds | Push the line circuit breaker to OFF and restart the genset. If the genset now runs, run it with fewer connected loads, especially those with high motor starting loads such as air conditioners; Check all fuel fittings for fuel and air leaks and tighten as necessary. Reprime. (Air bubbles can disrupt frequency.); Replace the engine air filter and clean the spark-arrest muffler (p. 3-4); Replace the fuel filter (p. 3-6). | |
| 19 | Actuator shorted or open — At startup the Controller sensed an open or shorted governor actuator/harness | See an authorized Onan dealer. | |
| 22 | Actuator overload — Due to connected overload or low engine performance, the Controller maintained the governor actuator at full-duty cycle—maximum pulse-width-modulated square-wave signal [PWM]—for 60 consecutive seconds | Reduce the number of appliances running at the same time, especially those with high motor starting loads such as air conditioners; Check all fuel fittings for fuel and air leaks and tighten as necessary. Reprime; Replace the engine air filter and clean the spark-arrest muffler (p. 3-4); Replace the fuel filter (p. 3-6). | |
| 24 | Faulty engine temperature sender — After 10 minutes of normal operation the Controller checked for and sensed an open temperature sender/harness | See an authorized Onan dealer. | |
| 27 | VAC sense lost — The Controller lost VAC sensing during normal voltage regulation when the field was functioning normally and frequency was at least 40 Hz | See an authorized Onan dealer. | |
| 29 | High battery voltage — During startup the Controller sensed that battery system voltage was greater than 19.2 volts for 5 milliseconds or greater than 19.2 volts for 1 second will running | 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 booster charge rate. | |
| 32 | Starting fault — The Controller could not detect cranking speed [quadrature zero crossings] for 12 seconds | Have the vehicle propulsion engine running while trying to start the genset. Its charging alternator may be able to maintain a high enough battery terminal voltage to start the genset; Service the battery as necessary by cleaning and tightening connections, recharging or replacing the battery or replacing damaged battery cables; Change the engine oil to oil of the proper viscosity for the ambient temperature. High oil viscosity can slow down cranking speed. | |
| 35 | EE checksum fault — During startup the genset Controller detected an EE memory error | See an authorized Onan dealer. | |
| 36 | Mechanical fault — The Controller declared this fault because engine speed fell below 1000 RPM for 0.5 seconds, though not by Controller action | Check fuel level and refill as necessary. (Note: The genset fuel pickup is probably higher than the vehicle engine fuel pickup.); Prime the engine fuel system for one minute (p. 2-4); Check all fuel fittings for fuel and air leaks and tighten as necessary. Reprime; Check the engine air filter and remove any blockage (p. 3-4); Replace the fuel filter (p. 3-6). | |
| 38 | Field overload — During normal voltage regulation Field Voltage exceeded 180 VAC for 10 seconds | Reduce the number of air conditioners running at the same time, and other appliances that cause low power factor. (The lower the power factor of a motor or compressor, the more current it draws per kilowatt. The genset Controller, in turn, must boost field voltage to meet the higher demand for current imposed by low power factor.); Have the air conditioners and other appliances checked for proper operation. (A locked compressor rotor can cause a very low power factor.) | |
| 41 | Generator rotor short — While field flashing during cranking, the Controller sensed that the rotor circuit was shorted to ground | See an authorized Onan dealer. | |
| 42 | ROM fault — During startup the genset Controller detected a ROM memory error | See an authorized Onan dealer. | |
| 43 | RAM fault — During startup the genset Controller detected a RAM memory error | See an authorized Onan dealer. | |
| 45 | Speed sense lost — After start disconnect the Controller lost speed sense [quadrature zero crossings] for 0.25 seconds | See an authorized Onan dealer. | |
| 48 | Loss of field sense — The field sense circuit on the Controller circuit board failed during normal voltage regulation | See an authorized Onan dealer. | |
| 57 | Overprime — The local or remote control switch was held in the Prime position for more than 3 minutes | Check for and remove any object that may be holding either control switch (remote or local) in the prime position. | |
| OVER CRANK | OVER CRANK—CODE NO. 4 | Cranking time exceeded 35 seconds | 1. Check fuel level and refill as necessary. (Note: The genset fuel pickup is probably higher than the vehicle engine fuel pickup.) 2. Prime the engine fuel system for one minute (p. 2-4). 3. Check the engine air filter and remove any blockage (p. 3-4). 4. Change the engine oil to oil of the proper viscosity for the ambient temperature. High oil viscosity can slow down cranking speed. 5. Check all fuel fittings for fuel and air leaks and tighten as necessary. Reprime. 6. Replace the fuel filter (p. 3-6). |
| NO. 15 | During normal operation Frequency fell to less than 54 Hz for more than 8 seconds | Push the line circuit breaker to OFF and restart the genset. If the genset now runs, run it with fewer connected loads, especially those with high motor starting loads such as air conditioners. Check all fuel fittings for fuel and air leaks and tighten as necessary. Reprime. Replace the engine air filter and clean the spark-arrest muffler (p. 3-4). Replace the fuel filter (p. 3-6). | |
| NO. 19 | At startup the Controller sensed an open or shorted governor actuator/harness | See an authorized Onan dealer. | |
| NO. 22 | Due to connected overload or low engine performance, the Controller maintained the governor actuator at full-duty cycle—maximum pulse-width-modulated square-wave signal [PWM]—for 60 consecutive seconds | Reduce the number of appliances running at the same time, especially those with high motor starting loads such as air conditioners. Check all fuel fittings for fuel and air leaks and tighten as necessary. Reprime. Replace the engine air filter and clean the spark-arrest muffler (p. 3-4). Replace the fuel filter (p. 3-6). | |
| NO. 24 | After 10 minutes of normal operation the Controller checked for and sensed an open temperature sender/harness | See an authorized Onan dealer. | |
| NO. 27 | The Controller lost VAC sensing during normal voltage regulation when the field was functioning normally and frequency was at least 40 Hz | See an authorized Onan dealer. | |
| NO. 29 | During startup the Controller sensed that battery system voltage was greater than 19.2 volts for 5 milliseconds or greater than 19.2 volts for 1 second while running | 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 booster charge rate. | |
| NO. 32 | The Controller could not detect cranking speed [quadrature zero crossings] for 12 seconds | Have the vehicle propulsion engine running while trying to start the genset. Its charging alternator may be able to maintain a high enough battery terminal voltage to start the genset. Service the battery as necessary by cleaning and tightening connections, recharging or replacing the battery or replacing damaged battery cables. Change the engine oil to oil of the proper viscosity for the ambient temperature. High oil viscosity can slow down cranking speed. | |
| NO. 35 | During startup the genset Controller detected an EE memory error | See an authorized Onan dealer. | |
| NO. 36 | The Controller declared this fault because engine speed fell below 1000 RPM for 0.5 seconds, though not by Controller action | Check fuel level and refill as necessary. (Note: The genset fuel pickup is probably higher than the vehicle engine fuel pickup.) Prime the engine fuel system for one minute (p. 2-4). Check all fuel fittings for fuel and air leaks and tighten as necessary. Reprime. Check the engine air filter and remove any blockage (p. 3-4). Replace the fuel filter (p. 3-6). | |
| NO. 38 | During normal voltage regulation Field Voltage exceeded 180 VAC for 10 seconds | Reduce the number of air conditioners running at the same time, and other appliances that cause low power factor. (The lower the power factor of a motor or compressor, the more current it draws per kilowatt. The genset Controller, in turn, must boost field voltage to meet the higher demand for current imposed by low power factor.) Have the air conditioners and other appliances checked for proper operation. (A locked compressor rotor can cause a very low power factor.) | |
| NO. 41 | While field flashing during cranking, the Controller sensed that the rotor circuit was shorted to ground | See an authorized Onan dealer. | |
| NO. 42 | During startup the genset Controller detected a ROM memory error | See an authorized Onan dealer. | |
| NO. 43 | During startup the genset Controller detected a RAM memory error | See an authorized Onan dealer. | |
| NO. 45 | After start disconnect the Controller lost speed sense [quadrature zero crossings] for 0.25 seconds | See an authorized Onan dealer. | |
| NO. 48 | The field sense circuit on the Controller circuit board failed during normal voltage regulation | See an authorized Onan dealer. | |
| NO. 57 | The local or remote control switch was held in the Prime position for more than 3 minutes | ||
| 2 | Low oil pressure — During normal operation engine oil pressure dropped to less than 14 psi [97 kPa] for 3 seconds—switch closed | Check engine oil level, add oil as necessary and repair any leaks; Drain the excess oil if the level is above Full on the dipstick. If the level is too high the crankshaft can whip the oil into foam, which the pump can't pump. | |
| 12 | Over voltage — After voltage regulation was enabled Output Voltage jumped to more than 125% of rated for 75 milliseconds or to more than 115% of rated for 3 seconds | See an authorized Onan dealer. | |
| 13 | Under voltage — After voltage regulation was enabled Output Voltage fell to less than 90% of rated for 5 seconds | Turn OFF the line circuit breaker on the operator's console. If the genset now runs, run it with fewer connected loads. | |
| 14 | Over frequency — After the starter was engaged Frequency jumped to more than 70 Hz for 40 milliseconds, or to more than 55/66 Hz [50/60 Hz rated] for 6 seconds | Check for a tripped genset circuit breaker, reset it if necessary, and run with fewer connected loads. (A breaker tripping under load can cause genset frequency to overshoot.); Check all fuel fittings for fuel and air leaks and tighten as necessary. Reprime. (Air bubbles can disrupt frequency.) | |
| 15 | Under frequency — During normal operation Frequency fell to less than 44/54 Hz [50/60 Hz rated] for more than 8 seconds | Push the line circuit breaker to OFF and restart the genset. If the genset now runs, run it with fewer connected loads, especially those with high motor starting loads such as air conditioners; Check all fuel fittings for fuel and air leaks and tighten as necessary. Reprime. (Air bubbles can disrupt frequency.); Replace the engine air filter and clean the spark-arrest muffler (p. 3-4); Replace the fuel filter (p. 3-6). | |
| 38 | Field overload — During normal voltage regulation Field Voltage exceeded 150 VAC for 10 seconds | Reduce the number of air conditioners running at the same time, and other appliances that cause low power factor. (The lower the power factor of a motor or compressor, the more current it draws per kilowatt. The genset Controller, in turn, must boost field voltage to meet the higher demand for current imposed by low power factor.); Have the air conditioners and other appliances checked for proper operation. (A locked compressor rotor can cause a very low power factor.) | |
| CODE NO. 14 | After the starter was engaged Frequency jumped to more than 70 Hz for 40 milliseconds or to more than 66 Hz for 6 seconds | 1. Check for a tripped genset circuit breaker, reset it if necessary, and run with fewer connected loads. 2. Check all fuel fittings for fuel and air leaks and tighten as necessary. Reprime. | |
| CODE NO. 15 | During normal operation Frequency fell to less than 54 Hz for more than 8 seconds | 1. Push the line circuit breaker to OFF and restart the genset. If the genset now runs, run it with fewer connected loads, especially those with high motor starting loads such as air conditioners. 2. Check all fuel fittings for fuel and air leaks and tighten as necessary. Reprime. 3. Replace the engine air filter and clean the spark-arrest muffler (p. 3-4). 4. Replace the fuel filter (p. 3-6). | |
| CODE NO. 19 | At startup the Controller sensed an open or shorted governor actuator/harness | See an authorized Onan dealer. | |
| CODE NO. 22 | Due to connected overload or low engine performance, the Controller maintained the governor actuator at full-duty cycle—maximum pulse-width-modulated square-wave signal [PWM]—for 60 consecutive seconds | 1. Reduce the number of appliances running at the same time, especially those with high motor starting loads such as air conditioners. 2. Check all fuel fittings for fuel and air leaks and tighten as necessary. Reprime. 3. Replace the engine air filter and clean the spark-arrest muffler (p. 3-4). 4. Replace the fuel filter (p. 3-6). |
| Symptom | Cause | Remedy |
|---|---|---|
| Status Indicator Not Working — Indicates that there could be faulty connections or no battery voltage. | Faulty connections or no battery voltage | Check other control switch: try the generator set control switch if the remote control switch start doesn't work, and vice versa; Check battery: clean and tighten the positive (+) and negative (–) battery cable connections at the battery and at the generator set; recharge or replace the battery |
| Starting Batteries Run Down — Indicates problem with batteries, connections, charging system, or parasitic loads. | Problem with batteries, connections, charging system, or parasitic loads | Check battery: clean and tighten the positive (+) and negative (–) battery cable connections at the battery and at the generator set; recharge or replace the battery; Battery charging system: install or service a battery charging system in the vehicle |
| Starter Engages-Disengages — Indicates cranking voltage dips below 6 Volts. | Cranking voltage dips below 6 Volts | Use vehicle to start generator set: run the vehicle propulsion engine while trying to start the generator set—the battery charging alternator may be able to maintain starting voltage high enough to start the generator set; Check battery: clean and tighten the positive (+) and negative (–) battery cable connections at the battery and at the generator set; recharge or replace the battery; Change battery cables: increase battery cable size or run parallel cables |
| Status Indicator Goes Out While Cranking—No Start — Indicates an internal short circuit caused an automatic-reset circuit protective device to trip. | Internal short circuit caused an automatic-reset circuit protective device to trip | Try starting again: if the status indicator flashes and goes out again without the engine starting, call local dealer or distributor |
| No Power—Generator Set Running, Status Light On — Indicates line circuit breaker is OFF, or tripped due to short circuit or overload. | Line circuit breaker is OFF, or tripped due to short circuit or overload | Check line circuit breakers: turn on or reset the line circuit breaker on the generator set; turn on or reset the line circuit breaker on the main distribution panel in the vehicle |
| Generator voltage is deadly | Disable the automatic genset starting feature of an inverter-charger or other automatic starting device before servicing the genset. Generator electrical output connections must be made by a trained and experienced electrician in accordance with applicable codes. The genset must not be connected to the public utility or any other source of electrical power. An approved switching device must be used to prevent interconnections. | |
| No response at control switch | Faulty switch; poor or missing connections; dead battery | Try the genset (local) control switch if there is no response at the remote control switch, and vice versa; Check for 12 VDC across genset battery cable terminal block. Service as necessary by cleaning and tightening battery cable connections, recharging or replacing the battery or replacing damaged or missing battery cables. |
| The starter engages and disengages | Low cranking voltage | Have the vehicle propulsion engine running while trying to start the genset. Its charging alternator may be able to maintain a high enough battery terminal voltage to start the genset; Service the battery as necessary by cleaning and tightening connections, recharging or replacing the battery or replacing damaged battery cables. |
| The starting batteries do not maintain a charge | Marginal battery, battery connections or charging system | Service the battery as necessary by cleaning and tightening connections, recharging or replacing the battery or replacing damaged battery cables; Have the battery recharging system serviced. |
| No AC power when genset is running | A circuit breaker is OFF, tripped or malfunctioning or there are poor AC harness connections | Reset or turn ON genset circuit breaker CB1; Reset or turn ON any other circuit breaker in the AC power supply system. |
| Persistent, audible engine surging—without fault shutdown | Fuel leaks, restrictions or air bubbles | Check all fuel fittings for fuel and air leaks and tighten as necessary. Reprime; Replace the fuel filter (p. 3-6). |
| Persistent, audible engine surging—without fault shutdown | Worn slip rings/brushes, misadjusted or faulty governor, worn generator bearing | |
| ENGINE OVER TEMPERATURE—CODE NO. 1 | During normal operation engine coolant temperature exceeded 239° F [115° C] for 10 seconds | 1. Check engine coolant level, add coolant as necessary and repair any leaks. 2. Check for and remove any objects blocking the air inlet or outlet openings in the bottom of the genset and clean out dirt fouling the radiator passages. 3. Run fewer appliances at the same time to keep down engine temperature. (Note that high altitude and high ambient temperature decrease engine cooling capacity.) 4. Look for loose or broken fan belts and have them serviced. |
| LOW OIL PRESSURE—CODE NO. 2 | During normal operation engine oil pressure dropped to less than 14 psi for 3 seconds—switch closed | 1. Check engine oil level, add oil as necessary and repair any leaks. 2. Drain the excess oil if the level is above Full on the dipstick. If the level is too high the crankshaft can whip the oil into foam, which the pump can’t pump. |
| SERVICE CHECK—CODE NO. 3 | A second-level fault occurred | Check the second-level fault code by momentarily pressing Stop. The second-level fault will be one of the following in this table. |
| OVER VOLTAGE—CODE NO. 12 | After voltage regulation was enabled Output Voltage jumped to more than 150 VAC [125% of rated] for 75 milliseconds or to more than 138 VAC [115% of rated] for 3 seconds | See an authorized Onan dealer. |
| UNDER VOLTAGE—CODE NO. 13 | After voltage regulation was enabled Output Voltage fell to less than 108 VAC [90% of rated] for 5 seconds | Turn OFF the line circuit breaker on the operator’s console. If the genset now runs, run it with fewer connected loads. |
| OVER FREQUENCY—CODE NO. 14 | After the starter was engaged Frequency jumped to more than 70 Hz for 40 milliseconds or to more than 66 Hz for 6 seconds | 1. Check for a tripped genset circuit breaker, reset it if necessary, and run with fewer connected loads. (A breaker tripping under load can cause genset frequency to overshoot.) 2. Check all fuel fittings for fuel and air leaks and tighten as necessary. Reprime. |
| No response at control switch | Faulty switch, poor or missing connections, dead battery | Try the genset (local) control switch if there is no response at the remote control switch, and vice versa; Check for 12 VDC across genset battery cable terminal block. Service as necessary by cleaning and tightening battery cable connections, recharging or replacing the battery or replacing damaged or missing battery cables. |
| Persistent, audible engine surging—without fault shutdown | Fuel leaks, restrictions or air bubbles, worn slip rings/brushes, misadjusted or faulty governor, worn generator bearing | Check all fuel fittings for fuel and air leaks and tighten as necessary. Reprime; Replace the fuel filter (p. 3-6). |
| Cranking time exceeded 35 seconds | 1. Check fuel level and refill as necessary. 2. Prime the engine fuel system for one minute (p. 2-4). 3. Check the engine air filter and remove any blockage (p. 3-4). 4. Change the engine oil to oil of the proper viscosity for the ambient temperature. High oil viscosity can slow down cranking speed. 5. Check all fuel fittings for fuel and air leaks and tighten as necessary. Reprime. 6. Replace the fuel filter (p. 3-6). | |
| Output Voltage jumped to more than 125% of rated for 75 milliseconds or to more than 115% of rated for 3 seconds | See an authorized Onan dealer. | |
| Output Voltage fell to less than 90% of rated for 5 seconds | Turn OFF the line circuit breaker on the operator’s console. If the genset now runs, run it with fewer connected loads. | |
| Frequency jumped to more than 70 Hz for 40 milliseconds, or to more than 55/66 Hz [50/60 Hz rated] for 6 seconds | 1. Check for a tripped genset circuit breaker, reset it if necessary, and run with fewer connected loads. (A breaker tripping under load can cause genset frequency to overshoot.) 2. Check all fuel fittings for fuel and air leaks and tighten as necessary. Reprime. (Air bubbles can disrupt frequency.) | |
| Frequency fell to less than 44/54 Hz [50/60 Hz rated] for more than 8 seconds | 1. Push the line circuit breaker to OFF and restart the genset. If the genset now runs, run it with fewer connected loads, especially those with high motor starting loads such as air conditioners. 2. Check all fuel fittings for fuel and air leaks and tighten as necessary. Reprime. (Air bubbles can disrupt frequency.) 3. Replace the engine air filter and clean the spark-arrest muffler (p. 3-4). 4. Replace the fuel filter (p. 3-6). | |
| At startup the Controller sensed an open or shorted governor actuator/harness | See an authorized Onan dealer. | |
| Due to connected overload or low engine performance, the Controller maintained the governor actuator at full-duty cycle—maximum pulse-width-modulated square-wave signal [PWM]—for 60 consecutive seconds | 1. Reduce the number of appliances running at the same time, especially those with high motor starting loads such as air conditioners. 2. Check all fuel fittings for fuel and air leaks and tighten as necessary. Reprime. 3. Replace the engine air filter and clean the spark-arrest muffler (p. 3-4). 4. Replace the fuel filter (p. 3-6). | |
| After 10 minutes of normal operation the Controller checked for and sensed an open temperature sender/harness | See an authorized Onan dealer. | |
| The Controller lost VAC sensing during normal voltage regulation when the field was functioning normally and frequency was at least 40 Hz | See an authorized Onan dealer. | |
| During startup the Controller sensed that battery system voltage was greater than 19.2 volts for 5 milliseconds or greater than 19.2 volts for 1 second will running | 1. 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 booster charge rate. | |
| The Controller could not detect cranking speed [quadrature zero crossings] for 12 seconds | 1. Have the vehicle propulsion engine running while trying to start the genset. Its charging alternator may be able to maintain a high enough battery terminal voltage to start the genset. 2. Service the battery as necessary by cleaning and tightening connections, recharging or replacing the battery or replacing damaged battery cables. 3. Change the engine oil to oil of the proper viscosity for the ambient temperature. High oil viscosity can slow down cranking speed. | |
| During startup the genset Controller detected an EE memory error | See an authorized Onan dealer. | |
| The Controller declared this fault because engine speed fell below 1000 RPM for 0.5 seconds, though not by Controller action | ||
| The genset stops | Does the genset operate correctly from the genset controls? If it does not, the problem is in the genset, not the EC-20 controller. See the genset Operator, Installation, and Service Manuals. | |
| The indicator light in the Start/Stop switch turns off | Confirm that the correct connection diagram (Figures 5 - 7) was used, then check EC 30 wiring connections. Confirm that the correct voltages are present on each terminal. Check all terminal connections on both ends of the wiring harness. Are harness connectors properly joined? |
Fault codes and symptom→remedy steps extracted from this model’s service/owner documentation; verify against the official manual before servicing.
Documented causes: Fuel leaks, restrictions or air bubbles; Worn slip rings/brushes, misadjusted or faulty governor, worn generator bearing; Fuel leaks, restrictions or air bubbles, worn slip rings/brushes, misadjusted or faulty governor, worn generator bearing. See the table for the matching fixes.
Documented causes: Faulty switch; poor or missing connections; dead battery; Faulty switch, poor or missing connections, dead battery. See the table for the matching fixes.
Documented causes: Faulty connections or no battery voltage. See the table for the matching fixes.