The A1 is a generator-set controller. It is used on generator sets from Cummins/Onan, including the 3.6MKY, 4MKY, HGJAA and MDKAV.
Also fitted to: Cummins/Onan HGJAA & HGJAD, Cummins/Onan HGJAB & HGJAE, Cummins/Onan HGJAC & HGJAF.
| Code | Meaning | Remedy |
|---|---|---|
| 1 | HIGH ENGINE TEMPERATURE | 1. Add coolant as necessary and repair leaks (Page 18). 2. Replace the engine thermostat, which might not be opening fully (Page 21). 3. Clean the raw water tubes in the heat exchanger, which might be clogged with scale (Page 22). 4. Flush the coolant system to remove coolant passage fouling (Page 18). |
| 1 | HIGH ENGINE TEMPERATURE—CODE NO. 1 (Engine coolant temperature exceed design limit) | 1. Check for and clean a blocked sea water strainer. If above the water line, fill the strainer with water to assist priming. 2. Check engine coolant level and add coolant as necessary. 3. Check for kinked or leaking hoses and reconnect, reroute or replace. 4. Check the V-belt that drives the coolant pump and service as necessary 5. Inspect the siphon break (if provided) for proper operation. 6. Check for a worn raw water impeller and replace as necessary 7. Clean the heat exchanger |
| 1 | Shutdown due to high engine temperature | |
| 1 or 2 digit code | Status light on the generator will repeatedly blink a 1 or 2 digit code after a protective shutdown | |
| 12 | HIGH AC VOLTAGE—CODE NO. 12 (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 service representative. |
| 12 | OVERVOLTAGE | See an authorized Onan dealer. |
| 12 | OVERVOLTAGE FAULT—CODE NO. 12 | See an authorized Onan dealer. |
| 12 | Overvoltage | |
| 13 | LOW AC VOLTAGE—CODE NO. 13 (After voltage regulation was enabled Output Voltage fell to less than 90% of rated for 5 seconds) | Push the genset line circuit breaker OFF. If the genset now runs, reduce the number of loads. |
| 13 | UNDERVOLTAGE | Reduce the number of connected appliances, especially when air conditioners and battery chargers are running. |
| 13 | UNDERVOLTAGE FAULT—CODE NO. 13 | Reduce the number of connected appliances, especially when air conditioners and battery chargers are running. |
| 13 | Undervoltage | |
| 14 | HIGH AC FREQUENCY—CODE NO. 14 (After the starter was engaged Frequency jumped to more than 70 Hz for 40 milliseconds or to more than 2% over nominal 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 and reprime. |
| 14 | OVERFREQUENCY | 1. If the line circuit breaker or any other circuit breaker has tripped, start the genset before resetting the breaker. (Frequency can overshoot when a circuit breaker trips under load.) If the genset continues to run, turn off or disconnect all loads, reset the breaker and bring the loads on one at a time without overloading the genset. 2. Tighten loose fuel line fittings so that air cannot be drawn in by genset lift pump suction. 3. Prime the fuel system to remove air in the fuel lines (Page 8). |
| 14 | OVERFREQUENCY FAULT—CODE NO. 14 | See an authorized Onan dealer. |
| 14 | Overfrequency | |
| 15 | LOW AC FREQUENCY—CODE NO. 15 (During normal operation Frequency fell to less than 90% of nominal for more than 8 seconds) | Push the genset line circuit breaker OFF. If the genset now runs, reduce the number of loads. |
| 15 | UNDERFREQUENCY FAULT—CODE NO. 15 | Reduce the number of connected appliances, especially when air conditioners and battery chargers are running. |
| 15 | Underfrequency | |
| 17 | Fuel Pump Fault | |
| 19 | Governor Actuator (EFI Only) | |
| 2 | LOW OIL PRESSURE | Add engine oil or drain excess oil, as necessary (Page 14). |
| 2 | LOW OIL PRESSURE—CODE NO. 2 (Low oil pressure) | Check engine oil level, add or drain oil as necessary and repair any leaks |
| 2 | Low Oil Pressure Fault | |
| 2 | Shutdown due to low oil pressure | |
| 22 | Governor Actuator Overload (EFI Only) | |
| 23 | Oil Pressure Switch Fault | |
| 27 | VOLTAGE SENSE FAULT—CODE NO. 27 | See an authorized Onan dealer. |
| 27 | Voltage Sense Lost | |
| 29 | HIGH BATTERY VOLTAGE FAULT—CODE NO. 29 | 1. Check battery bank connections and reconnect if necessary so that the 12 volt batteries serving the genset are connected in parallel (12 v |
| 29 | High Battery Voltage | |
| 3 | SERVICE CHECK | Check the second-level shutdown code by pressing STOP once. The second-level shutdown code will have two-digits. The shutdowns are listed below in numerical order. |
| 3 | SERVICE CHECK FAULT—CODE NO. 3 | Check the second-level fault code by pressing STOP once. The second-level fault code will have two-digits. The faults are listed in numerical order in this table. |
| 3 | SERVICE CHECK—CODE NO. 3 (A fault with a 2-Digit Fault Code Number occurred) | Check the 2-Digit fault code by Pushing and Releasing Stop |
| 3 | Service Check Fault | |
| 3 | Service fault | Press Stop once to cause the two-digit shutdown code to blink |
| 31 | Overspeed Fault | |
| 31 | Overspeed Fault (HGJAD, E, F Models Only) | |
| 32 | Low Cranking Speed Sense | |
| 33 | Fault Code 3 - Fault Code 33 | |
| 33 | Fault Code 33 | |
| 35 | Control Card Failure | |
| 36 | Generator Set Stopped Without Fault Condition | |
| 36 | Generator Set Stopped Without Fault Condition - Fault Code 36 | |
| 36 | Genset Stopped Without Fault Condition | |
| 37 | Invalid Set Configuration | |
| 38 | Field Overload (Overvoltage) | |
| 4 | OVERCRANK | 1. Check the fuel tank and fill as necessary. (Note: The arrangement of pickup tubes in the fuel supply tank probably is such that the genset will run out of fuel before the propulsion engines.) 2. Open any closed fuel valves. 3. Remove any blockage in the combustion air inlet (front grille) or exhaust system. 4. Tighten loose fuel line fittings so that air cannot be drawn in by genset lift pump suction. 5. Drain and/or replace the fuel filter (Page 16) and prime the fuel system (Page 8). 6. Drain and/or replace fuel supply system filters and prime the fuel system (Page 8). |
| 4 | OVERCRANK FAULT—CODE NO. 4 | 1. Check and fill the fuel tank, as necessary. (Note: The genset fuel pickup is probably higher than the boat engine pickup.) 2. Prime the engine fuel system by holding the control switch at Stop/Prime for 30 seconds. 3. Open any closed fuel valves. 4. Secure the spark plug lead on the spark plug (Page 20). 5. Replace the spark plug (Page 20). 6. Service the air cleaner (Page 19). |
| 4 | OVERCRANK—CODE NO. 4 (Cranking time exceeded 20 to 60 seconds, depending on ambient temperature) | 1. Check fuel level and refill as necessary. 2. Open any closed fuel supply and return valves. 3. Prime the engine fuel system for at least 30 seconds 4. Service the battery as necessary by cleaning and tightening connections, recharging or replacing the battery or replacing damaged battery cables 5. Replace the fuel filters and reprime 6. Check all fuel fittings for fuel and air leaks, tighten as necessary and reprime. 7. Change the engine oil to oil of the proper viscosity for the ambient temperature |
| 4 | Overcrank | |
| 4 | Shutdown due to a failure to start within the time allowed for cranking | |
| 41 | Alternator Rotor Fault | |
| 41 | Generator Rotor Fault | |
| 42 | Processor Fault | |
| 42 | Processor Fault - Fault Code 42 | |
| 43 | Processor Fault - Fault Code 43 | |
| 45 | Speed Sense Fault | |
| 47 | Ignition Fault | |
| 48 | Field Sense Fault |
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.