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Onan Controller

The Onan is a generator-set controller. It is used on generator sets from Cummins/Onan, including the MDE.

4
Generator sets
Cummins/Onan
Brand
30–900 kW
Power range
Diesel
Fuel

Generator sets using this controller

4

Also fitted to: Cummins/Onan DFJA (KTA38-G1), Cummins/Onan DFJB (KTA38-G2), Cummins/Onan DFJC (KTA38-G3).

Troubleshooting

21

Fault codes

CodeMeaningRemedy
FAULT 1 or FAULT 2The FAULT 1 or FAULT 2 fault lamp lights. Engine shuts down immediately, or engine runs for several seconds and then shuts down, or engine continues to run.The nature of the fault is an optional selection that is determined when the set installation is designed. The undesignated fault functions may also be programmed for non-shutdown or non-time delay.

Symptoms & remedies

SymptomCauseRemedy
Engine runs and then shuts down, OVERSPEED lamp lights.Contact your Dealer or Distributor for service.
Engine runs, shuts down and cranks for 75-seconds. Cranking cycle stops; fault lamp lights.Check fuel supply.
Engine runs, shuts down, cranks for 75-seconds, cranking cycle stops, overcrank light ON.Check fuel supply.
Engine starts from generator control panel but will not start automatically or from a remote panel.Note: The Run/Stop/Remote switch must be in the Remote position for automatic or remote starting. Engine wil not crank. Indicates possible fault with control or starting system. Check for the following conditions: a. Fault lamp on. Correct fault and reset control. b. Poor battery cable connections. Clean the battery cable terminals and tighten connections. c. Replace the battery if necessary. d. Contact your Dealer or Distributor for assistance if none of the above.
Engine stops cranking and fault lamp lights, after cranking approximately 75 seconds.See engine service manual for troubleshooting fuel system. After correcting problem, reset engine.
Engine will not crank.Indicates possible fault with control or starting system. Check for the following conditions: a. Fault lamp on. Correct fault and reset control. b. Poor battery cable connections. Clean the battery cable terminals and tighten connections. c. Replace the battery if necessary. d. Contact your Dealer or Distributor for assistance if none of the above.
Fault lamp lights and engine shuts down after running for a period.A. Oil level. Engine will shut down if sensor is closed. b. Check engine manual for troubleshooting oil system. c. High engine temperature. Check coolant level; check water flow, pump belts for tightness. See engine manual for troubleshooting cooling system. d. Check for faulty oil pressure sensor or faulty high engine temperature sensor.
Fault lamp lights but no fault exists.The monitor board or a sensor may be at fault. Contact your Dealer or Distributor for service.
Fault lamp lights immediately after engine starts.Overspeed condition as engine starts.
Fault lamp lights, no fault exists.To check a no-fault condition, disconnect leads from TB11 terminals 29, 30 and 31. If fault lamp lights with leads disconnected, replace engine monitor board. Reconnect leads.
HI ENG TEMP lamp lights. Engine shuts down.Allow engine to cool down completely before proceeding with the f
LO ENG TEMP lamp lights. Set is in standby mode but is not operating.Lamp lights when engine coolant temperature is 70°F (21°C) or lower. Since the lamp goes out after the engine warms up, there should be no cause for alarm even during initial generator set operation.
LO FUEL Lamp lights. Engine shuts down and LO OIL PRES lamp lights.Indicates engine has run out of fuel. Check fuel level and replenish as required.
LO FUEL lamp lights. Engine continues to run.Indicates diesel fuel supply is running low. Check fuel supply and replenish as required.
LO OIL PRES lamp lights. Engine shuts down.Check oil level, lines and filters. If oil system is okay but oil level is low, replenish. Reset control and restart. Contact your Dealer or Distributor if oil pressure is not in the range of 35 to 55 psi (21 to 379 kPa).
No-AC output voltage.Field breaker is tripped. Reset breaker.
OVERCRANK lamp lights and engine stops cranking.A. Check for empty fuel tank, fuel leaks, or plugged fuel lines and correct as required. b. Check for dirty fuel filter and replace if necessary (see Maintenance section). c. Check for dirty or plugged air filter and replace if necessary (see Maintenance section). d. Refer to Step 5. e. Reset the control and restart after correcting the problem. Contact your Dealer or Distributor for service if none of the above.
PRE Hi ENGINE TEMP lamp lights. Engine continues to operate.A. Reduce load if possible by turning off non-critical loads. b. Check air inlets and outlets and remove any obstructions to airflow. c. Open doors or windows in generator area to increase ventilation.
PRE LO OIL PRES lamp lights. Engine continues to operate.Check oil level, lines and filters. If oil system is okay but oil level is low, replenish. Reset control and restart. Contact your Dealer or Distributor if oil pressure is not in the range of 35 to 55 psi (21 to 379 kPa).
SWITCH OFF lamp flashes.Indicates Run/Stop/Remote switch is in the STOP position which will prevent automatic starting if an automatic transfer switch is used. Move the Run/Stop/ Remote switch to the Remote position for automatic starting.

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.