Cummins/Onan DYC Series troubleshooting: 21 symptom-cause-remedy entries from the manufacturer's own service documentation.
Cummins/Onan DYC Series — full specs, parts & maintenance.
All Cummins/Onan fault codes →
| Symptom | Cause | Remedy |
|---|---|---|
| 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 monitor relay by placing Run-Stop/Reset-Remote switch to Stop/Reset, then back to the required running position | |
| Fault lamp lights immediately after engine starts | Overspeed condition as engine starts | Check for overspeed condition as engine starts |
| Fault lamp lights and engine shuts down after running for a period | Oil level (engine will shut down if sensor is closed) | Check oil level |
| Fault lamp lights and engine shuts down after running for a period | Oil system fault | Check engine manual for troubleshooting oil system |
| Fault lamp lights and engine shuts down after running for a period | High engine temperature | Check coolant level; check water flow (city water cooled systems); check radiator for free air flow, and fan belts for tightness; See engine manual for troubleshooting cooling system |
| Fault lamp lights and engine shuts down after running for a period | Faulty oil pressure sensor or faulty high engine temperature sensor | Check for faulty oil pressure sensor or faulty high engine temperature sensor |
| Engine runs, shuts down and cranks for 75 seconds. Cranking cycle stops; fault lamp lights | Fuel supply | Check fuel supply |
| 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 | |
| Overcrank fault lamp lights and engine stops cranking after approximately 75 seconds | See engine service manual for troubleshooting fuel system; After correcting fault, reset engine monitor relay by placing Run-Stop/Reset-Remote switch to Stop/Reset position, depressing Reset button, then to the required running position | |
| Engine runs, shuts down, cranks for 75 seconds, cranking cycle stops, overcrank light ON | Fuel supply | Check fuel supply |
| Low oil pressure shutdown | Oil level | Check oil level; replenish if necessary |
| Low oil pressure shutdown | Sensor (faulty sensor will shut down engine) | Check sensor |
| Low oil pressure shutdown | Oil system fault | Refer to engine service manual for troubleshooting guide for oil system |
| High engine temperature shutdown | Coolant level | Check coolant level; replenish if necessary |
| High engine temperature shutdown | City water cooled sets — water flow, valves, etc. | Check water flow, valves, etc. |
| High engine temperature shutdown | Sensor or thermostat | Check sensor; check thermostat |
| High engine temperature shutdown | Radiator model — fan belts, radiator obstructions, etc. | Check fan belts, radiator for obstructions, etc. |
| Overspeed shutdown | Governor and throttle linkages not free to move; overspeed switch | Check governor and throttle linkages for freedom of movement; Check overspeed switch |
| Overspeed light on, no shutdown | Disconnect wire at TB11-29; Light on after reset; replace engine monitor board | |
| Low oil pressure light ON. No shutdown | Disconnect wire at TB11-30; Light ON after relay reset; Replace engine monitor board | |
| High engine temperature light ON. No shutdown | Disconnect wire at TB11-31; Light ON after relay reset; Replace engine monitor board |
Fault codes and symptom→remedy steps extracted from this model’s service/owner documentation; verify against the official manual before servicing.
Documented causes: Oil level (engine will shut down if sensor is closed); Oil system fault; High engine temperature; Faulty oil pressure sensor or faulty high engine temperature sensor. See the table for the matching fixes.
Documented causes: Coolant level; City water cooled sets — water flow, valves, etc.; Sensor or thermostat; Radiator model — fan belts, radiator obstructions, etc.. See the table for the matching fixes.
Documented causes: Oil level; Sensor (faulty sensor will shut down engine); Oil system fault. See the table for the matching fixes.