Onan

LOP

UnclassifiedCooling

What This Code Means

Engine malfunction shutdown; Common fault lamp is illuminated and none of the diagnostic diodes (overcrank, low oil pressure, high engine temperature) are illuminated; Engine does not start within 75 seconds during cycle cranking; Engine monitor lights fault lamp and opens the cranking circuit; High engine temperature warning/shutdown; Low oil pressure warning/shutdown; Low engine temperature fault lamp illuminated (no associated engine shutdown); Low oil pressure; Engine malfunction shutdown immediately after start; Overspeed light on; Engine overspeed during operation; Engine stops running after about 12 seconds; LOP lamp comes on; Engine stops running after about 1 minute; OC (overcrank) lamp comes on; Engine shutdown; Engine fails to start; Overspeed; High engine temperature; Low engine temperature; Fault light illuminated; Engine shuts down after running short time; LOP lamp comes on and engine stops running after about 12 seconds; OC (overcrank) lamp comes on and engine stops aft

Possible Causes

  • •Defective Engine Monitor module J5
  • •Defective Start-Disconnect module J3
  • •Defective oil pressure sensor
  • •Engine malfunction
  • •Engine not pumping oil properly
  • •Engine temperature reaches 215°F (102°C)
  • •Failure to build up oil pressure within approximately 12 seconds
  • •Failure to start within a 75-second cranking period
  • •Fault in Fno+ Overspeed module
  • •Fault in Overspeed module
  • •Fault in Shutdown module
  • •Low engine temperature
  • •Low oil pressure
  • •Oil pressure reaches 97 kPa
  • •Overcrank (failure to start)
  • •Overspeed condition (approximately 2100 r/min)
  • •Remote governor control set at High RPM position
  • •Start-Disconnect does not operate after engine starts
  • •Stuck or restricted governor linkage
  • •Stuck or restricted throttle linkage
  • •Throttle & governor linkage restricted movement

Suggested Actions

  1. 1Check for B+ at K13 terminal 3 to verify Start-Disconnect operation
  2. 2Check for B+ voltage at K13 terminal 3
  3. 3Check or replace Engine Monitor module J5
  4. 4Check or replace Overspeed module
  5. 5Check or replace Shutdown module
  6. 6Check or replace Start-Disconnect module J3
  7. 7Check throttle & governor linkage for free movement
  8. 8Check throttle and governor linkage for free movement
  9. 9Disconnect module J3 to check if engine runs OK
  10. 10Ensure remote governor control is not set at 'High RPM' position
  11. 11Ensure remote governor control is not set at High RPM position
  12. 12Have control panel interior components adjusted, tested, or replaced by a qualified service representative
  13. 13Inspect or replace Overspeed module
  14. 14Inspect or replace Shutdown module
  15. 15Manually reset the engine monitor using the Reset Switch after an engine shutdown
  16. 16Reconnect wire
  17. 17Refer to the one-light troubleshooting guide for fault location
  18. 18Remove wire from terminal TB11-30 (P1-6 to S1) and reset
  19. 19Remove wire from terminal TB11-30 (PI-6 to SI) and reset
  20. 20Use the manual reset switch for the engine monitor after an engine shutdown

Related Onan Fault Codes

LOW ENGINE TEMPERATURELOW OIL PRESSURELETLOW OIL PRESSURE LAMPHIGH ENGINE TEMPERATURE LAMPO.C.HIGH ENGINE TEMPERATUREO.S.HETOVERCRANKFAULT CODE 4OVERCRANK LAMP
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