Cummins/Onan — Overcrank Test
Testing & diagnosis · Generator set overcrank relay
From a Cummins/Onan service manual — check it applies to your exact model before use.
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Before you start
- Take precautions against accidental starting of the generator set including disconnecting the battery cables.
Procedure
- Disconnect the positive lead from the starter.
- Insulate lead so it cannot touch metal frame.
- Move the operation selector switch on the engine control to REMOTE.
- Move the Test/Normal/Retransfer switch to TEST. Fault or overcrank lamp should light at end of crank period.
- Move the Test/Normal/Retransfer switch to NORMAL.
- Move the generator set operation selector switch to STOP.
- Reconnect positive lead to starter.
- Move the generator set operation selector switch to REMOTE.
Specs & values
- Crank period usually factory set at 75, +15 seconds
Source: Cummins/Onan service manual. Steps and values are as documented; always cross-check against the official manual and any later revisions for your exact serial number before servicing.