Cummins/Onan — Armature Ground Test
Testing & diagnosis · Armature AC winding / collector rings
From a Cummins/Onan service manual — check it applies to your exact model before use.
Applies to: Cummins/Onan MCCK
Procedure
- Lift the brushes before conducting these tests.
- Place one test prod on one of the collector rings and the other on the armature shaft.
- The tester buzzer should not buzz (lamp should not light).
- If it buzzes or lights, the AC winding or a collector ring is grounded to the shaft.
- Test each collector ring in this manner.
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Full service-parts list: Cummins/Onan MCCK →
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.