Cummins/Onan 4.0 BF-1R/9500 — Armature Ground and Open Tests
Testing & diagnosis · AC generator armature
For the Cummins/Onan 4.0 BF-1R/9500, from the Cummins/Onan service manual.
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Procedure
- Use a 120 volt series test lamp set; armature must be removed from generator
- Place one test prod on one collector ring and the other on the armature shaft
- Test lamp should not light; if it lights, winding or collector ring is grounded to shaft
- Test both collector rings
- For open test, place one prod on each collector ring; lamp should light; if not, armature is open
Tools required
- 120 volt series test lamp set Amazon
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
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.