Cummins/Onan — Armature Grounded Test
Testing & diagnosis
From a Cummins/Onan owner's manual covering: 1.5UF-232S, 10.0UF-150S, 12.0UF-3S, 12.0UF-4S, 15.0UB-150S, 15.0UF-3S/104, 2.0UF-125S, 2.0UF-232S/32, 2.0UG-1S/135, 2.5UF-1S, 2.SUD-IS, 2.SUD-IS/ID…. Check it applies to your exact model before use.
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Procedure
- Lift all brushes out of their holders.
- Use a continuity type test lamp set.
- Place one prod on the commutator and the other on a bare clean frame or armature shaft part.
- The lamp should not light; if it lights, the armature is grounded.
- Test the slip rings the same way; replace with a new armature if grounded.
Tools required
- continuity test lamp set Amazon
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Source: Cummins/Onan owner's 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.