Cummins/Onan — Armature Test
Testing & diagnosis
From a Cummins/Onan service manual — check it applies to your exact model before use.
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Procedure
- Test for ground by placing one test prod of continuity type test lamp on center shaft and other prod first on commutator, then on one collector ring.
- If lamp lights, armature grounded.
- Place test prod on each of two collector rings. If lamp does not light, AC winding has open circuit.
- Use armature growler to test DC winding for open circuit and short circuit.
- Follow growler manufacturer directions.
Tools required
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.