Cummins/Onan — Field Winding Inspection
Testing & diagnosis · Alternator field winding
From a Cummins/Onan service manual — check it applies to your exact model before use.
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Procedure
- Remove brushes and measure resistance between slip rings.
- If specified resistance is obtained at slip rings but not at brush terminals, clean or replace brushes.
- If specified resistance is not obtained at slip rings, clean or replace rotor.
Tools required
- ohmmeter Amazon
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- 2400: 40-50 Ω
- 3500: 35-45 Amazon Ω
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.