Cummins/Onan 3100 series — Testing Diodes
Testing & diagnosis · Rotating rectifier assembly
For the Cummins/Onan 3100 series, from the Cummins/Onan service manual.
Applies to: Cummins/Onan GGKD
Before you start
- Layers of dust can cause diodes to overheat and fail.
Procedure
- Disconnect the diode pigtails from the terminal posts.
- Measure electrical resistance between each diode pigtail and the plate on which the diode is mounted.
- Reverse the meter test probes and repeat the tests.
- Replace the diode if resistance is high or low in both directions.
Tools required
- Ohmmeter Amazon
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Full service-parts list: Cummins/Onan GGKD →
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.