Cummins/Onan 2100 Series — Generator/Base Board Isolation Procedure
Testing & diagnosis · Generator and Base board
For the Cummins/Onan 2100 Series, from the Cummins/Onan service manual.
Applies to: Cummins/Onan DGBB, Cummins/Onan DGBC, Cummins/Onan DGCA, Cummins/Onan DGCB, Cummins/Onan DGCG, Cummins/Onan DGDA, Cummins/Onan DGDB, Cummins/Onan DGDK, Cummins/Onan DGFA, Cummins/Onan DGFB, Cummins/Onan DGFC
Before you start
- This test involves unregulated excitation; disconnect all loads.
- HAZARDOUS VOLTAGE.
Procedure
- Throw line circuit breaker OFF and shut down the set.
- Remove control housing side cover; disconnect exciter stator X and XX leads from AC harness.
- Prepare to measure output voltage across generator terminals while set runs.
- Connect a 12V battery jumper positive (+) to X lead (Field +).
- Check polarity again; polarity must be correct.
- Start the set and connect battery negative (-) jumper to XX lead.
- If rated output voltage or higher and all phases balanced, generator is likely OK.
- If unbalanced troubleshoot main stator; if uniformly low troubleshoot exciter and field circuits.
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Normal excitation voltage approximately 10 VDC no-load to 40 VDC full-load
Full service-parts list: Cummins/Onan DGBB →, Cummins/Onan DGBC →, Cummins/Onan DGCA →, Cummins/Onan DGCB →, Cummins/Onan DGDA →, Cummins/Onan DGDB →, Cummins/Onan DGFA →, Cummins/Onan DGFB →, Cummins/Onan DGFC →
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.