Cummins/Onan — Troubleshoot - No AC Output Voltage
Testing & diagnosis · Generator / voltage regulator
From a Cummins/Onan service manual — check it applies to your exact model before use.
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Procedure
- Check load breaker closed
- Check for broken or loose wires
- Check voltage regulator plugs fully seated
- Check field resistance
- Excite genset with external battery source and check for AC output
- Check main and quad winding resistance
- Check main rotor and exciter rotor resistance
- Check rotating diode assemblies
Specs & values
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.