Cummins/Onan — Troubleshoot - High/Low AC Output

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

1. Check proper output lead connection
2. Check genset output voltage
3. Check voltage at line side of genset breaker
4. Check voltage at load side of genset breaker
5. Check sense leads condition and fully seated in connector to voltage regulator
6. Check field, main, and quad winding resistance
7. Check main rotor and exciter rotor resistance
8. Check rotating diode assemblies

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.

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