Onan
No AC Output / Loss of Excitation
Generator runs but does not produce AC power at the terminals
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Safety Warning
This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.
If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.
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Possible Causes
Failed voltage regulator, Loss of residual magnetism in alternator, Open stator or rotor winding, Loose main output connections
How to Fix / Troubleshooting
Safety first: High voltage may appear unexpectedly. Open the main breaker, disable auto-start, and use a properly rated meter.
- Verify breaker position: Ensure the generator main breaker is in the ON position. Some models have multiple breakers.
- Measure voltage at lugs: With the unit running, carefully measure voltage at the generator output lugs. If zero, suspect excitation or alternator issues.
- Inspect regulator and wiring: Check the voltage regulator connections and harness for damage. Reseat connectors.
- Residual magnetism: Some alternators may need field flashing to restore magnetism; this should be done only by a qualified technician following Onan procedures.
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Repair Difficulty
Professional Required
5/5
Required Part
Voltage Regulator
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