Onan Transfer Switch Fails to Transfer

Automatic transfer switch does not transfer load to generator when it is running

Advertisements

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.

Advertisements

Possible Causes

No transfer signal from generator controller, Faulty transfer switch control board, Mechanical binding of switch mechanism, Incorrect wiring between generator and ATS

How to Fix / Troubleshooting

Safety first: Working on transfer switches involves lethal voltages. Turn off utility power and generator, lock out/tag out, and only proceed if you are qualified.

  • Verify generator output: Confirm the generator is producing correct voltage and frequency at its terminals.
  • Check control signal: Inspect the control wiring between the generator controller and ATS (start/stop and transfer signals). Tighten and reseat connectors.
  • Manual operation: If the ATS has a manual transfer mechanism, test it with power off to ensure it moves freely. Binding indicates mechanical issues.
  • ATS control board: If signals are present but the switch does not operate, the ATS control board or coil may be faulty and require replacement.
Advertisements

Repair Difficulty

Professional Required 5/5

Required Part

Automatic Transfer Switch Control Board
Check Price on Amazon

We may earn a commission from links on this page.

Advertisements