Guardian No Automatic Start on Power Failure

Generator fails to automatically start when utility power is lost, but will start manually from the controller.

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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

Controller not in AUTO mode, Faulty utility sensing circuit, Open control wiring between ATS and generator, Misconfigured start delay settings

How to Fix / Troubleshooting

Safety first: Simulate outages only when it is safe to interrupt power. Inform occupants before testing.

  • Verify AUTO mode: Ensure the Guardian controller switch is set to AUTO.
  • Check utility sense fuses: Inspect any low-voltage fuses or breakers feeding the utility sensing circuit.
  • Inspect control wiring: Check the multi-conductor control cable between the generator and transfer switch for continuity and secure terminations.
  • Review settings: Confirm start delay and sensing parameters in the controller are set per Guardian specifications.
  • Professional diagnosis: If the unit still will not auto-start, the ATS control board or generator controller may require replacement.
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Repair Difficulty

Medium 3/5

Required Part

Utility Sensing Circuit (Transfer Switch Board)
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