Yamaha Auto Start Signal / ATS Control Failure

Generator fails to start automatically during a utility outage, but starts normally in MANUAL mode.

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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

Open auto-start control wiring from ATS, Incorrect ATS control settings, Faulty ATS start relay, Generator controller not in AUTO mode

How to Fix / Troubleshooting

Safety first: Ensure the transfer switch is in a safe position and that backfeed to the utility cannot occur.

  • Verify controller mode: Confirm the Yamaha generator controller is set to AUTO, not OFF or MANUAL.
  • Simulate outage: Follow Yamaha/ATS instructions to simulate a utility failure and observe whether the start signal is sent.
  • Check control wiring: Inspect the two-wire or multi-wire start control cable between the ATS and generator for continuity and correct landing on terminals.
  • Test ATS start relay: In the ATS, test the start relay coil and contacts. Replace the relay if it does not energize during an outage simulation.
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Repair Difficulty

Medium 3/5

Required Part

ATS Start Control Relay
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