Kohler-SDMO Unintended Start / Control Logic Fault

Generator starts unexpectedly or attempts to start with mains power present

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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

Incorrect mains sensing thresholds, Stuck ATS auxiliary contact, Faulty start input wiring (remote start), Misconfigured APM controller

How to Fix / Troubleshooting

Safety first: Immediately set the controller to OFF and apply lockout/tagout to prevent automatic starts. This is a serious safety issue.

  • Check remote start inputs: Inspect any external start/stop contacts or BMS interfaces for stuck or shorted signals.
  • Verify mains sensing: Confirm that mains voltage and frequency are correctly sensed and within configured limits.
  • ATS feedback: Test ATS auxiliary contacts for correct operation; replace if welded or stuck.
  • Controller configuration: Review APM settings for start/stop logic, including 2-wire/3-wire remote start modes, and correct as per installation design.

Because unintended starts are hazardous, have a qualified technician verify the entire control chain before returning to AUTO mode.

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Repair Difficulty

Professional Required 5/5

Required Part

APM Controller Input Wiring
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