E17
CTC
ECM Communication Fault
Furnace indicates communication error between main control board and ECM blower module.
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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
Loose ECM harness connector, Damaged ECM communication cable, Failed ECM module on blower, Faulty CTC main control board
How to Fix / Troubleshooting
Safety first: Disconnect power before unplugging any ECM or control connectors.
Steps:
- Locate the ECM blower motor and its multi-pin communication connector.
- Unplug and inspect the ECM harness for bent pins, corrosion, or damage. Reseat firmly.
- Trace the harness back to the CTC ECM-compatible control board and ensure all connectors are fully seated.
- Restore power and call for fan operation (fan ON at thermostat). If the error persists, either the ECM module or the control board may be defective.
- Because ECM diagnostics require specialized tools, have a technician test and replace the ECM motor or control board as needed.
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Repair Difficulty
Professional Required
5/5
Required Part
CTC ECM Blower Motor Module
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