Coolant Temperature Sensor / Switch HVAC: Testing and Inspection
ECT Sensor Circuit Troubleshooting1. Check the malfunction indicator lamp (MIL).
Does the malfunction indicator lamp come on?
YES - Read the DTC and perform the appropriate troubleshooting for that code. Refer to the fuel and emissions section.
NO - Go to step 2.
2. Turn the ignition switch OFF.
3. Disconnect the ECT sensor 2P connector.
4. Disconnect the climate control unit 8P connector.
5. Turn the ignition switch ON (II).
6. Measure the voltage between the No.3 terminal of the climate control unit 8P connector and body ground.
Is there about 5 volts?
YES - Check for loose wires or poor connections at the climate control unit 8P connector and at the ECT sensor 2P connector. If the connections are good, substitute a known-good climate control unit, and recheck. If the symptom/indication goes away, replace the original climate control unit.
NO - Repair open in the wire between the climate control unit and the ECT sensor.