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 - Refer to the fuel and emissions section.
NO - Without Navigation System :Go to step 2
With Navigation System: Go to step 7.
2. Turn the ignition switch OFF.
3. Disconnect the ECT sensor 2P connector.
4. Disconnect climate control unit connector A (8P).
5. Turn the ignition switch ON (II).
6. Measure the voltage between the No.3 terminal of climate control unit connector A (8P) and body ground.
Is there about 5 V?
YES - Check for loose wires or poor connections at climate control unit connector A (8P) 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.
7. Turn the ignition switch OFF.
8. Disconnect the ECT sensor 2P connector.
9. Disconnect climate control unit connector B (26P).
10. Turn the ignition switch ON (II).
11. Measure the voltage between the No.22 terminal of climate control unit connector B (26P) and body ground.
Is there about 5 V?
YES - Check for loose wires or poor connections at climate control unit connector B (26P) 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.