Engine - Coolant Temperature Sensor/Switch: Testing and Inspection

ECT Sensor 1 Circuit Troubleshooting

NOTE: Before performing symptom troubleshooting, check for powertrain DTC.

1. Check the malfunction indicator lamp (MIL).

Does the malfunction indicator lamp come on?

YES - Refer to the fuel and emissions systems DTCs.

NO - Go to step 2.

2. Turn the ignition switch OFF.
3. Disconnect the ECT sensor 12P connector.
4. Disconnect climate control unit connector B (30P).
5. Turn the ignition switch ON (II).




6. Measure the voltage between the No. 22 terminal of climate control unit connector B (30P) and body ground.

Is there about 5 V?

YES - Check for loose wires or poor connections at climate control unit connector B (30P) and at the ECT sensor 12P 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 1.