Heating/Air Conditioning

DTC 4: A Problem in the Evaporator Temperature Sensor Circuit

1. Disconnect the evaporator temperature sensor 2P connector.
2. Measure the resistance between the No. 1 and No. 2 terminals of the evaporator temperature sensor.






Is the resistance within the specifications shown on the graph?

YES - Go to step 3.

NO - Replace the evaporator temperature sensor.

3. Disconnect the HVAC control unit 30P connector.
4. Check for continuity between the No. 7 terminal of the HVAC control unit 30P connector and body ground.






Is there continuity?

YES - Repair short to body ground in the wire between the HVAC control unit and the evaporator temperature sensor.

NO - Go to step 5.

5. Check for continuity between the No. 7 terminal of the HVAC control unit 30P connector and the No. 2 terminal of the evaporator temperature sensor 2P connector.






Is there continuity?

YES - Go to step 6.

NO - Repair open in the wire between the HVAC control unit and the evaporator temperature sensor.

6. Check for continuity between the No. 10 terminal of the HVAC control unit 30P connector and the No. 1 terminal of the evaporator temperature sensor 2P connector.






Is there continuity?

YES - Check for loose wires or poor connections at the HVAC control unit 30P connector and at the evaporator temperature sensor 2P connector. If the connections are good, substitute a known-good HVAC control unit, and recheck. If the symptom/indication goes away, replace the original HVAC control unit.

NO - Repair open in the wire between the HVAC control unit and the evaporator temperature sensor.