DTC M

DTC indicator M: A Short in the Heater Core Temperature Sensor Circuit.

1. Disconnect the heater core temperature sensor 2P connector.
2. Test the heater core temperature sensor.

Is the resistance within the specifications shown on the graph?

YES - Go to step 3.

NO - Replace the heater core temperature sensor.

3. Disconnect climate control unit connector B (22P).




4. Check for continuity between the No. 4 terminal of climate control unit connector B (22P) and body ground.

Is there continuity?

YES - Repair short to body ground in the wire between the climate control unit and the heater core temperature sensor.

NO - Substitute a known-good climate control unit, and recheck. If the symptom/indication goes away, replace the original climate control unit.