B1231

DTC B1231: An Open in the Evaporator Temperature Sensor Circuit

1. Clear the DTC.
2. Turn the ignition switch OFF, and then ON.
3. Operate the climate control system is several modes.
4. Check the DTCs.

Is DTC G or B1231 indicated?

YES - Go to step 5.

NO - Intermittent failure, check for loose wires or poor connections on the evaporator temperature sensor circuit.

5. Remove the evaporator temperature sensor and test it.

Does the evaporator temperature sensor test OK?

YES - Go to step 6.

NO - Replace the evaporator temperature sensor.

6. Disconnect audio-HVAC display panel connector A (22P).




7. Check for continuity between the No.14 terminal of audio-HVAC display panel connector A (22P) and the No.1 terminal of the evaporator temperature sensor 2P connector.

Is there continuity?

YES - Go to step 8.

NO - Repair open in the wire between the audio-HVAC display panel and the evaporator temperature sensor.




8. Check for continuity between the No.15 terminal of audio HVAC display panel connector A (22P) and the No.2 terminal of the evaporator temperature sensor 2P connector.

Is there continuity?

YES - Check for loose wire or poor connections at audio-HVAC display panel connector A (22P) and at the evaporator temperature sensor 2P connector. If the connections are good, substitute a known good audio HVAC display panel, and recheck. If the symptom/indication goes away, replace the original audio HVAC display panel.

NO - Repair open in the wire between the audio HVAC display panel and the evaporator temperature sensor.