G and Auto

DTC Troubleshooting: B1231 or Indicator G and AUTO

DTC B1231 or DTC indicator G and AUTO:An Open in the Front Evaporator Temperature Sensor Circuit

1. Clear the DTC with the HDS.

2. Turn the ignition switch to LOCK (0), and then to ON (II).

3. Do the self-diagnostic function with the HDS Initial Inspection and Diagnostic Overview or climate control unit. Initial Inspection and Diagnostic Overview

4. Check for DTCs.

Is DTC B1231 or G and AUTO indicated?
YES - Go to step 5.

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


5. Turn the ignition switch to LOCK (0).

6. Remove the front evaporator temperature sensor, Front Evaporator Temperature Sensor Replacement and test it. Testing and Inspection

Is the front evaporator temperature sensor OK?
YES - Go to step 7.

NO - Replace the front evaporator temperature sensor.


7. Disconnect climate control unit connector A (40P).

8. Check for continuity between climate control unit connector A (40P) terminal No. 24 and the front evaporator temperature sensor 2P connector terminal No. 2.

Is there continuity?
YES - Go to step 9.

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






9. Check for continuity between climate control unit connector A (40P) terminal No. 8 and the front evaporator temperature sensor 2P connector terminal No. 1.

Is there continuity?
YES - Check for loose wires or poor connections at climate control unit connector A (40P) and at the front evaporator temperature 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 front evaporator temperature sensor.