G and AUTO

DTC Troubleshooting: B1231 or Indicator G and AUTO

DTC B1231 or DTC indicator G and AUTO: An Open in the 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 evaporator temperature sensor circuit.


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

6. Disconnect climate control unit connectors A (28P) and B (12P).

7. Check for continuity between climate control unit connector A (28P) terminal No. 23 and evaporator temperature sensor 2P connector terminal No. 2.

Is there continuity?
YES - Go to step 8.

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






8. Check for continuity between climate control unit connector B (12P) terminal No. 10 and evaporator temperature sensor 2P connector terminal No. 1.

Is there continuity?
YES - Go to step 9.

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






9. Remove the evaporator temperature sensor, Service and Repair and test it. Evaporator Temperature Sensor Test

Is the evaporator temperature sensor OK?
YES - Check for loose wires or poor connections at climate control unit connectors A (28P), B (12P), and at the 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 - Replace the evaporator temperature sensor.