G and AUTO

DTC Troubleshooting: B1231 (G and AUTO)

DTC B1231 or DTC indicator G and AUTO:

An Open in the Evaporator Temperature Sensor Circuit

1. Clear the DTC by turning the ignition switch to LOCK (0), and then turn to ON (II).

2. Operate the climate control system in several modes.

3. Check for DTCs using the HDS How to Troubleshoot the Climate Control System or self-diagnostic function How to Troubleshoot the Climate Control System.

Is DTC B1231 or G and AUTO indicated?

YES -

Go to step 4.

NO -

Intermittent failure, check for loose wires or poor connections on the evaporator temperature sensor circuit.�

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

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

Does the evaporator temperature sensor test OK?

YES -

Go to step 6.

NO -

Replace the evaporator temperature sensor.�

6. Disconnect the front climate control unit 30P connector.

7. Check for continuity between front climate control unit 30P connector terminal No. 21 and evaporator temperature sensor 2P connector terminal No. 1.





Is there continuity?

YES -

Go to step 8.

NO -

Repair an open in the wire between the front climate control unit and the evaporator temperature sensor.�

8. Check for continuity between front climate control unit 30P connector terminal No. 29 and evaporator temperature sensor 2P connector terminal No. 2.





Is there continuity?

YES -

Check for loose wire or poor connections at the front climate control unit 30P connector and at the evaporator temperature sensor 2P connector. If the connections are good, substitute a known-good front climate control unit, and recheck. If the symptom/indication goes away, replace the original front climate control unit Front Climate Control Unit Removal/Installation.�

NO -

Repair an open in the wire between the front climate control unit and the evaporator temperature sensor.�