B1231

DTC Troubleshooting: B1231 (TE sensor open)

DTC B1231 or TE sensor open is indicated:

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 back to ON (II).

3. Do the self-diagnostic with the HDS or the climate control unit.

4. Check for DTCs.

Is DTC B1231 or TE sensor open 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. Remove the evaporator temperature sensor Service and Repair and test it Evaporator Temperature Sensor Test.

Is the evaporator temperature sensor OK?

YES -

With the evaporator temperature sensor disconnected, go to step 7.

NO -

Replace the evaporator temperature sensor Service and Repair.�

7. Disconnect the climate control unit 40P connector.

8. Check for continuity between climate control unit 40P connector terminal No. 17 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. Check for continuity between climate control unit 40P connector terminal No. 33 and evaporator temperature sensor 2P connector terminal No. 2.





Is there continuity?

YES -

Check for loose wires or poor connections at the climate control unit 40P connector 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 Climate Control Unit Removal/Installation.�

NO -

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