DTC Troubleshooting: B1231 (G and AUTO)
DTC B1231 or DTC indicator G and AUTO:
An Open in the Front Evaporator Temperature Sensor Circuit
1. Clear the DTCs with the HDS.
2. Turn the ignition switch to LOCK (0) and then back to ON (II).
3. Do the self-diagnostic function with the HDS or the climate control unit.
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 in the front evaporator temperature sensor circuit.?
5. Turn the ignition switch to LOCK (0).
6. Remove the front evaporator temperature sensor See: Heating and Air Conditioning/Evaporator Temperature Sensor / Switch/Service and
Repair/Front Evaporator Temperature Sensor Replacement, and test it See: Heating and Air Conditioning/Evaporator Temperature Sensor /
Switch/Testing and Inspection.
Is the front evaporator temperature sensor OK?
YES -
With the front evaporator temperature sensor disconnected, go to step 7.
NO -
Replace the front evaporator temperature sensor See: Heating and Air Conditioning/Evaporator Temperature Sensor / Switch/Service and
Repair/Front Evaporator Temperature Sensor Replacement.?
7. Disconnect climate control unit connector A (40P).
8. Check for continuity between climate control unit connector A (40P) terminal No. 24 and front evaporator temperature sensor 2P connector
terminal No. 2.
Is there continuity?
YES -
Go to step 9.
NO -
Repair an 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 front evaporator temperature sensor 2P connector
