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 with the HDS.
  1. Turn the ignition switch to LOCK (0) and then to ON (II).
  1. Do the self-diagnostic function with the HDS or the climate control unit.
  1. 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.■
  1. Turn the ignition switch to LOCK (0).
  1. Disconnect climate control unit connectors A (28P) and B (12P).
  1. Check for continuity between climate control unit connector A (28P) No. 23 terminal and the evaporator temperature sensor 2P connector No. 2 terminal.
Is there continuity?
YES -
Go to Step 8 .
NO -
Repair open in the wire between the climate control unit and the evaporator temperature sensor.■