DTC Troubleshooting: B1231 (G and AUTO)
  1. Check for continuity between climate control unit connector B (12P) No. 10 terminal and the evaporator temperature sensor 2P connector No. 1 terminal.
Is there continuity?
YES -
Go to Step 9 .
NO -
Repair open in the wire between the climate control unit and the evaporator temperature sensor.■
  1. Remove the evaporator temperature sensor, and test it.
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 .■