DTC Troubleshooting: B1234 (B and A/C ON)
DTC B1234 or DTC indicator B and A/C ON:
 A Short in the Driver's Air Mix Control Motor 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 heater control unit.
  1. Check for DTCs.
Is DTC B1234 or B and A/C ON indicated?
YES -
Go to Step 5 .
NO -
Intermittent failure.■
  1. Check for DTCs.
Are these DTCs also present; B121B or H and A/C ON, and/or B1220 or L and A/C ON, and/or B1237 or E and A/C ON?
YES -
Go to Step 13 .
NO -
Go to Step 6 .
  1. Turn the ignition switch to LOCK (0).
  1. Test the driver's air mix control motor.
Is the driver's air mix control motor OK?
YES -
Go to Step 8 .
NO -
Replace the driver's air mix control motor. ■
  1. Disconnect the driver's air mix control motor 7P connector.
  1. Disconnect heater control unit connectors A (28P) and B (12P).
  1. Check for continuity between body ground and heater control unit connector A (28P) No. 14 terminal.
Is there continuity?
YES -
Repair short to body ground in the wire between the heater control unit and the driver's air mix control motor.■
NO -
Go to Step 11 .