DTC Troubleshooting: B1233 (A and A/C ON)
DTC B1233 or DTC indicator A and A/C ON:
An Open 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 B1233 or A and A/C ON indicated?
YES -
Go to Step 5 .
NO -
Intermittent failure; check for loose wires or poor connections on the driver's air mix control motor circuit.■
  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 7 .
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 the following terminals of heater control unit connectors A (28P), B (12P), and the driver's air mix control motor 7P connector.
    28P:
    7P:
    No. 14
    No. 3
    No. 10
    No. 7
    No. 12
    No. 5
    No. 10
    No. 5
    No. 12
    No. 7



Is there continuity?
YES -
Check for loose wires or poor connections at heater control unit connectors A (28P), B (12P), and at the driver's air mix control motor 7P connector. If the connections are good, substitute a known-good heater control unit and recheck. If the symptom/indication goes away, replace the original heater control unit .■
NO -
Repair open in the wire(s) between the heater control unit and the driver's air mix control motor.■