( TL19E00K733000Y1235FAAT00 )

DTC Troubleshooting: B1235 (C and A/C ON)

DTC B1235 or DTC indicator C and A/C ON:
A Problem in the Driver's Air Mix Control Linkage, Door, or 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 B1235 or C 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, or repair the driver's air mix control linkage or door.■

1. Disconnect the driver's air mix control motor 7P connector.

1. Disconnect heater control unit connector A (28P).

1. Check for continuity between the following terminals of heater control unit connector A (28P) and the driver's air mix control motor 7P connector.

   LHD model
   28P: | 7P:
   --- | ---
   No. 4 | No. 2
   No. 6 | No. 1
   No. 4 | No. 1
   No. 6 | No. 2

Is there continuity?

YES | - | Go to Step 10 .
NO | - | Repair open in the wire(s) between the heater control unit and the driver's air mix control motor.■

1. Check for continuity between body ground and heater control unit connector A (28P) No. 4 and No. 6 terminals individually.

Is there continuity?

YES | - | Repair short to body ground in the wire(s) between the heater control unit and the driver's air mix control motor.■
NO | - | Substitute a known-good heater control unit, and recheck. If the symptom/indication goes away, replace the original heater control unit .■