B1234

DTC Troubleshooting: B1234 (K and AUTO)

DTC B1234 or DTC indicator K and AUTO:

A Short in the Driver's Air Mix Control Motor Circuit

1. Clear the DTCs with the HDS.

2. Turn the ignition switch to LOCK (0) and then back to ON (II).

3. Do the self-diagnostic function with the HDS or the climate control unit.

4. Check for DTCs.

Is DTC B1234 or K and AUTO indicated?

YES -

Go to step 5.

NO -

Intermittent failure, check for looses wires or poor connections in the driver's air mix control motor circuit.�

5. Check for DTCs.

Are these DTCs also present; B1237 or N and AUTO, and/or B1245 or G, and/or B2968 or A and WINDSHIELD DEFROST, and/or B2980 or B and WINDSHIELD DEFROST?

YES -

Go to step 13.

NO -

Go to step 6.

6. Turn the ignition switch to LOCK (0).

7. Test the driver's air mix control motor Driver's Air Mix Control Motor Test.

Is the driver's air mix control motor OK?

YES -

Go to step 8.

NO -

Replace the driver's air mix control motor Driver's Air Mix Control Motor Replacement.�

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

9. Disconnect climate control unit connector A (40P).

10. Check for continuity between climate control unit connector A (40P) terminal No. 11 and body ground.





Is there continuity?

YES -

Repair a short to body ground in the wire between the climate control unit and the driver's air mix control motor.�

NO -

Go to step 11.

11. Check for continuity between climate control unit connector A (40P) terminals No. 6 and No. 11.





Is there continuity?

YES -

Repair a short in the wires.�

NO -

Go to step 12.

12. Turn the ignition switch to ON (II), and measure the voltage between climate control unit connector A (40P) terminal No. 11 and body ground.





Is there any voltage?

YES -

Repair a short to power in the wire between the climate control unit and the driver's air mix control motor. This short may also damage the climate control unit. Repair a short to power before replacing the climate control unit.�

NO -

Substitute a known-good climate control unit, and recheck. If the symptom/indication goes away, replace the original climate control unit Climate Control Unit Removal/Installation.�

13. Turn the ignition switch to LOCK (0), and disconnect the climate control unit connector A (40P).

14. Disconnect these items:

- Driver's air mix control motor
- Passenger's air mix control motor
- Rear air mix control motor
- Humidity/in-car temperature sensor
- A/C pressure sensor

15. Check for continuity between climate control unit connector A (40P) terminal No. 6 and body ground.





Is there continuity?

YES -

Repair a short to body ground in the wire.�

NO -

Go to step 16.

16. Turn the ignition switch to ON (II), and measure the voltage between the same terminal and body ground.





Is there any voltage?

YES -

Repair a short to power in the wire. This short may have also damaged the climate control unit. Repair a short to power before replacing the climate control unit.�

NO -

Go to step 17.

17. Turn the ignition switch to LOCK (0).

18. Reconnect the climate control unit connector A (40P).

19. Turn the ignition switch to ON (II), and measure the voltage between climate control unit connector A (40P) terminal No. 6 and body ground.





Is there about 5 V?

YES -

Go to step 20.

NO -

Check for a loose wire or poor connection at climate control unit connector A (40P). If the connection is good, substitute a known-good climate control unit, and recheck. If the symptom/indication goes away, replace the original climate control unit Climate Control Unit Removal/Installation.�

20. While measuring the voltage as described in step 19, reconnect these items individually and note the voltage reading each time:

- Driver's air mix control motor
- Passenger's air mix control motor
- Rear air mix control motor
- Humidity/in-car temperature sensor
- A/C pressure sensor





Does the voltage remain at about 5 V?

YES -

Substitute a known-good climate control unit, and recheck. If the symptom/indication goes away, replace the original climate control unit Climate Control Unit Removal/Installation.�

NO -

Replace the component that caused the voltage drop.�