Electronic Climate Control

DTC B1239 or DTC indicator O: An Open or Short in the Mode Control Motor Circuit

1. Clear the DTC with the HDS.
2. Operate the climate control system in several modes.
3. Check for DTCs using the HDS or self-diagnostic.

Is DTC B1239 or O indicated?

YES - Go to step 4.

NO - Intermittent failure, check for loose wires or poor connections on the mode control motor circuit.

4. Turn the ignition switch OFF.
5. Test the mode control motor.

Is the mode control motor OK?

YES - Go to step 6.

NO - Replace the mode control motor.

6. Disconnect the mode control motor 7P connector.
7. Disconnect the climate control unit 30P connector.




8. Check for continuity between the above terminals of climate control unit 30P connector and the mode control motor 7P connector.

Is there continuity?

YES - Go to step 9.

NO - Repair any open in the wire(s) between the climate control unit and the mode control motor.




9. Check for continuity between body ground and the climate control unit 30P connector terminals No. 2, 3, 4, 18, 19, and 22 individually.

Is there continuity?

YES - Repair any short to body ground in the wire(s) between the climate control unit and the mode control motor.

NO - Go to step 10.




10. Check for continuity between the climate control unit 30P connector terminals as above.

Is there continuity between any of the terminals?

YES - Repair the short in the wires.

NO - Go to step 11.




11. Turn the ignition switch ON (II), and check the same terminals for voltage to body ground.

Is there any voltage?

YES - Repair any short to power in the wire(s) between the climate control unit and the mode control motor. This short may also damage the climate control unit. Repair the short to power before replacing the climate control unit

NO - Check for loose wires or poor connections at the climate control unit 30P connector and at the mode control motor 7P 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.