DTC Troubleshooting: B1239 (M)

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

1.Clear the DTC with the HDS.

2.Turn the ignition switch OFF, and then ON (II).

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

4.Check for DTCs.

Is DTC B1239 or M indicated?


YES - Go to 5.


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


5.Turn the ignition switch OFF.

6.Test the mode control motor.

Is the mode control motor OK?


YES - Go to 7.


NO - Replace the mode control motor.n


7.Disconnect the mode control motor 7P connector.

8.Disconnect the climate control unit 32P connector.

9.Check for continuity between the following terminals of the climate control unit 32P connector and the mode control motor 7P connector.

32P: 7P: 
No. 10 No. 1 
No. 12 No. 2 
No. 19 No. 7 
No. 20 No. 3 
No. 21 No. 4 
No. 22 No. 5 
No. 23 No. 6 

 

Is there continuity?


YES - Go to 10.


NO - Repair any open in the wires between the climate control unit and the mode control motor.n

10.Check for continuity between body ground and the climate control unit 32P connector terminals No. 10, 12, 19, 20, 21, 22, and 23 individually.

 

Is there continuity?


YES - Repair any short to body ground in the wires between the climate control unit and the mode control motor.n


NO - Go to 11.


11.Check for continuity between the climate control unit 32P connector terminals as follows.

From terminal To terminals 
10 12, 19, 20, 21, 22, 23 
12 19, 20, 21, 22, 23 
19 20, 21, 22, 23 
20 21, 22, 23 
21 22, 23 
22 23 

Is there continuity between any of the terminals?


YES - Repair the short in the wires.n


NO - Go to 12.

12.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 wires 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.n


NO - Check for loose wires or poor connections at the climate control unit 32P 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.n