DTC Troubleshooting: 4

DTC indicator 4:  An Open or Short in the Mode Control Motor Circuit

1.Clear the DTC.

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

3.Do the self-diagnostic with the HVAC control unit .

4.Check for DTCs.

Is DTC 4 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 HVAC control unit 24P connector.

9.Check for continuity between the following terminals of the HVAC control unit 24P connector and the mode control motor 7P connector.

24P: 7P: 
No. 3 No. 6 
No. 4 No. 5 
No. 5 No. 4 
No. 6 No. 3 
No. 13 No. 7 
No. 14 No. 1 
No. 15 No. 2 

 

Is there continuity?


YES - Go to 10.


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

10.Check for continuity between body ground and the HVAC control unit 24P connector terminals No. 3, 4, 5, 6, 13, 14, and 15 individually.

 

Is there continuity?


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


NO - Go to 11.


11.Check for continuity between the HVAC control unit 24P connector terminals as follows.

From terminal To terminals 
4, 5, 6, 13, 14, 15 
5, 6, 13, 14, 15 
6, 13, 14, 15 
13, 14, 15 
13 14, 15 
14 15 

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 HVAC control unit and the mode control motor. This short may also damage the HVAC control unit. Repair the short to power before replacing the  HVAC control unit.n


NO - Check for loose wires or poor connections at the HVAC control unit 24P connector and at the mode control motor 7P connector. If the connections are good, substitute a known-good HVAC control unit, and recheck. If the symptom/indication goes away, replace the original  HVAC control unit.n