Without Climate Control

DTC Troubleshooting: B1239 (4)

DTC B1239 or DTC indicator 4:

An Open or Short in the Mode Control Motor Circuit

1. Clear the DTC with the HDS.

2. Operate the heater-A/C control system in several modes.

3. Check for DTCs using the HDS or the self-diagnostic function.

Is DTC B1239 or 4 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 to LOCK (0).

5. Test the mode control motor Mode Control Motor Test.

Is the mode control motor OK?

YES -

Go to step 6.

NO -

Replace the mode control motor Mode Control Motor Replacement.�

6. Disconnect the mode control motor 7P connector.

7. Disconnect the HVAC control unit 30P connector.

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









Is there continuity?

YES -

Go to step 9.

NO -

Repair an open in the wire(s) between the HVAC control unit and the mode control motor.�

9. Check for continuity between body ground and HVAC control unit 30P connector terminals No. 27, 28, 29, and 30 individually.





Is there continuity?

YES -

Repair a short to body ground in the wire(s) between the HVAC control unit and the mode control motor.�

NO -

Go to step 10.

10. Check for continuity between HVAC control unit connector terminals as follows.





Is there continuity between any of the terminals?

YES -

Repair the short in the wire(s).�

NO -

Go to step 11.

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





Is there any voltage?

YES -

Repair a short to power in the wire(s) 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.�

NO -

Check for loose wires or poor connections at the HVAC control unit 30P connector and the mode control motor 7P connector. If the connections are good, substitute a known-good HVAC control unit HVAC Control Unit Removal/Installation (Without Climate Control), and recheck. If the symptom/indication goes away, replace the original HVAC control unit HVAC Control Unit Removal/Installation (Without Climate Control).�