Manufacturer Code Charts: 5

DTC Troubleshooting: B1240 or Indicator 5

DTC B1240 or DTC indicator 5: A Problem in the Mode Control Linkage, Doors, or Motor

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 B1240 or 5 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 or repair the mode control linkage or doors.


6. Disconnect the mode control motor 7P connector.

7. Disconnect HVAC control unit 30P connector.

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





Is there continuity?
YES - Go to step 9.

NO - Repair 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. 16 and No. 17 individually.

Is there continuity?
YES - Repair short to body ground in the wire(s) between the HVAC control unit and the mode control motor.

NO - 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.