68-BLEND DOOR DRIVER CIRCUIT SHORTED TO IGNITION (MTC)

For a complete wiring diagram Refer to Section 8W.

Theory of Operation

NOTE: This DTC will display as active if the ignition is not cycled after running the Actuator Circuit Test / Door Calibration Function. Otherwise, it will display as stored until cleared.

By running the Actuator Circuit Test / Door Calibration Function, the A/C Heater Control can identify up to three door driver circuits shorted simultaneously. A DTC 72 will set if more than three door driver circuits are shorted in the same direction (e.g. four door driver circuits all shorted to ground) or if two or more door driver circuits are shorted with at least one door driver circuit shorted to ignition and one door driver circuit shorted to ground. To ensure a proper diagnosis, diagnose and repair Actuator Circuit Test faults in the following order: If present, diagnose and repair DTC 72 first, then DTC 62, then DTC 61, then DTCs 64, 66, 68, or 71, and finally DTCs 63, 65, 67, or 69. In addition, always test the door driver circuits after each repair by clearing DTCs, and then running the Actuator Circuit Test / Door Calibration Function, and then checking for DTCs.

When Monitored:
When running the Actuator Circuit Test / Door Calibration Function.
Set Condition:
If the A/C Heater Control detects a short to voltage on the (C255) Left Blend Door Driver circuit.

Possible Causes

(C255) LEFT BLEND DOOR DRIVER CIRCUIT SHORTED TO VOLTAGE

A/C HEATER CONTROL

Diagnostic Test

1. CHECK THE (C255) LEFT BLEND DOOR DRIVER CIRCUIT FOR A SHORT TO VOLTAGE

Turn the ignition off.
Disconnect the A/C Heater Control C2 harness connector.
Turn the ignition on.
Measure the voltage of the (C255) Left Blend Door Driver circuit.

Is the voltage above 0.2 volts?

Yes

Repair the (C255) Left Blend Door Driver circuit for a short to voltage.

Perform BODY VERIFICATION TEST – VER 1. (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES - STANDARD PROCEDURE).

Go To 2

2. VERIFY THAT THE FAULT IS STILL PRESENT

Turn the ignition off.
Reconnect the A/C Heater Control C2 harness connector.
Turn the ignition on.
Actuate the Clear DTC function by performing the following:

Turn the blower control on.
Press the A/C mode switch down, turn the blower control to off, wait until both LEDs illuminate (approximately 5 seconds) and then release the A/C mode switch.
When the A/C status indicator begins displaying DTCs, set the Mode switch to the floor position, simultaneously press the A/C mode switch and the EBL mode switch down until both LEDs start flashing (approximately 5 seconds) and then release the mode switches. Stored DTCs will clear from memory in approximately two seconds.

Turn the ignition off, wait 10 seconds, and turn the ignition on.
Actuate the Actuator Circuit Test / Door Calibration Function by performing the following:

Turn the blower control off.
Press and hold the EBL mode switch down and then turn the blower control on. Continue to hold the EBL mode switch down until the EBL status indicator begins flashing. Then, release the EBL mode switch. While the test / function is running, the EBL status indicator will flash once per second. If the test / function passes, the EBL status indicator will stop flashing. If the test / function fails, the A/C and EBL status indicators will flash alternately. Allow the test / function to run to completion before proceeding.

Actuate the Display DTC function by performing the following:

Turn the blower control on.
Press the A/C mode switch down, turn the blower control to off, wait until both LEDs illuminate (approximately 5 seconds) and then release the A/C mode switch.

NOTE: The A/C status indicator displays active DTCs when the EBL status indicator is not illuminated and stored DTCs when the EBL status indicator is illuminated.

Read DTCs from the A/C status indicator.

Does the A/C status indicator display DTC 68?

Yes

Replace the A/C Heater Control in accordance with the Service Information.

Perform BODY VERIFICATION TEST – VER 1. (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES - STANDARD PROCEDURE).

Using the wiring diagram as a guide, inspect the wiring and connectors for conditions causing an intermittent short that set the original fault. Repair as necessary. Then, if present, diagnose and repair all other DTCs. Refer to the Table of Contents in this Section for a complete list of HVAC related symptoms.
Perform BODY VERIFICATION TEST – VER 1. (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES - STANDARD PROCEDURE).