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Manufacturer Code Charts: 72







72-SHORT TOO COMPLEX (MTC)





For a complete wiring diagram consult Diagrams/Electrical.

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, 68, or 71, and finally DTCs 63, 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 more than three door driver circuits 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 voltage and one door driver circuit shorted to ground.








Diagnostic Test


1. CHECK THE (C266) MODE DOOR DRIVER CIRCUIT, (C66) MODE DOOR COMMON DRIVER CIRCUIT, (C255) LEFT BLEND DOOR DRIVER CIRCUIT, (C55) LEFT BLEND DOOR COMMON DRIVER CIRCUIT, (C268) RECIRCULATION DOOR DRIVER CIRCUIT, & (C68) RECIRCULATION DOOR COMMON 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 (C266) Mode Door Driver circuit, (C66) Mode Door Common Driver circuit, (C255) Left Blend Door Driver circuit, (C55) Left Blend Door Common Driver circuit, (C268) Recirculation Door Driver circuit, and the (C68) Recirculation Door Common Driver circuit.
Is the voltage above 0.2 volts on any of the circuits?

Yes


- Repair all circuits with voltage above 0.2 volts for a short to voltage.
- Perform BODY VERIFICATION TEST - VER 1. Body Verification Test.


No


- Go to 2




2. CHECK THE (C266) MODE DOOR DRIVER CIRCUIT, (C66) MODE DOOR COMMON DRIVER CIRCUIT, (C255) LEFT BLEND DOOR DRIVER CIRCUIT, (C55) LEFT BLEND DOOR COMMON DRIVER CIRCUIT, (C268) RECIRCULATION DOOR DRIVER CIRCUIT, & (C68) RECIRCULATION DOOR COMMON DRIVER CIRCUIT FOR A SHORT TO GROUND




Turn the ignition off.
Measure the resistance of the (C266) Mode Door Driver circuit, (C66) Mode Door Common Driver circuit, (C255) Left Blend Door Driver circuit, (C55) Left Blend Door Common Driver circuit, (C268) Recirculation Door Driver circuit, and the (C68) Recirculation Door Common Driver circuit between ground and the A/C Heater Control C2 harness connector.
Is the resistance below 10k ohms on any of the circuits?

Yes


- Repair all circuits with a resistance below 10k ohms for a short to ground.
- Perform BODY VERIFICATION TEST - VER 1. Body Verification Test.


No


- Go to 3




3. CHECK THE (C266) MODE DOOR DRIVER CIRCUIT FOR A SHORT TO THE (C255) LEFT BLEND DOOR DRIVER CIRCUIT, (C55) LEFT BLEND DOOR COMMON DRIVER CIRCUIT, (C268) RECIRCULATION DOOR DRIVER CIRCUIT, & THE (C68) RECIRCULATION DOOR COMMON DRIVER CIRCUIT




Measure the resistance between the (C266) Mode Door Driver circuit and the (C255) Left Blend Door Driver circuit, (C55) Left Blend Door Common Driver circuit, (C268) Recirculation Door Driver circuit, and the (C68) Recirculation Door Common Driver circuit in the A/C Heater Control C2 harness connector.
Is the resistance below 10k ohms on any of the circuits?

Yes


- Repair all circuits with a resistance below 10k ohms for a short to the (C266) Mode Door Driver circuit.
- Perform BODY VERIFICATION TEST - VER 1. Body Verification Test.


No


- Go to 4




4. CHECK THE (C66) MODE DOOR COMMON DRIVER CIRCUIT FOR A SHORT TO THE (C255) LEFT BLEND DOOR DRIVER CIRCUIT, (C55) LEFT BLEND DOOR COMMON DRIVER CIRCUIT, (C268) RECIRCULATION DOOR DRIVER CIRCUIT, & THE (C68) RECIRCULATION DOOR COMMON DRIVER CIRCUIT




Measure the resistance between the (C66) Mode Door Common Driver circuit and the (C255) Left Blend Door Driver circuit, (C55) Left Blend Door Common Driver circuit, (C268) Recirculation Door Driver circuit, and the (C68) Recirculation Door Common Driver circuit in the A/C Heater Control C2 harness connector.
Is the resistance below 10k ohms on any of the circuits?

Yes


- Repair all circuits with a resistance below 10k ohms for a short to the (C66) Mode Door Common Driver circuit.
- Perform BODY VERIFICATION TEST - VER 1. Body Verification Test.


No


- Go to 5




5. CHECK THE (C255) LEFT BLEND DOOR DRIVER CIRCUIT FOR A SHORT TO THE (C268) RECIRCULATION DOOR DRIVER CIRCUIT & THE (C68) RECIRCULATION DOOR COMMON DRIVER CIRCUIT




Measure the resistance between the (C255) Left Blend Door Driver circuit and the (C268) Recirculation Door Driver circuit and the (C68) Recirculation Door Common Driver circuit in the A/C Heater Control C2 harness connector.
Is the resistance below 10k ohms on any of the circuits?

Yes


- Repair all circuits with a resistance below 10k ohms for a short to the (C255) Left Blend Door Driver circuit.
- Perform BODY VERIFICATION TEST - VER 1. Body Verification Test.


No


- Go to 6




6. CHECK THE (C55) LEFT BLEND DOOR COMMON DRIVER CIRCUIT FOR A SHORT TO THE (C268) RECIRCULATION DOOR DRIVER CIRCUIT & THE (C68) RECIRCULATION DOOR COMMON DRIVER CIRCUIT




Measure the resistance between the (C55) Left Blend Door Common Driver circuit and the (C268) Recirculation Door Driver circuit and the (C68) Recirculation Door Common Driver circuit in the A/C Heater Control C2 harness connector.
Is the resistance below 10k ohms on any of the circuits?

Yes


- Repair all circuits with a resistance below 10k ohms for a short to the (C55) Left Blend Door Common Driver circuit.
- Perform BODY VERIFICATION TEST - VER 1. Body Verification Test.


No


- Go to 7




7. CHECK THE MODE DOOR ACTUATOR CIRCUIT RESISTANCE




Measure the resistance between the (C66) Mode Door Common Driver Circuit and the (C266) Mode Door Driver circuit in the A/C Heater Control C2 harness connector.
Is the resistance below 30.0 ohms?

Yes


- Go to 8


No


- Go to 9




8. CHECK THE (C66) MODE DOOR COMMON DRIVER CIRCUIT FOR A SHORT TO THE (C266) MODE DOOR DRIVER CIRCUIT




Disconnect the Mode Door Actuator harness connector.
Measure the resistance between the (C66) Mode Door Common Driver Circuit and the (C266) Mode Door Driver circuit in the A/C Heater Control C2 harness connector.
Is the resistance below 10k ohms?

Yes


- Repair the (C66) Mode Door Common Driver Circuit for a short to the (C266) Mode Door Driver circuit.
- Perform BODY VERIFICATION TEST - VER 1. Body Verification Test.


No


- Replace the Mode Door Actuator.
- Perform BODY VERIFICATION TEST - VER 1. Body Verification Test.




9. CHECK THE LEFT BLEND DOOR ACTUATOR CIRCUIT RESISTANCE




Measure the resistance between the (C55) Left Blend Door Common Driver Circuit and the (C255) Left Blend Door Driver circuit in the A/C Heater Control C2 harness connector.
Is the resistance below 30.0 ohms?

Yes


- Go to 10


No


- Go to 11




10. CHECK THE (C55) LEFT BLEND DOOR COMMON DRIVER CIRCUIT FOR A SHORT TO THE (C255) LEFT BLEND DOOR DRIVER CIRCUIT




Disconnect the Left Blend Door Actuator harness connector.
Measure the resistance between the (C55) Left Blend Door Common Driver Circuit and the (C255) Left Blend Door Driver circuit in the A/C Heater Control C2 harness connector.
Is the resistance below 10k ohms?

Yes


- Repair the (C55) Left Blend Door Common Driver Circuit for a short to the (C255) Left Blend Door Driver circuit.
- Perform BODY VERIFICATION TEST - VER 1. Body Verification Test.


No


- Replace the Left Blend Door Actuator.
- Perform BODY VERIFICATION TEST - VER 1. Body Verification Test.




11. CHECK THE RECIRCULATION DOOR ACTUATOR CIRCUIT RESISTANCE




Measure the resistance between the (C68) Recirculation Door Common Driver Circuit and the (C268) Recirculation Door Driver circuit in the A/C Heater Control C2 harness connector.
Is the resistance below 30.0 ohms?

Yes


- Go to 12


No


- Go To 13




12. CHECK THE (C68) RECIRCULATION DOOR COMMON DRIVER CIRCUIT FOR A SHORT TO THE (C268) RECIRCULATION DOOR DRIVER CIRCUIT




Disconnect the Recirculation Door Actuator harness connector.
Measure the resistance between the (C68) Recirculation Door Common Driver Circuit and the (C268) Recirculation Door Driver circuit in the A/C Heater Control C2 harness connector.
Is the resistance below 10k ohms?

Yes


- Repair the (C68) Recirculation Door Common Driver Circuit for a short to the (C268) Recirculation Door Driver circuit.
- Perform BODY VERIFICATION TEST - VER 1. Body Verification Test.


No


- Replace the Recirculation Door Actuator.
- Perform BODY VERIFICATION TEST - VER 1. Body Verification Test.




13. VERIFY THAT THE FAULT IS STILL PRESENT
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 indictor is not illuminated and stored DTCs when the EBL status indicator is illuminated.

Read DTCs from the A/C status indictor.
Does the A/C status indicator display DTC 72?

Yes


- Replace the A/C Heater Control.
- Perform BODY VERIFICATION TEST - VER 1. Body Verification Test.


No


- 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.
- Perform BODY VERIFICATION TEST - VER 1. Body Verification Test.

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