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Diagnostic Test

WARNING: This page is about a different car, the 2005 Jeep Grand Cherokee. However, it is still accessible from the selected car via links, so may be relevant.
  1. 1)  CHECK THE (C266) FRONT MODE DOOR DRIVER CIRCUIT, (C66) FRONT MODE DOOR COMMON DRIVER CIRCUIT, (C139) REAR MODE DOOR DRIVER CIRCUIT, (C939) REAR 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 
    Fig 1: Checking Front Mode Door, Front Mode Door Common, Rear Mode Door, Rear Mode Door Common, Left Blend Door, Left Blend Door Common, Recirculation Door, & Recirculation Door Common Driver Circuits For Short To Voltage
    GC0028217Courtesy of DAIMLERCHRYSLER CORP.

    Turn the ignition off.

    Disconnect the A/C Heater Control C2 harness connector.

    Turn the ignition on.

    Measure the voltage of the (C266) Front Mode Door Driver circuit, (C66) Front Mode Door Common Driver circuit, (C139) Rear Mode Door Driver circuit, (C939) Rear 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 

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

    No 

    1. Go To step  2).
  2. 2)  CHECK THE (C266) FRONT MODE DOOR DRIVER CIRCUIT, (C66) FRONT MODE DOOR COMMON DRIVER CIRCUIT, (C139) REAR MODE DOOR DRIVER CIRCUIT, (C939) REAR 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 
    Fig 2: Checking Front Mode Door, Front Mode Door Common, Rear Mode Door, Rear Mode Door Common, Left Blend Door, Left Blend Door Common, Recirculation Door, & Recirculation Door Common Driver Circuits For A Short To Ground
    GC0028218Courtesy of DAIMLERCHRYSLER CORP.

    Turn the ignition off.

    Measure the resistance of the (C266) Front Mode Door Driver circuit, (C66) Front Mode Door Common Driver circuit, (C139) Rear Mode Door Driver circuit, (C939) Rear 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 

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

    No 

    1. Go To step  3).
  3. 3)  CHECK THE (C266) FRONT MODE DOOR DRIVER CIRCUIT FOR A SHORT TO THE (C139) REAR MODE DOOR DRIVER CIRCUIT, (C939) REAR MODE DOOR COMMON DRIVER CIRCUIT, (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 
    Fig 3: Checking Front Mode Door Driver Circuit For Short To Other Circuits
    GC0028178Courtesy of DAIMLERCHRYSLER CORP.

    Measure the resistance between the (C266) Front Mode Door Driver circuit and the (C139) Rear Mode Door Driver circuit, (C939) Rear 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 in the A/C Heater Control C2 harness connector.

    Is the resistance below 10k ohms on any of the circuits? 

    Yes 

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

    No 

    1. Go To step  4).
  4. 4)  CHECK THE (C66) FRONT MODE DOOR COMMON DRIVER CIRCUIT FOR A SHORT TO THE (C139) REAR MODE DOOR DRIVER CIRCUIT, (C939) REAR MODE DOOR COMMON DRIVER CIRCUIT, (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 
    Fig 4: Checking Front Mode Door Common Driver Circuit For Short To Other Circuits
    GC0028179Courtesy of DAIMLERCHRYSLER CORP.

    Measure the resistance between the (C66) Front Mode Door Common Driver circuit and the (C139) Rear Mode Door Driver circuit, (C939) Rear 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 in the A/C Heater Control C2 harness connector.

    Is the resistance below 10k ohms on any of the circuits? 

    Yes 

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

    No 

    1. Go To step  5).
  5. 5)  CHECK THE (C139) REAR 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 
    Fig 5: Checking Rear Mode Door Driver Circuit For Short To Left Blend Door Driver Circuit, Left Blend Door Common Driver Circuit, Recirculation Door Driver Circuit, & Recirculation Door Common Driver Circuit
    GC0028180Courtesy of DAIMLERCHRYSLER CORP.

    Measure the resistance between the (C139) Rear 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 

    1. Repair all circuits with a resistance below 10k ohms for a short to the (C139) Rear Mode Door Driver circuit.
    2. Perform BODY VERIFICATION TEST - VER 1 .

    No 

    1. Go To step  6).
  6. 6)  CHECK THE (C939) REAR 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 
    Fig 6: Checking Rear Mode Door Common Driver Circuit For Short To Left Blend Door Driver Circuit, Left Blend Door Common Driver Circuit, Recirculation Door Driver Circuit, & Recirculation Door Common Driver Circuit
    GC0028181Courtesy of DAIMLERCHRYSLER CORP.

    Measure the resistance between the (C939) Rear Mode Door Common Driver circuit and (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 

    1. Repair all circuits with a resistance below 10k ohms for a short to the (C939) Rear Mode Door Common Driver circuit.
    2. Perform BODY VERIFICATION TEST - VER 1 .

    No 

    1. Go To step  7).
  7. 7)  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 
    Fig 7: Checking Left Blend Door Driver Circuit For Short To Recirculation Door Driver Circuit & Recirculation Door Common Driver Circuit
    GC0028182Courtesy of DAIMLERCHRYSLER CORP.

    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 

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

    No 

    1. Go To step  8).
  8. 8)  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 
    Fig 8: Checking Left Blend Door Common Driver Circuit For Short To Recirculation Door Driver Circuit & Recirculation Door Common Driver Circuit
    GC0028183Courtesy of DAIMLERCHRYSLER CORP.

    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 

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

    No 

    1. Go To step  9).
  9. 9)  CHECK THE FRONT MODE DOOR ACTUATOR CIRCUIT RESISTANCE 
    Fig 9: Checking Front Mode Door Actuator Circuit Resistance
    GC0028184Courtesy of DAIMLERCHRYSLER CORP.

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

    Is the resistance below 30.0 ohms? 

    Yes 

    1. Go To step  10).

    No 

    1. Go To step  11).
  10. 10)  CHECK THE (C66) FRONT MODE DOOR COMMON DRIVER CIRCUIT FOR A SHORT TO THE (C266) FRONT MODE DOOR DRIVER CIRCUIT 
    Fig 10: Checking Front Mode Door Actuator Circuit Resistance
    GC0028184Courtesy of DAIMLERCHRYSLER CORP.

    Disconnect the Front Mode Door Actuator harness connector.

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

    Is the resistance below 10k ohms? 

    Yes 

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

    No 

    1. Replace the Front Mode Door Actuator in accordance with the Service Information.
    2. Perform BODY VERIFICATION TEST - VER 1 .
  11. 11)  CHECK THE REAR MODE DOOR ACTUATOR CIRCUIT RESISTANCE 
    Fig 11: Checking Rear Mode Door Actuator Circuit Resistance
    GC0028185Courtesy of DAIMLERCHRYSLER CORP.

    Measure the resistance between the (C939) Rear Mode Door Common Driver Circuit and the (C139) Rear Mode Door Driver circuit in the A/C Heater Control C2 harness connector.

    Is the resistance below 30.0 ohms? 

    Yes 

    1. Go To step  12).

    No 

    1. Go To step  13).
  12. 12)  CHECK THE (C939) REAR MODE DOOR COMMON DRIVER CIRCUIT FOR A SHORT TO THE (C139) REAR MODE DOOR DRIVER CIRCUIT 
    Fig 12: Checking Rear Mode Door Actuator Circuit Resistance
    GC0028185Courtesy of DAIMLERCHRYSLER CORP.

    Disconnect the Rear Mode Door Actuator harness connector.

    Measure the resistance between the (C939) Rear Mode Door Common Driver Circuit and the (C139) Rear Mode Door Driver circuit in the A/C Heater Control C2 harness connector.

    Is the resistance below 10k ohms? 

    Yes 

    1. Repair the (C939) Rear Mode Door Common Driver Circuit for a short to the (C139) Rear Mode Door Driver circuit.
    2. Perform BODY VERIFICATION TEST - VER 1 .

    No 

    1. Replace the Rear Mode Door Actuator in accordance with the Service Information.
    2. Perform BODY VERIFICATION TEST - VER 1 .
  13. 13)  CHECK THE LEFT BLEND DOOR ACTUATOR CIRCUIT RESISTANCE 
    Fig 13: Checking Left Blend Door Actuator Circuit Resistance
    GC0028186Courtesy of DAIMLERCHRYSLER CORP.

    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 

    1. Go To step  14).

    No 

    1. Go To step  15).
  14. 14)  CHECK THE (C55) LEFT BLEND DOOR COMMON DRIVER CIRCUIT FOR A SHORT TO THE (C255) LEFT BLEND DOOR DRIVER CIRCUIT 
    Fig 14: Checking Left Blend Door Common Driver Circuit For Short To Left Blend Door Driver Circuit
    GC0028186Courtesy of DAIMLERCHRYSLER CORP.

    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 

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

    No 

    1. Replace the Left Blend Door Actuator in accordance with the Service Information.
    2. Perform BODY VERIFICATION TEST - VER 1 .
  15. 15)  CHECK THE RECIRCULATION DOOR ACTUATOR CIRCUIT RESISTANCE 
    Fig 15: Checking Recirculation Door Actuator Circuit Resistance
    GC0028187Courtesy of DAIMLERCHRYSLER CORP.

    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  

    1. Go To step  16).

    No  

    1. Go To step  17).
  16. 16)  CHECK THE (C68) RECIRCULATION DOOR COMMON DRIVER CIRCUIT FOR A SHORT TO THE (C268) RECIRCULATION DOOR DRIVER CIRCUIT 
    Fig 16: Checking Recirculation Door Actuator Circuit Resistance
    GC0028187Courtesy of DAIMLERCHRYSLER CORP.

    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  

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

    No  

    1. Replace the Recirculation Door Actuator in accordance with the Service Information.
    2. Perform BODY VERIFICATION TEST - VER 1 .
  17. 17)  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 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 for 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 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 

    1. Replace the A/C Heater Control in accordance with the Service Information.
    2. Perform BODY VERIFICATION TEST - VER 1 .

    No 

    1. 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 DIAGNOSTIC CODE INDEX for a complete list of HVAC related symptoms.
    2. Perform BODY VERIFICATION TEST - VER 1 .
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