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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)  TEST FOR INTERMITTENT CONDITION 

    Turn the ignition on.

    With the scan tool, record and erase FCM DTC's.

    Cycle the ignition from on to off 3 times.

    Turn the ignition on.

    With the scan tool, read active FCM DTC's.

    Does the scan tool display U0002-CAN C BUS OFF PERFORMANCE as active? 

    Yes 

    1. Go To step  2).

    No 

    1. The conditions that caused this code to set are not present at this time. Using the wiring diagram/schematic as a guide, inspect the wiring and connectors.
  2. 2)  ANTILOCK BRAKE MODULE - INTERNAL SHORT 

    Turn the ignition off.

    Disconnect the Antilock Brake Module harness connector.

    Turn the ignition on.

    With the scan tool, record and erase FCM DTC's.

    Cycle the ignition from on to off 3 times.

    Turn the ignition on.

    With the scan tool, read active FCM DTC's.

    Does the scan tool display U0002-CAN C BUS OFF PERFORMANCE as active? 

    Yes 

    1. Go To step  3).

    No 

    1. Inspect the wiring and connectors for damage or shorted circuits. If OK, replace the Antilock Brake Module in accordance with the service information.
    2. Perform ABS VERIFICATION TEST - VER 1 .
  3. 3)  POWERTRAIN CONTROL MODULE - INTERNAL SHORT 

    Turn the ignition off.

    Disconnect the Powertrain Control Module C1 harness connector.

    Turn the ignition on.

    With the scan tool, record and erase FCM DTC's.

    Cycle the ignition from on to off 3 times.

    Turn the ignition on.

    With the scan tool, read active FCM DTC's.

    Does the scan tool display U0002-CAN C BUS OFF PERFORMANCE as active? 

    Yes 

    1. Go To step  4).

    No 

    1. Inspect the wiring and connectors for damage or shorted circuits. If OK, replace and program the Powertrain Control Module in accordance with the service information.
    2. Perform POWERTRAIN VERIFICATION TEST VER - 5 .
  4. 4)  SHIFTER LEVER ASSEMBLY (NAG1 ONLY)- INTERNAL SHORT 

    Turn the ignition off.

    NOTE: If the vehicle is not equipped with a NAG1 controller then skip this step.

    Disconnect the Shifter Lever Assembly harness connector.

    Turn the ignition on.

    With the scan tool, record and erase FCM DTC's.

    Cycle the ignition from on to off 3 times.

    Turn the ignition on.

    With the scan tool, read active FCM DTC's.

    Does the scan tool display U0002-CAN C BUS OFF PERFORMANCE as active? 

    Yes 

    1. Go To step  5).

    No 

    1. Inspect the wiring and connectors for damage or shorted circuits. If OK, replace and program the Shifter Lever Assembly in accordance with the service information.
    2. Perform NAG1 TRANSMISSION VERIFICATION TEST - VER 1 .
  5. 5)  TRANSMISSION CONTROL MODULE (NAG1 ONLY)- INTERNAL SHORT 

    Turn the ignition off.

    NOTE: If the vehicle is not equipped with a NAG1 controller then skip this step.

    Disconnect the Transmission Control Module C2 harness connector.

    Turn the ignition on.

    With the scan tool, record and erase FCM DTC's.

    Cycle the ignition from on to off 3 times.

    Turn the ignition on.

    With the scan tool, read active FCM DTC's.

    Does the scan tool display U0002-CAN C BUS OFF PERFORMANCE as active? 

    Yes 

    1. Go To step  6).

    No 

    1. Inspect the wiring and connectors for damage or shorted circuits. If OK, replace and program the Transmission Control Module in accordance with the service information.
    2. Perform NAG1 TRANSMISSION VERIFICATION TEST - VER 1 .
  6. 6)  STEERING CONTROL MODULE - INTERNAL SHORT 

    Turn the ignition off.

    Disconnect the Steering Control Module harness connector.

    Turn the ignition on.

    With the scan tool, record and erase FCM DTC's.

    Cycle the ignition from on to off 3 times.

    Turn the ignition on.

    With the scan tool, read active FCM DTC's.

    Does the scan tool display U0002-CAN C BUS OFF PERFORMANCE as active? 

    Yes 

    1. Go To step  7).

    No 

    1. Inspect the wiring and connectors for damage or shorted circuits. If OK, replace and program the Steering Control Module in accordance with the service information.
    2. Perform BODY VERIFICATION TEST - VER 1 .
  7. 7)  (D65) CAN C BUS (+) CIRCUIT SHORTED TO VOLTAGE 
    Fig 1: Checking CAN C BUS (+) Circuit
    GC0026992Courtesy of DAIMLERCHRYSLER CORP.

    Turn the ignition off.

    Disconnect the Front Control Module C1 harness connector.

    Turn the ignition on.

    Measure the voltage between the (D65) CAN C Bus (+) circuit and ground.

    Is there any voltage present? 

    Yes 

    1. Repair the (D65) CAN C Bus (+) circuit for a short to voltage.
    2. Perform BODY VERIFICATION TEST - VER 1 .

    No 

    1. Go To step  8).
  8. 8)  (D64) CAN C BUS (-) CIRCUIT SHORTED TO VOLTAGE 
    Fig 2: Checking CAN C BUS (-) Circuit
    GC0026993Courtesy of DAIMLERCHRYSLER CORP.

    Measure the voltage between the (D64) CAN C Bus (-) circuit and ground.

    Is there any voltage present? 

    Yes 

    1. Repair the (D64) CAN C Bus (-) circuit for a short to voltage.
    2. Perform BODY VERIFICATION TEST - VER 1 .

    No 

    1. Go To step  9).
  9. 9)  (D65) CAN C BUS (+) CIRCUIT SHORTED TO GROUND 
    Fig 3: Checking CAN C BUS (+) Circuit
    GC0026994Courtesy of DAIMLERCHRYSLER CORP.

    Turn the ignition off.

    Measure the resistance between ground and the (D65) CAN C Bus (+) circuit.

    Is any resistance present? 

    Yes 

    1. Repair the (D65) CAN C Bus (+) circuit for a short to ground.
    2. Perform BODY VERIFICATION TEST - VER 1 .

    No 

    1. Go To step  10).
  10. 10)  (D64) CAN C BUS (-) CIRCUIT SHORTED TO GROUND 
    Fig 4: Checking CAN C BUS (-) Circuit
    GC0026995Courtesy of DAIMLERCHRYSLER CORP.

    Measure the resistance between ground and the (D64) CAN C Bus (-) circuit.

    Is any resistance present? 

    Yes 

    1. Repair the (D64) CAN C Bus (-) circuit for a short to ground.
    2. Perform BODY VERIFICATION TEST - VER 1 .

    No 

    1. Go To step  11).
  11. 11)  (D65) CAN C BUS (+) CIRCUIT SHORTED TO (D64) CAN C BUS (-) CIRCUIT 
    Fig 5: Checking CAN C BUS (+) Circuit
    GC0026996Courtesy of DAIMLERCHRYSLER CORP.

    Measure the resistance between the (D65) CAN C Bus (+) circuit and the (D64) CAN C Bus (-) circuit.

    Is any resistance present? 

    Yes 

    1. Repair the (D65) CAN C Bus (+) circuit for a short to the (D64) CAN C Bus (-) circuit.
    2. Perform BODY VERIFICATION TEST - VER 1 .

    No 

    1. Inspect the wiring and connectors for damage or shorted circuits. If OK, replace and program the Front Control Module in accordance with the service information.
    2. Perform BODY VERIFICATION TEST - VER 1 .
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