Diagnostic Test

1) CHECK THE STATUS OF THE ERROR MESSAGE
NOTE: Ensure the vehicle being tested is a CAN BUS VEHICLE. If not, false error messages may be displayed.

NOTE: Ensure the scan tool is updated to the latest software.

With the scan tool, record the error message.

Disconnect the scan tool from the DLC.

Cycle the ignition from on to off 3 times.

Turn the ignition on.

Does the scan tool display this same error message?

Yes
1. Go To step 2).
No
1. The conditions that caused this error message to set are not present at this time. Using the wiring diagram/schematic as a guide, inspect the wiring and connectors.
2) (D72) CAN C DIAGNOSTIC (+) CIRCUIT OPEN

Fig 1: Checking CAN C Diagnostic (+) Circuit
Courtesy of DAIMLERCHRYSLER CORP.

Turn the ignition off.

Disconnect the Front Control Module C1 harness connector.

Disconnect the scan tool from the DLC.

NOTE: Check the connectors at both the DLC and the FCM.

Measure the resistance of the (D72) CAN C Diagnostic (+) circuit between the FCM connector and the DLC.

Is the resistance below 5.0 ohms?

Yes
1. Go To step 3).
No
1. Repair the (D72) CAN C Diagnostic (+) circuit for an open.
2. Perform BODY VERIFICATION TEST - VER 1 .
3) (D71) CAN C DIAGNOSTIC (-) CIRCUIT OPEN

Fig 2: Checking CAN C Diagnostic (-) Circuit
Courtesy of DAIMLERCHRYSLER CORP.

Measure the resistance of the (D71) CAN C Diagnostic (-) circuit between the FCM connector and the DLC.

Is the resistance below 5.0 ohms?

Yes
1. Inspect the wiring and connectors for damage or shorted circuits. If OK, replace and program the Front Control Module. Refer to MODULE-FRONT CONTROL .
2. Perform BODY VERIFICATION TEST - VER 1 .
No
1. Repair the (D71) CAN C Diagnostic (-) circuit for an open.
2. Perform BODY VERIFICATION TEST - VER 1 .