Diagnostic Test

WARNING: This page is about a different car, the 2009 Jeep Grand Cherokee. However, it is still accessible from the selected car via links, so may be relevant.

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.
1. With the scan tool, record the error message.
2. Disconnect the scan tool from the DLC.
3. Cycle the ignition from on to off 3 times.
4. Turn the ignition on.
  Does the scan tool display this same error message?
  
  Yes
  - Go to step 2
  No
  - 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.
(D71) DIAGNOSTIC CAN C (-) CIRCUIT OPEN

Fig 1: Checking Diagnostic Can C (-) Circuit For Open
Courtesy of CHRYSLER LLC
1. Turn the ignition off.
2. Disconnect the Front Control Module C1 harness connector.
3. Disconnect the scan tool from the DLC.
4. Measure the resistance of the (D71) Diagnostic CAN C (-) circuit between the FCM connector and the DLC.
  Is the resistance below 5.0 ohms?
  
  Yes
  - Inspect the wiring and connectors for damage or shorted circuits. If ok, replace the Front Control Module in accordance with the Service Information.
  - Perform the BODY VERIFICATION TEST. Refer to DTC-Based Diagnostics/MODULE, Front Control (FCM) - Standard Procedure
  No
  - Repair the (D71) Diagnostic CAN C (-) circuit for an open.
  - Perform the BODY VERIFICATION TEST. Refer to DTC-Based Diagnostics/MODULE, Front Control (FCM) - Standard Procedure