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.

TEST FOR INTERMITTENT CONDITION
1. Turn the ignition on.
  NOTE: Ensure the IOD fuse is installed and battery voltage is between 10.0 and 16.0 volts.
2. With the scan tool, select ECU view.
  NOTE: A red "X" will be next to the module that is not communicating, indicating that the module is not active on the Bus network. A green check indicates that the module is active on the Bus network.
  
  NOTE: Check the FCM for any active CAN C hardware and any ignition related DTCs, perform DTCs before proceeding.
  
  Does the scan tool display a red "X" next to the module?
  
  Yes
  - Go to step 2
  No
  - The no response condition is not present at this time. Using the wiring diagram/schematic as a guide, inspect the wiring for chafed, pierced, pinched, and partially broken wires and the wiring harness connectors for broken, bent, pushed out, and corroded terminals.
CHECK ECM POWER AND GROUND
1. Check the ECM power and ground circuits. Refer to Non-DTC Diagnostics/Driveability - Diesel - Diagnosis and Testing
  Were any problems found?
  
  Yes
  - Repair as necessary.
  - Perform the ECM VERIFICATION TEST. Refer to DTC-Based Diagnostics/MODULE, Engine Control (ECM) - Standard Procedure
  No
  - Go to step 3
(D65) CAN C BUS (+) CIRCUIT OPEN

Fig 1: Checking Can C Bus (+) Circuit For Open
Courtesy of CHRYSLER LLC
1. Turn the ignition off.
2. Disconnect the FCM C1 harness connector.
3. Disconnect the ECM C2 harness connector.
4. Measure the resistance of the (D65) CAN C Bus (+) circuit between the FCM connector and the ECM connector.
  Is resistance below 5.0 ohms?
  
  Yes
  - Go to step 4
  No
  - Repair the (D65) CAN C Bus (+) circuit for an open.
  - Perform the ECM VERIFICATION TEST. Refer to DTC-Based Diagnostics/MODULE, Engine Control (ECM) - Standard Procedure
(D64) CAN C BUS (-) CIRCUIT OPEN

Fig 2: Checking Can C Bus (-) Circuit For Open
Courtesy of CHRYSLER LLC
1. Measure the resistance of the (D64) CAN C Bus (-) circuit between the FCM connector and the ECM connector.
  Is resistance below 5.0 ohms?
  
  Yes
  - Replace and program the Engine Control Module in accordance with the Service Information.
  - Perform the ECM VERIFICATION TEST. Refer to DTC-Based Diagnostics/MODULE, Engine Control (ECM) - Standard Procedure
  No
  - Repair the (D64) CAN C Bus (-) circuit for an open.
  - Perform the ECM VERIFICATION TEST. Refer to DTC-Based Diagnostics/MODULE, Engine Control (ECM) - Standard Procedure