Diagnostic Procedure
WARNING: This page is about a different car, the 2005 Jeep Liberty. However, it is still accessible from the selected car via links, so may be relevant.
DIAGNOSTIC PROCEDURES - LOST COMMUNICATION WITH ECM [FCM] (DIESEL ONLY)
| TEST | ACTION | APPLICABILITY |
|---|---|---|
| 1 | Turn the ignition on. With the DRB, attempt to communicate with the ECM. Was the DRB able to I/D or communicate with the module? Yes --> Go To 2 No --> Refer to the COMMUNICATION category for the related symptom(s). Perform ROAD TEST VERIFICATION - VER-2 . |
All |
| 2 | With the DRB, erase DTC's. Start the engine and wait approximately 1 minute. With the DRB, read DTC's. Did this DTC reset? Yes --> Go To 3 No --> No problem found at this time. Using the wiring diagrams as a guide, visually check the CAN Bus circuits for chafed, pierced, pinched, and partially broken wires and the wiring harness connectors for proper connection. Repair as necessary. Perform ROAD TEST VERIFICATION - VER-2 . |
All |
| 3 | Turn the ignition off and wait 1 minute. Disconnect the FCM harness connector. Disconnect the ECM C2 harness connector. Measure the resistance of the CAN C Bus (+) circuit between the FCM harness connector and the ECM harness connector. Is the resistance below 5.0 ohms? Yes --> Go To 4 No --> Repair the CAN C Bus (+) circuit for an open. Perform ROAD TEST VERIFICATION - VER-2 . |
All |
| 4 | Turn the ignition off and wait 1 minute. Disconnect the FCM harness connector. Disconnect the ECM C2 harness connector. Measure the resistance of the CAN C Bus (-) circuit between the FCM harness connector and the ECM harness connector. Is the resistance below 5.0 ohms? Yes --> Replace the Engine Control Module in accordance with the service information. Perform ROAD TEST VERIFICATION - VER-2 . No --> Repair the CAN C Bus (-) circuit for an open. Perform ROAD TEST VERIFICATION - VER-2 . |
All |