Diagnostic Test
- 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.
Q: Does the scan tool display this DTC as active?
Yes :
- Go To 2
No :
- 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.
- ATTEMPT TO ISOLATE THE OPEN CONDITION
- Turn the ignition on.
- Verify that all CAN B Bus modules are communicating with the scan tool.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: If any module is not communicating, perform the appropriate no response test procedure before proceeding.
- Turn the ignition off.
- Gain access to the Front Control Module C1 harness connector, but do not disconnect.
- Using a fused jumper wire, connect one end to ground and with the other end backprobe the CAN B Bus (+) circuit at the FCM C1 harness connector.
- Turn the ignition on.
- With the scan tool monitor the network status screen and document all modules that display a red X.
Q: Are there any red X's displayed next to the modules?
Yes :
- Go To 3
No :
- Check backprobe connection to ground, make sure it is proper. The CAN B Bus open DTC may no longer be active, it may be stored. Check all module connections
- Perform BODY VERIFICATION TEST - VER 1 . (Refer to DIAGNOSIS AND TESTING ).
- ATTEMPT TO ISOLATE THE OPEN CONDITION - MULTIPLE RED X'S
- With the scan tool continue monitoring the network status screen.
Q: Are there multiple red X's displayed next to the modules?
Yes :
- The most likely cause of this condition is an open CAN B Bus (-) circuit between a common CAN B Bus splice and the modules that display the red X next to them. Use the wiring diagrams will help you determine where open condition exists.
- Perform BODY VERIFICATION TEST - VER 1 . (Refer to DIAGNOSIS AND TESTING ).
No :
- Go To 4
- (D54) CAN B BUS (-) CIRCUIT OPEN - SINGLE RED
- Turn the ignition off.
- Disconnect the module that has the red X displayed next to it.
- Turn the ignition on.
- Measure the voltage between the (D54) CAN B Bus (-) circuit and ground.
Q: Is there any voltage present?
Yes :
- Inspect the connector and terminal for damage, inspect for spread terminals, or push out terminals. If OK, replace the module that displayed the red X next to it in accordance with the service information.
- Perform BODY VERIFICATION TEST - VER 1 . (Refer to DIAGNOSIS AND TESTING ).
No :
- Repair the (D54) CAN B Bus (-) circuit for an open between the next common splice and the module that has the red X displayed next to it. Use the wiring diagrams will help you determine where open condition exists.
- Perform BODY VERIFICATION TEST - VER 1 . (Refer to DIAGNOSIS AND TESTING ).