Transmission Control Module (TCM)

U0002-CAN C BUS OFF PERFORMANCE

For a complete wiring diagram, refer to the Wiring Information.

Theory of Operation

The Transmission Control Module (TCM) receives information from the Engine, Anti-lock Brake System, and the Electronic Gear Shift control modules over the CAN C bus. The CAN C bus is a high speed communication bus that allows real time control capability between various controllers. Most messages are sent every 20 msec., this means critical information can be shared between controllers. The CAN C bus is a two wire bus with a CAN (+) and a CAN (-) circuit. To reduce the potential of radio and other electrical noise interference, the CAN Bus circuit wiring is manufactured in a twisted pair within the electrical harness.

- When Monitored:
Continuously with the ignition on.

- Set Condition:
The TCM detects an: open, short to ground, short to voltage of the CAN C (+) or CAN C (-) circuits, short between the CAN C (+) or CAN C (-) circuits.





Always perform the NAG1 Pre-Diagnostic Troubleshooting procedure before proceeding. Initial Inspection and Diagnostic Overview.

1. CHECK TIPM FOR AN OVERALL CAN COMMUNICATION BUS FAILURE
1. With the scan tool, check for TIPM DTCs.

Does the TIPM report a CAN C Bus failure, or one or more CAN C Bus DTCs?

Yes

- Perform the appropriate diagnostic procedure. Perform the diagnostic procedure for U0001-CAN C BUS DTC first if it is present.
- Perform the NAG1 TRANSMISSION VERIFICATION TEST. NAG1 Transmission Verification Test.

No

- Go To 2

2. CHECK IF THE DTC IS CURRENT

NOTE: When the Transmission Control Module (TCM) detects and stores a DTC, the TCM also stores the vehicles operating conditions under which the DTC originally set. This information is located in the scan tool under Environmental Data. Before erasing any stored DTCs, record any available data to assist in duplicating the conditions in which the DTC originally set.

1. Ignition on, engine not running.
2. With the scan tool, erase Transmission DTCs.
3. Using the Environmental Data recorded earlier, try to duplicate the conditions in which the DTC originally set. It may be necessary to test drive the vehicle.
4. With the scan tool, read Transmission DTCs.

Did the DTC U0002-CAN C BUS OFF PERFORMANCE reset?

Yes

- Using the schematics as a guide, check the Transmission Control Module (TCM) connectors and terminals for corrosion, damage, or terminal push out. Pay particular attention to all power and ground circuits. If no problems are found, replace and program the TCM.
- Perform NAG1 TRANSMISSION VERIFICATION TEST. NAG1 Transmission Verification Test.

No

- Go To 3

3. INTERMITTENT WIRING AND CONNECTORS
1. The conditions necessary to set this DTC are not present at this time.
2. Using the schematics as a guide, inspect the wiring and connectors specific to this circuit.
3. Wiggle the wiring and connectors while checking for any possible open or shorted circuits.
4. Check for any Service Information Tune-ups or Technical Service Bulletins that may apply.

Were there any problems found?

Yes

- Repair as necessary.
- Perform the NAG1 TRANSMISSION VERIFICATION TEST. NAG1 Transmission Verification Test.

No

- Test Complete.