Diagnostic Test

CHECK FCM FOR AN OVERALL CAN COMMUNICATION BUS FAILURE
1. With the scan tool, check for FCM DTCs.
  Does the FCM report a CAN C Bus failure, or one or more CAN C Bus DTCs?
  
  Yes
  - Refer to the appropriate Electrical Diagnostics article for diagnostic procedures and other possible causes. Perform the diagnostic procedure for U0001-CAN C BUS DTC first if it is present.
  - Perform NAG1 TRANSMISSION VERIFICATION TEST. Refer to Standard Procedure .
  No
  - Go to 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) terminals for corrosion, damage, or terminal push out. Pay particular attention to all power and ground circuits. If no problems are found, replace the TCM in accordance with the Service Information.
  - Perform NAG1 TRANSMISSION VERIFICATION TEST. Refer to Standard Procedure .
  No
  - Go to 3.
CHECK THE 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 NAG1 TRANSMISSION VERIFICATION TEST. Refer to Standard Procedure .
  No
  - Test Complete.