Diagnostic Test

1) CHECK FOR FCM CAN BUS DTCS
With the scan tool, read FCM DTCs.

Are there any FCM CAN BUS DTCs present?

Yes
1. Refer to DIAGNOSIS AND TESTING and perform the appropriate symptom.
2. Perform NAG1 TRANSMISSION VERIFICATION TEST .
No
1. Go to 2).
2) ELECTRONIC SHIFT MODULE DTCS PRESENT
With the scan tool, read Electronic Shift Module (ESM) DTCs.

Are there any ESM DTCs present?

Yes
1. Refer to NAG1 - SHIFTER DIAGNOSTICS article and perform the appropriate diagnostic procedure.
No
1. Using the schematics as a guide, check the Transmission Control Module (TCM) pins, terminals, and connectors 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 per the Service Information. Refer to MODULE-TRANSMISSION CONTROL .
2. Perform NAG1 TRANSMISSION VERIFICATION TEST .