Diagnostic Test

WARNING: This page is about a different car, the 2005 Jeep Grand Cherokee. However, it is still accessible from the selected car via links, so may be relevant.

1) CHECK FOR INTERNAL TRANSMISSION PROBLEM
Determine if there are any Transmission mechanical problems present.

Remove the Transmission Oil Pan and inspect for excessive debris or a plugged Transmission Oil Filter. Refer to SERVICE INFORMATION - NAG1 for the appropriate service procedure

Is there any Transmission mechanical problems present?

Yes
1. Repair as necessary. Refer to SERVICE INFORMATION - NAG1 for the appropriate service procedure.
2. Perform NAG1 TRANSMISSION VERIFICATION TEST - VER 1 .
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 the TCM per the Service Information. Refer to ELECTRONIC CONTROL MODULES - SERVICE INFORMATION for the appropriate service procedure.
2. Perform NAG1 TRANSMISSION VERIFICATION TEST - VER 1 .