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Home >> Jeep >> 2005 >> Wrangler Rubicon, Standard >> Repair and Diagnosis >> External Pages >> Different car >> Section 571 (Nag1 Automatic Transmission - Electrical Diagnostics) >> DTC Troubleshooting >> U0431-Implausible Data From FCM >> Diagnostic Test

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. 1)  CHECK FOR FCM CAN BUS DTCS 

    With the scan tool, read FCM DTCs.

    Are there any FCM CAN BUS DTC's present? 

    Yes 

    1. Refer to ELECTRONIC CONTROL MODULES - ELECTRICAL DIAGNOSTICS category and perform the appropriate symptom.

    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 .