NAG1 Automatic Transmission

U0401-IMPLAUSIBLE DATA RECEIVED FROM ECM/PCM

For a complete wiring diagram refer to Diagrams/Electrical. Electrical Diagrams


Theory of Operation


The messages sent on the CAN bus are distinguished by an identifier (ID). Each CAN ID is defined to contain a certain number of bytes. The Transmission Control Module (TCM) verifies that it has received the proper number of bytes for each ID.


- When Monitored:

Continuously with the ignition on, one valid CAN message received at least once, and no U0002-CAN C Bus Off Performance DTC present.

- Set Condition:

When the TCM detects an incorrect CAN message from the Engine Control Module (ECM).







Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. NAG1 - Pre-Diagnostic Troubleshooting Procedure


Diagnostic Test


1. CHECK IF FCM CAN BUS DTC'S ARE PRESENT

With the scan tool, read FCM DTCs.

Are there any FCM CAN BUS DTC's present?

Yes

- Refer to Communications category and perform the appropriate symptom.
- Perform NAG1 TRANSMISSION VERIFICATION TEST. NAG1 Transmission Verification Test

No

- Go To 2


2. CHECK IF ENGINE DTC'S ARE PRESENT

With the scan tool, read Engine DTCs.

Are there any Engine DTC's present?

Yes

- Refer to the ENGINE and diagnose the appropriate symptom(s).
- Perform NAG1 TRANSMISSION VERIFICATION TEST. NAG1 Transmission Verification Test

No

- 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.
- Perform NAG1 TRANSMISSION VERIFICATION TEST. NAG1 Transmission Verification Test