U1508 Implausible messages data length received from ESM

U1508 code - 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 this DTC continuously with the ignition on, one valid can id received at least once, and no U0002 can bus off performance DTC present. Set condition this DTC when the TCM detects an incorrect can id from the electronic shift module (ESM).

Possible causes U1508 code:

- Can Bus DTCs present

- Electronic shift module DTCs present

- Transmission control module (TCM)

Diagnostic test U1508 code

Step 1. Check for Can Bus DTCs 

With the scan tool, check for Can Bus DTCs.

Are the scan tool any ESM DTCs present?

Yes, perform Perform NAG1 Transmission Verification Test.

No, go to step 2.

Step 2. Electronic shift module DTCs present

With the scan tool, read electronic shift module (ESM) DTCs.

Are there any ESM DTCs present ?

Yes, refer to 28 DTC based diagnostics/module, electronic shift (ESM) diagnosis and testing and perform the appropriate diagnostic procedure.

No, using the schematics as a guide, check the transmission control module (TCM) pins, terminals, and connectors for corrosion, damage, or termial push out. Pay particular attention to all power and ground circuits. If no problems are found, replace and program the TCM in accordance with the service information. Perform NAG1 Transmission Verification Test.

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