U1401 Implausible engine speed signal received

U1401 code - 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 ECM/PCM.

Possible causes U1401 code:

- TIPM Can Bus DTCs present

- Engine module DTCs present

- Transmission control module

Diagnostic test U1401 code

Step 1. Check for TIPM Can Bus DTCs

With the scan tool, read TIPM DTCs. 

Are there any TIPM Can Bus DTCs present ?

Yes, perform NAG1 Transmission Verification Test.

No, go to step 2.

Step 2. Check if engine DTCs are present

With the scan tool, read engine DTCs.

Are there any engine DTCs present ?

Yes, perform NAG1 Transmission Verification Test.

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

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