U1401

U1401-IMPLAUSIBLE ENGINE SPEED SIGNAL RECEIVED

For a complete wiring diagram Consult Diagrams/Electrical

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 ID received at least once, and no U0002-CAN Bus Off Performance DTC present.

- Set Condition:
When the TCM detects an incorrect CAN ID from the ECM/PCM.





Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Initial Inspection and Diagnostic Overview

Diagnostic Test

1. CHECK FOR FCM CAN BUS DTCS
With the scan tool, read FCM DTCs.
Are there any FCM CAN BUS DTCs present?

Yes

- Diagnose and repair the DTC(s).
- Perform NAG1 TRANSMISSION VERIFICATION TEST.Verification Tests

No

- Go to 2

2. CHECK IF ENGINE DTCS ARE PRESENT
With the scan tool, read engine DTCs.
Are there any engine DTCs present?

Yes

- Diagnose and repair the DTC(s).
- Perform NAG1 TRANSMISSION VERIFICATION TEST.Verification Tests

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 and program the TCM.
- Perform NAG1 TRANSMISSION VERIFICATION TEST.Verification Tests