U1401

U1401-IMPLAUSIBLE ENGINE SPEED SIGNAL RECEIVED

For a complete wiring diagram, refer to the Wiring Information.

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 AS68RC Pre-Diagnostic Troubleshooting procedure before proceeding. AS68RC Pre-Diagnostic Troubleshooting Procedure

1. CHECK FOR TIPM CAN BUS DTCs
1. With the scan tool, read TIPM DTCs.

Are there any TIPM CAN BUS DTCs present?

Yes

- Refer to DTC Based Diagnostics and perform the appropriate diagnostic procedure.
- Perform AS68RC TRANSMISSION VERIFICATION TEST. AS68RC Transmission Verification Test

No

- Go To 2

2. CHECK IF ENGINE DTCs ARE PRESENT
1. With the scan tool, read engine DTCs.

Are there any engine DTCs present?

Yes

- Refer to DTC Based Diagnostics and perform the appropriate diagnostic procedure.
- Perform AS68RC TRANSMISSION VERIFICATION TEST. AS68RC 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 and program the TCM.
- Perform AS68RC TRANSMISSION VERIFICATION TEST. AS68RC Transmission Verification Test