U0404
U0404-IMPLAUSIBLE DATA RECEIVED FROM ESMWiring Diagram:
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 Electronic Shift Module (ESM).
Possible Causes
FCM CAN BUS DTC'S PRESENT
ELECTRONIC SHIFT MODULE DTC'S PRESENT
TRANSMISSION CONTROL MODULE
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Initial Inspection
Diagnostic Test
1. CHECK FOR FCM CAN BUS DTCS
With the scan tool, read FCM DTCs.
Are there any FCM CAN BUS DTC's present?
Yes >> Perform the appropriate test.
No >> Go To 2
2. ELECTRONIC SHIFT MODULE DTC IS PRESENT
With the scan tool, read Electronic Shift Module (ESM) DTCs.
Are there any ESM DTC's present?
Yes >> Refer to Trouble Code Diagnostic Charts and perform the appropriate diagnostic procedure. Perform NAG1 TRANSMISSION VERIFICATION TEST - VER 1. 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 the TCM. Perform NAG1 TRANSMISSION VERIFICATION TEST - VER 1. Verification Tests