U1508-IMPLAUSIBLE MESSAGE DATA LENGTH RECEIVED FROM ESM

For a complete wiring diagram Refer to Section 8W

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 DTCS PRESENT
 
ELECTRONIC SHIFT MODULE DTCS PRESENT
 
TRANSMISSION CONTROL MODULE
 


Always perform the NAG1 Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - NAG1 - STANDARD PROCEDURE)



Diagnostic Test

1.CHECK FOR FCM CAN BUS DTCS



Are there any FCM CAN BUS DTCs present?

Yes


No
  • Go To 2

2.ELECTRONIC SHIFT MODULE DTC'S PRESENT



Are there any ESM DTCs present?

Yes
  • Refer to Section 21 – AUTOMATIC TRANSMISSION NAG1 - SHIFTER DIAGNOSTICS and perform the appropriate diagnostic procedure.


No