U1041 GMC Electronic Brake Control Module Missing Data

Modules connected to the class 2 serial data circuit monitor for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the modules. When a module receives a message for a critical operating parameter, the module records the identification number of the module which sent the message for state of health monitoring/node alive messages. A critical operating parameter is one which, when not received, requires that the module use a default value for that parameter. Once an identification number is learned by a module, it will monitor for that modules node alive message. Each module on the class 2 serial data circuit is required to send a Node Alive message every 2 seconds . When no message is detected from a learned identification number for 5 seconds , a DTC U1XXX GMC. XXX is equal to the 3 digit identification number of the module. Contol Module ID = BCM

The Control Module ID Number list provides a method for determining which module is not communicating. A module with an internal class 2 serial data circuit malfunction or which loses power during the current ignition cycle would have a Lost Communication DTC set by other modules.

Powertrain Control Module (PCM) 016

Hybrid Control Module (CHM) 023

Transmission Control Module (TCM) 024

Transfer Case Shift Control Module (TCSCM) 026

Electronic Brake and Traction Control Module (EBTCM) 040

Electronic Brake Control Module (EBCM) 041

Sensing and Diagnostic Module (SDM) 088

Instrument Panel Cluster (IPC) 096