U180D

DTC U180D

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions Diagnostic Procedure Instructionsprovides an overview of each diagnostic category.

DTC Descriptor
DTC U180D 00
- Electronic Brake Control Module Chassis Expansion Communication Bus Off

Circuit/System Description

The chassis high speed GMLAN serial data circuits are serial data buses used to communicate information between the control modules. The chassis high speed GMLAN serial data circuits also connect directly to the data link connector (DLC) for programming purposes. If this serial data system is inoperative, the control modules will still communicate with the scan tool due to other serial data systems but not with each other.

Conditions for Running the DTC

* Supply voltage to the control modules are in the normal operating range.
* The vehicle power mode requires serial data communications.

Conditions for Setting the DTC

The control module setting the DTC has attempted to establish communications on the high speed GMLAN serial data circuits more than 3 times.

Action Taken When the DTC Sets

* The control module suspends all message transmission.
* The control module uses default values for all parameters received on the serial data circuits.
* The control module inhibits the setting of all other communication DTCs.

Conditions for Clearing the DTC

* A current DTC clears when the malfunction is no longer present.
* A history DTC clears when the module ignition cycle counter reaches the reset threshold, without a repeat of the malfunction.

Circuit/System Verification

Verify that U0077 is not set.

If the DTC is set, refer to DTC U0077 U0077.