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 Instructions provides an overview of each diagnostic category.

DTC Descriptor

DTC U180D
- Electronic Brake Control Module Chassis Expansion CAN Bus Off

For symptom byte information, refer to Symptom Byte List Symptom Byte List.

Circuit/System Description

The chassis high speed GMLAN serial data circuits are serial data buses used to communicate information between the devices. 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 devices 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 devices are in the normal operating range.

* The vehicle power mode requires serial data communications.

Conditions for Setting the DTC

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

Action Taken When the DTC Sets

* The device suspends all message transmission.

* The device uses default values for all parameters received on the serial data circuits.

* The device 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 device ignition cycle counter reaches the reset threshold, without a repeat of the malfunction.

Circuit/System Verification

1. Vehicle in Service Mode.

2. Verify DTC U180D is not set.

• If DTC U180D is set
Refer to DTC U0077 U0077.

• If DTC U180D is not set

3. All OK