U180A

DTC U180A

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 U180A 00
- Electric A/C Compressor Control Module High Speed Communication Bus Off

Circuit/System Description

The high speed GMLAN serial data circuits are serial data buses used to communicate information between the control modules. The high speed GMLAN serial data circuits also connect directly to the data link connector (DLC) for programming purposes.

Conditions for Running the DTC

* The system voltage is greater than 10.25 V.
* 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

DTC U180A is a type B DTC.

Conditions for Clearing the DTC

DTC U180A is a type B DTC.

Circuit/System Verification

Diagnosis is accomplished using the symptom Scan Tool Does Not Communicate with High Speed GMLAN Device Scan Tool Does Not Communicate with High Speed GMLAN Device.