Service Information

Volt

DTC U1795

Diagnostic Instructions

•	Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

•	Review Strategy Based Diagnosis for an overview of the diagnostic approach.

•	Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptor

DTC U1795 00: 14V Power Module Powertrain Expansion Communication Bus Off

The powertrain high-speed GMLAN serial data circuits are serial data buses used to communicate information between the control modules. The powertrain high-speed GMLAN serial data circuits also connect directly to the auxiliary data connector on passenger side. If this serial data system is inoperative, some 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 communication on the powertrain high-speed GMLAN serial data circuits more than 3 times.

Action Taken When the DTC Sets

•	The control module suspends all message transmission.

•	The MIL and battery indicators will illuminate, along with several DIC messages.

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 U0074 is not set.

⇒	If the DTC is set, refer to DTC U0074 .