2010 Cadillac Truck Escalade RWD V8-6.0L Hybrid Page 3279

2010 Cadillac Truck Escalade RWD V8-6.0L Hybrid Page 3279

* Front Side Door Window Regulator Motor Replacement (See: Windows and Glass/Windows/Service and Repair/Front Side Door Window

Regulator Motor Replacement)

* Rear Side Door Window Regulator Motor Replacement (See: Windows and Glass/Windows/Service and Repair/Rear Side Door Window

Regulator Motor Replacement)

* Control Module References (See: Testing and Inspection/Programming and Relearning) for window, and door lock switches (door

modules), window regulator motors, or electronic compass module replacement, setup, and programming

U1812

DTC U1812

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic System

Check - Vehicle) prior to using this diagnostic procedure.

* Review Strategy Based Diagnosis (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Strategy Based Diagnosis) for an

overview of the diagnostic approach.

* Diagnostic Procedure Instructions (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic Procedure

Instructions) provides an overview of each diagnostic category.

DTC Descriptors

DTC U1812 00

- Battery Energy Control Module Bus B High Speed Communication Enable Circuit Low

Diagnostic Fault Information

Circuit/System Description

Modules connected to the high and low speed GMLAN serial data circuits monitor for serial data communications during normal vehicle operation.

Operating information and commands are exchanged among the modules. The modules have prerecorded information about what messages are

needed to be exchanged on the serial data circuits, for each virtual network. The messages are supervised and some periodic messages are used by

the receiver module as an availability indication of the transmitter module. Each message contains the identification number of the transmitter

module.

The serial data gateway (SDG) module translates serial data messages between the high speed GMLAN serial data bus, the low speed GMLAN

serial data bus, and the high speed hybrid GMLAN serial data bus. Messages between the drive motor generator battery control module and the

other hybrid system control modules must pass thru the SDG module. The wake up circuit sends a voltage from the SDG module to the drive motor

generator battery control module to initiate certain module functions. DTC U1812 is set by the drive motor generator battery control module, but is

stored in and reported by the hybrid powertrain control module (HPCM).

Conditions for Running the DTC

* The system voltage is between 9-16 volts.

* The vehicle power mode master requires serial data communication to occur.

Conditions for Setting the DTC

The drive motor generator battery control module did not receive voltage from the SDG module on the wake up signal circuit.

Action Taken When the DTC Sets

* The driver information center (DIC) displays the message Service Hybrid System.

* Multiple DTCs may set depending on the fault location and when the fault occurred.

Conditions for Clearing the DTC

* A current DTC clears when the malfunction is no longer present.