door module.
5. If all circuits test normal, replace the window motor.
Repair Instructions
Note: Each window regulator motor or front window and door lock switch, if replaced needs to be setup for proper operation.
Perform the Diagnostic Repair Verification (See: Verification Tests) after completing the diagnostic procedure.
* 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.
