2010 Cadillac Truck Escalade EXT AWD V8-6.2L Page 2986
* 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 Descriptor
DTC U1862 00
- Battery Energy Control Module Lost Communication with Serial Data Gateway Module
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 enable signal circuit is energized by the body control module (BCM) to activate multiple modules when the BCM determines that
communication is required. Some modules may still become active due to their own ignition voltage source if the enable circuit is not functional.
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. DTC U1862 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 from the drive motor generator battery control module via the
SDG module.
Conditions for Setting the DTC
A supervised periodic message that includes the SDG module availability has not been received by the drive motor generator battery control
module.
Action Taken When the DTC Sets
* The charging system will not operate properly and the vehicle battery will discharge as the vehicle is driven.
* 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
