2010 Cadillac Truck Escalade EXT AWD V8-6.2L Page 2997
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. Only the modules using high speed GMLAN serial data are connected to the
enable or wake up circuits. Refer to the schematics to determine which modules activate and are activated using the enable or wake up circuits.
DTC U1888 is set by the drive motor generator battery control module, but is stored in and reported by the hybrid powertrain control modul
Conditions for Running the DTC
* The system voltage is between 9-16 volts.
* The vehicle power mode master requires serial data communication to occur fro this specific module.
Conditions for Setting the DTC
A supervised periodic message that includes the transmitter module availability has not been received.
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.
* The vehicle will not start or run because the 300 volt battery contactors are OPEN.
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 of 50, without a repeat of the malfunction.
Circuit/System Verification
With a scan tool, ensure the following DTCs are not present in the modules as follows:
BCM
U2099
PSCM
U0146
SDG module
* SDG module - U0111
* SDG module - B1453
If the DTC is set, refer to Diagnostic Trouble Code (DTC) List - Vehicle (See: Diagnostic Trouble Code Descriptions/Diagnostic Trouble Code
(DTC) List - Vehicle).
U2099
DTC U2099
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic System
Check - Vehicle) prior to using the 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 Descriptor
DTC U2099 00
- High Speed Communication Enable Circuit
Diagnostic Fault Information
