2010 Cadillac Truck Escalade RWD V8-6.2L Page 2861
* PTLAN + APM terminal 5 and EBCM terminal 33
* PTLAN - APM terminal 1 and EBCM terminal 21
瀚慖f greater than the specified range, test the circuit for an open/high resistance.
3. Ignition OFF, disconnect harness connector X1 of the SDGM.
4. Test for less than 1.0 ohm between the EBCM and the SDGM on the following circuit terminals.
* PTLAN + EBCM terminal 34 and SDGM terminal 13
* PTLAN - EBCM terminal 22 and SDGM terminal 11
瀚慖f greater than the specified range, test the circuit for an open/high resistance.
5. If the circuits test normal, replace the SDGM.
Repair Instructions
Perform the Diagnostic Repair Verification (See: Verification Tests) after completing the diagnostic procedure.
* GMLAN Wiring Repairs (See: Testing and Inspection/Component Tests and General Diagnostics/General Electrical Diagnostic
Procedures/Wiring Repairs/GMLAN Wiring Repairs)
* Control Module References (See: Testing and Inspection/Programming and Relearning) for module replacement, setup, and programming
U1820
DTC U1820
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 Descriptor
DTC U1820 00
- Lost Communication with Brake System Control Module on Bus B
Diagnostic Fault Information
Circuit/System Description
Modules connected to the PTLAN 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 also, 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.
Conditions for Running the DTC
* The system voltage is between 9-16 volts.
* The vehicle power mode master requires serial data communication to occur for this specific module.
