2010 Cadillac Truck Escalade EXT AWD V8-6.2L Page 2905
* Some control modules may not have internal protection for specific control circuits and may open a B+ or ignition fuse. If a fuse is open and
the B+ or ignition circuit is not shorted to ground, ensure none of the control circuits are shorted to ground before replacing the control
module.
* This diagnostic can be used for any control module that is not communicating, regardless of the type of serial data circuit it is connected to,
providing the vehicle is equipped with the control module.
Reference Information
Schematic Reference
* Data Communication Schematics (See: Powertrain Management/Computers and Control Systems/Information Bus/Diagrams/Electrical
Diagrams)
* Control Module References (See: Testing and Inspection/Programming and Relearning)
Connector End View Reference
Component Connector End Views (See: Diagrams/Connector Views)
Description and Operation
Data Link Communications Description and Operation (See: Powertrain Management/Computers and Control Systems/Information
Bus/Description and Operation)
Electrical Information Reference
* Circuit Testing (See: Testing and Inspection/Component Tests and General Diagnostics/General Electrical Diagnostic Procedures/Circuit
Testing/Circuit Testing)
* Connector Repairs (See: Testing and Inspection/Component Tests and General Diagnostics/General Electrical Diagnostic
Procedures/Connector Repairs/Connector Repairs)
* Testing for Intermittent Conditions and Poor Connections (See: Testing and Inspection/Component Tests and General Diagnostics/General
Electrical Diagnostic Procedures/Circuit Testing/Testing for Intermittent Conditions and Poor Connections)
* Wiring Repairs (See: Testing and Inspection/Component Tests and General Diagnostics/General Electrical Diagnostic Procedures/Wiring
Repairs/Wiring Repairs)
Scan Tool Reference
Control Module References (See: Testing and Inspection/Programming and Relearning) for scan tool information
Circuit/System Verification
Verify that DTC U1814, U2099, B1428, B1370, B1380, B1440, or B1441 is not set.
If any of the DTCs are set, refer to Diagnostic Trouble Code (DTC) List - Vehicle (See: Diagnostic Trouble Code Descriptions/Diagnostic
Trouble Code (DTC) List - Vehicle).
Circuit/System Testing
Note: Use the schematic to identify the following:
* Control modules the vehicle is equipped with
* Control module locations on the low and high speed GMLAN serial data circuits
* The control modules B+, ignition, ground, communication enable and serial data circuit terminals
1. Determine the control module that is not communicating. Refer to Control Module U Code List (See: Diagnostic Trouble Code
Descriptions/Control Module U Code List).
2. Ignition OFF, disconnect the harness connector of the control module that is not communicating.
3. Test for less than 10 ohm between each ground circuit terminal and ground.
瀚慖f greater than the specified range, test the ground circuit for an open/high resistance.
4. If equipped, verify that a test lamp illuminates between each B+ circuit terminal and ground.
瀚慖f the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. If the circuit fuse is open, test the
control circuits of the control module for a short to ground. If the circuits test normal, replace the control module.
5. If equipped, ignition ON, verify that a test lamp illuminates between each ignition circuit terminal and ground.
瀚慖f the test lamp does not illuminate, test the ignition circuit for a short to ground or an open/high resistance. If the circuit fuse is open, test
the control circuits of the control module for a short to ground. If the circuits test normal, replace the control module.
Note: Only the high speed GMLAN modules have a serial data communication enable circuit OR an accessory wakeup serial data circuit,
and the BCM is the output for these circuits. Refer to the control module schematics to identify which control modules have these circuits.
