2010 Cadillac CTS Sedan AWD V6-3.0L Page 2054
* The BCM attempts to enable the modules connected to the high speed GMLAN serial data wake up circuit.
Conditions for Setting the DTC
The BCM senses a short to ground on the high speed GMLAN serial data wake up circuit.
Action Taken When the DTC Sets
* The output command is turned off while the malfunction is present.
* The modules use a default value for the missing parameters.
* The module(s) is never signaled, therefore the specific subsystem(s) will not function.
* The vehicle will not start while the circuit is shorted to ground.
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.
Diagnostic Aids
* Use the DMM MIN/MAX function to capture/locate intermittent conditions.
* Short to ground will also set multiple history no communication codes for GMLAN high speed modules.
Reference Information
Schematic Reference
* Body Control System Schematics (See: Body and Frame/Body Control Systems/Diagrams/Electrical Diagrams)
* Data Communication Schematics (See: Powertrain Management/Computers and Control Systems/Information Bus/Diagrams/Electrical
Diagrams)
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/Circuit Testing/Circuit Testing)
* Connector Repairs (See: Testing and Inspection/Component Tests and General Diagnostics/Connector Repairs/Connector Repairs)
* Testing for Intermittent Conditions and Poor Connections (See: Testing and Inspection/Component Tests and General Diagnostics/Circuit
Testing/Testing for Intermittent Conditions and Poor Connections)
* Wiring Repairs (See: Testing and Inspection/Component Tests and General Diagnostics/Wiring Repairs/Wiring Repairs)
Circuit/System Testing
1. With the ignition OFF, disconnect the harness connector at the EBCM and ESC module one at a time. After each disconnect, clear the DTC,
cycle the ignition key 3 times, then retest for the DTC. DTC U2099 should reset.
瀚慖f the DTC does not reset, replace the last module disconnected.
2. Ignition OFF, disconnect the harness connector X3 of the BCM.
3. With all modules disconnected, test for infinite resistance between the high speed GMLAN serial data wake up circuit and ground.
瀚慖f less than specified, repair the wake up circuit for a short to ground.
4. If all circuits test normal, replace the BCM.
Repair Instructions
Perform the Diagnostic Repair Verification (See: Verification Tests) after completing the diagnostic procedure.
Control Module References (See: Testing and Inspection/Programming and Relearning) for module replacement, setup, and programming
