2010 Cadillac CTS Sedan AWD V6-3.6L Page 2070
1. Use the DTC Descriptor and Diagnostic Aids above, determine the module that is not communicating that should be tested.
2. Ignition OFF, disconnect the harness connector at the Steering Wheel Position Sensor.
3. Ignition ON, verify that a test lamp illuminates between the Steering Wheel Position Sensor voltage (12-volt ref) circuit terminal 5 and
ground.
瀚慖f the test lamp does not illuminate, test the circuit for a short to ground, or open/high resistance. If the circuit tests normal, replace the
Steering Wheel Position Sensor.
4. Ignition OFF, test for less than 5 ohms between the Steering Wheel Position Sensor low reference circuit terminal 6 and ground.
瀚慖f greater than the specified value, test the ground circuit for an open/high resistance. If the circuit tests normal, replace the Steering
Wheel Position Sensor.
5. Test for less than 1 ohm in the CAN bus serial data circuits between the Steering Wheel Position Sensor terminal 2 and 3, and the Yaw Rate
Sensor terminal 5 and 4.
瀚慖f greater than 1 ohm, test the serial data circuits for open/high resistance.
6. If all circuits test normal, replace the Steering Wheel Position Sensor.
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/Wiring Repairs/GMLAN Wiring Repairs)
* Vehicle Yaw Sensor with Vehicle Lateral Accelerometer Replacement (See: Brakes and Traction Control/Antilock Brakes / Traction
Control Systems/Yaw Rate Sensor/Service and Repair)
* Control Module References (See: Testing and Inspection/Programming and Relearning) for module replacement, setup, and programming
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 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 U2099 00
- High Speed Communication Enable Circuit
Diagnostic Fault Information
Circuit/System Description
The body control module (BCM) applies voltage to the high speed GMLAN serial data wake up circuit, when the ignition key is in ACC, ON or
START to enable several modules for bus communication.
Depending on option content, modules that may receive the signal are as follows:
* Electronic brake control module (EBCM)
* Electronic suspension control (ESC) module - (FE1) (F55)
Conditions for Running the DTC
* The system voltage is between 9-16 volts.
