* GMLAN Wiring Repairs (See: Testing and Inspection/Component Tests and General Diagnostics/General Electrical Diagnostic
Procedures/Wiring Repairs/GMLAN Wiring Repairs)
* ABS Description and Operation (See: Brakes and Traction Control/Antilock Brakes / Traction Control Systems/Description and
Operation/ABS Description and Operation) for the ABS - Hybrid
* Vehicle Yaw Sensor with Vehicle Lateral Accelerometer Replacement (See: Brakes and Traction Control/Antilock Brakes / Traction
Control Systems/Yaw Rate Sensor/Service and Repair/Less than 3900 kg (8600 lb) GVW) for the ABS - Non-Hybrid Less than 3900 kg
(8600 lb) GVW
* Vehicle Yaw Sensor with Vehicle Lateral Accelerometer Replacement (See: Brakes and Traction Control/Antilock Brakes / Traction
Control Systems/Yaw Rate Sensor/Service and Repair/Less than 3900 kg (8600 lb) GVW) for the ABS - Non-Hybrid Greater than/Equal to
3900 kg (8600 lb) GVW
* Control Module References (See: Testing and Inspection/Programming and Relearning) for module replacement, setup, and programming
U2123
DTC U2105-U2199
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 U2142 00
- Lost Communication With Yaw Rate Sensor (YRS)
Circuit/System Description
Modules connected to the CAN bus 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. 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.
The electronic brake control module (EBCM) activates the other modules connected to the CAN serial data circuits by applying voltage when the
ignition key is in ACC, ON or START. The EBCM, Yaw Rate and Lateral Acceleration Sensor are the only modules connected to the CAN bus
serial data circuits. For more information on CAN bus serial data refer to Data Link Communications Description and Operation (See: Powertrain
Management/Computers and Control Systems/Information Bus/Description and Operation).
Conditions for Running the DTC
* The system voltage is between 9-16 volts.
* The vehicle power mode master requires serial data communication to occur.
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 vehicle stability enhancement system (VSES), if equipped, and traction control system (TCS) will not function.
* System OFF lamps will illuminate for these systems.
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
* Sometimes, while diagnosing a specific customer concern or after a repair, you may notice a history U-code present. However, there is no
associated "current" or "active" status. Loss-of- communication U-codes such as these can set for a variety of reasons. Many times, they are
transparent to the vehicle operator and technician, and/or have no associated symptoms. Eventually, they will erase themselves automatically
after a number of fault-free ignition cycles. This condition would most likely be attributed to one of these scenarios:
