C0252

DTC C0252

Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (Initial Inspection and Diagnostic Overview) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Initial Inspection and Diagnostic Overview) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Initial Inspection and Diagnostic Overview) provides an overview of each diagnostic category.

DTC Descriptor
DTC C0252 00
- VSES Sensor Uncorrelated

Circuit/System Description
The vehicle stability enhancement system (VSES) is activated by the electronic brake control module (EBCM) and calculates the desired yaw rate and comparing it to the actual yaw rate input. The desired yaw rate is calculated from measured steering wheel position, vehicle speed, and lateral acceleration. The difference between the desired yaw rate and actual yaw rate is the yaw rate error, which is a measurement of oversteer or understeer. If the yaw rate error becomes to large, the EBCM will attempt to correct the vehicle's yaw motion by applying differential braking to the left or right front wheel.

The amount of differential braking applied to the left or right front wheel is based on both the yaw rate error and side slip rate error. The side slip rate error is a function of the lateral acceleration minus the product of the yaw rate and vehicle speed. The yaw rate error and side slip rate error are combined to produce the total delta velocity error. When the delta velocity error becomes too large and the VSES system activates, the drivers steering inputs combined with the differential braking will attempt to bring the delta velocity error toward 0. The VSES activations generally occur during aggressive driving, in the turns or bumpy roads with out much use of the accelerator pedal. When braking during VSES activation, the brake pedal will feel different than the antilock brake system (ABS) pedal pulsation. The brake pedal pulsates at a higher frequency during VSES activation.

Conditions for Running the DTC
* Ignition is ON.
* The ignition voltage is above 9.5 volts.

Conditions for Setting the DTC
There is an incorrect checksum stored in the EEPROM area where the dynamic sensor offsets are saved.

Action Taken When the DTC Sets
* The VSES is disabled.
* A DIC message and/or a warning indicator may be displayed.

Conditions for Clearing the DTC
* The condition for the DTC is no longer present.
* The EBCM automatically clears the history DTC when a current DTC is not detected in 50 consecutive drive cycles.

Diagnostic Aids
* Improper steering alignment or tire pull.
* A loose or incorrectly mounted yaw lateral sensor.
* An internal yaw rate/lateral accelerometer failure.
* An EBCM internal failure.

Reference Information
Schematic Reference

Antilock Brake System Schematics (Electrical Diagrams)
Connector End View Reference

Component Connector End Views (Connector Views)
Description and Operation Reference

ABS Description and Operation (Description and Operation)
Electrical Information Reference

* Circuit Testing (Component Tests and General Diagnostics)
* Testing for Intermittent Conditions and Poor Connections (Component Tests and General Diagnostics)
* Wiring Repairs (Component Tests and General Diagnostics)
* Connector Repairs (Component Tests and General Diagnostics)

Scan Tool Reference
Control Module References (Programming and Relearning) for scan tool information

Circuit/System Verification
1. Clear DTCs and operate the vehicle within the conditions for setting the DTC.
2. Verify that DTC U1651, C0186, C0196, C0292 or C0710 is not set.

--> If any of the DTCs are set, refer to Diagnostic Trouble Code (DTC) List - Vehicle (Diagnostic Trouble Code Descriptions).

3. Verify the yaw/lateral accelerometer sensor is mounted properly.

--> If not mounted properly, refer to Vehicle Longitudinal Accelerometer Replacement. Service and Repair

4. Clear DTC, test drive vehicle under normal driving conditions.

--> If the DTC is set replace the yaw/lateral accelerometer sensor. If the DTC resets, replace the EBCM.

Repair Instructions
Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.
* Vehicle Longitudinal Accelerometer Replacement ()
* Control Module References (Programming and Relearning) for EBCM replacement, setup and programming