Diagnostic Instructions
DTC Descriptor
DTC C0252 4A: VSES Sensor Uncorrelated Checksum Error
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 voltage is above 9.5 volts. |
Conditions for Setting the DTC
The EBCM reads the stored yaw sensor calibration values and compares them to the stored calibrations in the EBCM and detects a difference.
Action Taken When the DTC Sets
| • | The EBCM disables the VSES for the duration of the ignition cycle. |
| • | 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 clears the history DTC when a current DTC is not detected in 100 consecutive drive cycles. |
Diagnostic Aids
A loose or incorrectly mounted yaw lateral sensor
Reference Information
Schematic Reference
Antilock Brake System Schematics
Connector End View Reference
Component Connector End Views
Description and Operation Reference
ABS Description and Operation
Electrical Information Reference
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Verification
- Ignition ON, perform the steering position sensor calibration, clear DTCs and operate the vehicle within the conditions for setting.
- Verify that C0186, C0196 or C0460 is not set.
Repair Instructions
Perform the
Diagnostic Repair Verification after completing the diagnostic procedure.
