C0252
DTC C0252
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Initial Inspection and Diagnostic Overview
* Review Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions provides an overview of each diagnostic category.
DTC Descriptor
DTC C0252 00
- Steering Wheel Position Sensor Uncorrelated
Diagnostic Fault Information
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
* The steer angle has been centered.
* The VSES is active.
* The direction (understeer or oversteer) of the yaw rate error has not changed.
* The centered lateral acceleration value is less than 0.5 g.
* The yaw rate error is less than 6 degrees/second.
* The side slip error is greater than 1.8 meters/second*second.
Conditions for Setting the DTC
One of the following conditions exists:
* The yaw rate error is greater than 10 degrees/second with the vehicle speed less than 60 Km/h (37 mph) and the acceleration pedal is pressed more than 25 percent of the pedal travel range for 1 second during the VSES activation.
* With the yaw rate less than 8 degrees/second, the side slip error is greater than 4.9 meters/second for 5 seconds.
Action Taken When the DTC Sets
One or more of the following actions may occur:
* The Antilock Brake System (ABS Vehicle Stability Enhancement System (VSES) are disabled.
* TCS is degraded.
* The ABS/TCS indicators turn ON.
* The red BRAKE Warning indicator turns ON.
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 100 consecutive drive cycles.
Diagnostic Aids
The following conditions can cause this concern:
* Improper steering alignment
* An open, a short to ground, or a short to voltage
* An internal lateral accelerometer failure
* An EBCM internal failure
Reference Information
Schematic Reference
Antilock Brake System Schematics
Connector End View Reference
Antilock Brake System Connector End Views
Electrical Information Reference
* Circuit Testing
* Connector Repairs
* Testing for Intermittent Conditions and Poor Connections
* Wiring Repairs
Scan Tool Reference
Scan Tool Data List for EBCM
Circuit/System Verification
Clear DTC, test drive vehicle under normal driving conditions.
Verify DTC resets.
Circuit/System Testing
1. Ignition OFF, disconnect the yaw rate sensor/lateral accelerometer and the steering wheel position sensor connectors.
2. Ignition ON, measure for 4.8-5.2 volts at each 5-volt reference circuits and ground.
^ If over 5.2 volts, test each 5-volt reference circuit for a short to voltage. If the circuits tests normal, replace the EBCM.
^ If under 4.8 volts, test each 5-volt reference circuit for short to ground. If the circuits tests normal, replace the EBCM.
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure. Verification Tests
Control Module References for EBCM refer to programing and relearning Programming and Relearning
Repair Verification
Diagnostic Repair Verification