Antilock Brake System - Non-Hybrid Greater than/Equal to 3900 kg (8600 lb) GVW

DTC C0252

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

* Review Strategy Based Diagnosis Strategy Based Diagnosis for an overview of the diagnostic approach.

* Diagnostic Procedure Instructions Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptor

DTC C0252 00

-
VSES Sensor Uncorrelated

Circuit/System Description

The electronic brake control module (EBCM) controls the vehicle stability enhancement system (VSES) by monitoring the inputs from the yaw rate/lateral accelerometer sensor, wheel speed sensors and steering wheel angle sensor. All of the sensors need to correlate to the vehicle dynamics during the initial drive off in order to enable VSES. Normally this takes place within the first 15 minutes of driving.

Conditions for Running the DTC

* Ignition ON.

* Ignition voltage is greater than 10 volts

* The steer angle has been centered.

* The VSES system has not been initialized.

* 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 per second squared.

* Vehicle is moving.

Conditions for Setting the DTC

* Vehicle is driven greater than 8 km (5 mph) without VSES initialization

* The yaw rate error is greater then 10 degrees/second for 5 seconds, and the yaw has not changed and the lateral acceleration is less than 0.5 g.

Action Taken When the DTC Sets

* The EBCM disables the Antilock Brake System (ABS) /Traction Control System (TCS)/VSES for the duration of the ignition cycle.

* The ABS and VSES indicators illuminate.

* The driver information center displays the Service Traction Control and Stabilitrak message.

Conditions for Clearing the DTC

* The condition for the DTC is no longer present or the ignition is cycled.

* The EBCM automatically clears the history DTC when a current DTC is not detected in 100 consecutive drive cycles.

Diagnostic Aids

* The DTC C0252 can be set if the vehicle has been driven above 8 km (5 mph) on a rough or winding road prior to the VSES initialization with the brake pedal applied and while accelerating.

* Confirm that all tires are of the proper size and that all are matching brands. Check and adjust all tires to the stated cold air pressure as identified on the tire placard. If a mis-sized or non-matching brand tire is present, inform the customer that in order for the vehicle stability enhanced system to function normally, tires need to be a uniform size and rolling diameter.

* Driving off with constant steering wheel input or brake switch activation.

* An improperly mounted or loose combination yaw rate/lateral accelerometer sensor.

* Stuck brake switch.

* Improper wheel alignment or tire pull.

* An internal yaw rate/lateral accelerometer sensor failure.

* An EBCM internal failure.

Reference Information

Schematic Reference

Antilock Brake System Schematics [1][2]Antilock Brakes / Traction Control Systems

Connector End View Reference

Component Connector End Views 1-2 Shift Solenoid (SS) Valve (M30)

Description and Operation

ABS Description and Operation (Without JL4) Description and OperationABS Description and Operation (With JL4) Description and Operation

Electrical Information Reference

* Circuit Testing Circuit Testing

* Connector Repairs Connector Repairs

* Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections

* Wiring Repairs Wiring Repairs

Scan Tool Reference

Control Module References Control Module References for scan tool information

Circuit/System Verification

1. Ignition ON, verify that DTC C0035, C0040, C0045, or C0050 is not set.

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

2. Ignition ON, verify that DTC C0186, C0196, or C0710 is not set.

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

3. Ignition OFF, verify the yaw/lateral accelerometer sensor is mounted properly.

• If not mounted properly, refer to Vehicle Yaw Sensor with Vehicle Lateral Accelerometer Replacement Non-Hybrid Greater than/Equal to 3900 kg (8600 lb) GVW.

4. Ignition ON, clear DTC, test drive vehicle under normal driving conditions.

5. Verify DTC C0252 is not set

• If the DTC is set replace the EBCM.

Repair Instructions

Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.

* Vehicle Yaw Sensor with Vehicle Lateral Accelerometer Replacement Non-Hybrid Greater than/Equal to 3900 kg (8600 lb) GVW

* Control Module References Control Module References for EBCM replacement, programming and setup