GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Buick 🢒 2006 🢒 Allure 🢒 DTC 🢒 DTC C0252

Circuit Description

The vehicle stability enhancement system (VSES) is activated by the electronic brake control module (EBCM) calculating 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 too large, the EBCM will attempt to correct the vehicle yaw motion by applying differential braking to the left or right wheels.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC C0252 Vehicle Stability Enhancement System (VSES) Sensors Uncorrelated

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 lateral acceleration is less than 0.5 grams.

Conditions for Setting the DTC

One of the following conditions occur:

    • The VSES is engaged for 10 seconds with the yaw rate error always in either understeer or oversteer. Under this condition, this DTC will set by itself.
    • The yaw rate error is greater than 10 degrees/second for 5 seconds.

Action Taken When the DTC Sets

If equipped, the following actions occur:

    • The EBCM disables the antilock brake system (ABS)/traction control system (TCS)/VSES and for the duration of the ignition cycle.
    • A malfunction DTC will set.
    • The ABS indicator turns ON.
    • The Stability Off indicator turns ON.

Conditions for Clearing the DTC
    • The condition for the DTC is no longer present, the DTC is not current, and you used the scan tool Clear DTC function.
    • The EBCM automatically clears the history DTC when a current DTC is not detected in 100 consecutive drive cycles.

Diagnostic Aids
    • During diagnosis, park the vehicle on a level surface.
    • Inspect the vehicle for proper alignment. The car should not pull in either direction while driving straight on a level surface.
    • Find out from the customer the conditions under which the DTC was set. This information will help to duplicate the failure.
    • The Snapshot function on the scan tool can help find an intermittent DTC.

Test Description

The numbers below refer to the step numbers on the diagnostic table.

  1. This checks to see if DTC C0252 is set.

    2.

  2. This step checks to see if the DTC C0252 resets.

    3.

  3. This step checks to see if VSES data list parameters are correct.

    4.

  4. This step checks the components harness connectors for poor connections.

Step

Action

Yes

No

Schematic Reference: Antilock Brake System Schematics

Connector End View Reference: Antilock Brake System Connector End Views

1

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle

2

  1. Turn OFF the ignition.
  2. Install a scan tool.
  3. Turn ON the ignition, with the engine OFF.
  4. Select the ABS DTC display function.

Does the scan tool display any DTC other than DTC C0252?

Go to Diagnostic Trouble Code (DTC) List - Vehicle

Go to Step 3

3

  1. Use the scan tool in order to clear the DTC.
  2. Perform the Diagnostic Test Drive .
  3. Use the scan tool to select the ABS DTC display function.

Does the DTC reset?

Go to Step 4

Go to Diagnostic Aids

4

  1. Use the scan tool to select the VSES data list.
  2. Compare data to the typical values located in the electronic brake control module (EBCM) scan tool data list under Vehicle Stability Enhancement System (VSES) Data List. Refer to Scan Tool Data List .

Are all parameters correct?

Go to Step 5

Go to Testing for Intermittent Conditions and Poor Connections

5

Check the wiring harness connectors for the following:

    • EBCM
    • Brake pressure sensor
    • Steering angle sensor
    • Yaw/lateral accelerometer sensor
    • LF wheel speed sensor (WSS)
    • RF WSS
    • RF WSS
    • RR WSS

Did you find and correct the condition?

Go to Step 6

Go to Testing for Intermittent Conditions and Poor Connections

6
  1. Use the scan tool in order to clear the DTCs.
  2. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.

Does the DTC reset?

Go to Step 2

System OK