For 1990-2009 cars

### 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's yaw motion by applying differential braking to the left or right front wheel.

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
Schematic Reference: Antilock Brake System Schematics
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | Go to Diagnostic System Check - Vehicle
2 |

1. With a scan tool, observe the Stop Lamp Switch parameter in the DRP/ABS/TCS data list.
2. Step on and off the brake pedal with enough force to simulate a hard braking condition. As the brake pedal is pressed and released, the scan tool should read Applied and Released.
3. Use a tape measure in order to measure the distance that the brake pedal travels for the scan tool to read Applied.

Does the distance measure within the specified range?

2.5-3.3 cm (1.0-1.3 in )

Go to Testing for Intermittent Conditions and Poor Connections

Go to Step 3

3 | Replace the brake pedal position sensor. Refer to Brake Pedal Position Sensor Replacement . Did you complete the replacement? | -- | Go to Step 4 | --
4 | Operate the system in order to verify the repair. Did you correct the condition? | -- | System OK | Go to Step 2