For 1990-2009 cars

### Circuit/System 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.

### Reference Information

#### Schematic Reference

Antilock Brake System Schematics

#### Connector End View Reference

Component Connector End Views

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

#### Scan Tool Reference

Control Module References

### Circuit/System Testing

1. Install a scan tool.
2. Step on and off the brake pedal with enough force to simulate a hard braking condition and observe the Stop Lamp Switch parameter in the DRP/ABS/TCS data list.
3. Measure the distance that the brake pedal travels with a tape measure for the scan tool to read Applied.

⇒ | If distance that the brake pedal travels for the scan tool to read Applied DID NOT measure within the specified range, replace the Stop Lamp Switch.

### Repair Instructions

Stop Lamp Switch Replacement .