ABS Description and Operation: Notes
This vehicle is equipped with a Bosch ABS 8 brake system. The electronic brake control module (EBCM) and the brake pressure modulator valve assembly are serviced separately. The brake pressure modulator valve assembly uses a 4 circuit configuration to control hydraulic pressure to each wheel independently.
The following vehicle performance enhancement systems are provided.
- Antilock brake system (ABS)
- Traction control
- Stability control
- Dynamic rear proportioning
- Hydraulic brake assist
The following components are involved in the operation of the above systems:
- EBCM - The EBCM controls the system functions and detects failures. It supplies voltage to the solenoid valves and pump motor.
- Brake pressure modulator valve assembly - The brake pressure modulator valve assembly contains the following components:
- Hydraulic pump with pump motor
- Four isolation solenoid vales
- Four dump solenoid valves
- Two traction control/stability control prime solenoid valves
- Two traction control/stability control isolation solenoid valves
- Pressure sensor
- High pressure attenuator
- Low pressure accumulator
- Multi-axis acceleration sensor - The yaw rate and lateral acceleration sensors are combined into one multi-axis acceleration sensor module, external to the EBCM. The EBCM receives serial data message inputs from the yaw rate and lateral acceleration sensor and activates stability control depending on multi-axis acceleration sensor module input.
- Steering angle sensor - The EBCM receives serial data message inputs from the steering angle sensor module. The steering angle sensor signal is used to calculate the desired yaw rate.
- Traction control switch - Traction control and stability control are manually disabled or enabled by pressing the traction control switch.
- Wheel speed sensors - The EBCM sends a 12 V reference voltage to each wheel speed sensor. As the wheel spins, the wheel speed sensor produces an alternating current square wave signal. The EBCM uses the frequency of the square wave signal to calculate the wheel speed.