ABS Description and Operation: Notes

This vehicle is equipped with a TRW EBC450 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.

Depending on options, the following vehicle performance enhancement systems are provided.

• Antilock brake system (ABS)
• Traction control
• Stability control
• Dynamic rear proportioning
• Hill start assist
• Cornering brake control
• Hydraulic brake assist
• Trailer stability 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 vales
  • Four dump valves
  • Two traction control/stability control supply valves
  • Two traction control/stability control isolation valves
  • Pressure sensor
  • High pressure attenuators
  • Low pressure accumulator
• Multi-axis acceleration sensor - The yaw rate, lateral acceleration and longitudinal acceleration sensors are combined into one multi-axis acceleration sensor, external to the EBCM. The EBCM receives serial data message inputs from the yaw rate, lateral acceleration and longitudinal acceleration sensor and activates stability control and hill start assist function depending on multi-axis acceleration sensor input.
• Steering angle sensor - The EBCM receives serial data message inputs from the steering angle sensor. 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 supplies 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.