Anti-Lock Braking Mode: Notes

WARNING: This page is about a different car, the 2004 Pontiac Vibe. However, it is still accessible from the selected car via links, so may be relevant.

An ABS stop occurs when the EBCM determines that one or more wheels are about to lose traction during braking. During an ABS stop the EBCM commands hydraulic pressure reduction at the wheel brake that is about to lose traction. The EBCM activates the solenoid valve for the affected wheel brake hydraulic channel. The solenoid valve triggers the adjoining flow control valve which directs hydraulic pressure into a buffer chamber. The result is a reduction in hydraulic pressure at the wheel brake thus reducing the tendency of wheel slip.

When the wheel is no longer slipping the EBCM deactivates the solenoid valve. This action allows the flow control valve to increase hydraulic pressure at the wheel brake.

This operation continues for all wheels until the wheels are no longer slipping for the duration of the stop. Although the ABS can modulate hydraulic pressure to each wheel brake it cannot increase hydraulic pressure above the amount which is transmitted by the master cylinder during braking.

The driver will notice a slight brake pedal pulsation during an ABS stop. This sensation is related to ABS component operation feedback and is considered normal.