Under normal operating conditions the brake system will operate using the following conventional braking:
An ABS stop occurs when the Electronic Brake Control Module (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.
The Antilock Brake System (ABS) perform a series of test to ABS components for proper operation and readiness. The initialization starts when the ignition switch is turned from LOCK to ON position. The Electronic Brake Control Module (EBCM) turns ON the ABS warning indicator for 3 seconds. When the ABS indicator turns OFF a slight mechanical noise can be heard. This condition is normal. This noise comes from the brake pressure modulator valve assembly as the EBCM tests solenoid valves and the pump motor.
When stepping on the brake pedal when turning the ignition switch to the On position the EBCM completes the initialization process after you release the brake pedal. Upon brake pedal release the EBCM checks the solenoid valves and the pump motor. A slight mechanical noise is heard.
A slight pulsation may be felt when stepping on the brake pedal while the EBCM is testing the solenoid valves and the pump motor. This condition is considered normal brake pedal feedback.
The Antilock Brake System (ABS) uses an ABS warning indicator located in the instrument panel gage cluster.
Using the compact spare supplied with the vehicle will not affect the operation of the Antilock Brake System (ABS). The ABS compensates for the smaller compact spare tire. However the driver will notice increased stopping distances due to the reduced size of the compact spare tire.
The tire size is important for proper performance of the Antilock Brake System (ABS). When replacing the original tires use the following replacement guidelines:
Replace the tires in axle sets and only with tires of the same Tire Performance Criteria (TPC) specification number. Use of any other tire size or type may seriously affect the ABS operation.
