ABS Description & Operation: Notes
WARNING: This page is about a different car, the 2008 GMC Yukon and 2008 Chevrolet Tahoe. However, it is still accessible from the selected car via links, so may be relevant.
This vehicle is equipped with an EBC 440 ABS/EBD/VSES/SCB module.
This module provides the following vehicle performance enhancement systems:
- Antilock Brake System (ABS)
- Electronic Brake Distribution (EBD)
- Slip Control Boost (SCB)
- Master Cylinder Assembly (MC)
The following components are involved in the operation of the above systems:
- Electronic brake control module (EBCM)-The EBCM controls the system functions and detects failures.
The EBCM contains the following components:
- System relay-The system relay is internal to the EBCM. The system relay is energized when the ignition is ON. The system relay supplies battery positive voltage to the valve solenoids and to the ABS pump motor. This voltage is referred to as system voltage.
- Solenoids-The solenoids are commanded ON and OFF by the EBCM to operate the appropriate valves in the brake pressure modulator valve (BPMV).
- Brake pressure modulator valve (BPMV)-The BPMV uses a 4-circuit configuration to control hydraulic pressure to each front wheel independently, and to the rear braking system
The BPMV contains the following components:
- ABS pump motor and pump
- Isolation valves
- Dump valves
- High pressure accumulator
- Electronic hydraulic control unit
- Wheel speed sensors (WSS)-EBCM sends a 12-volt reference voltage signal to each front wheel speed sensor. As the wheel spins, the wheel speed sensor produces a square wave DC signal voltage. The wheel speed sensor increases the signal frequency as the wheel speed increases, but does not increase the signal amplitude.