Ch.45: Anti-Lock brakes, traction control, and stability control systems

ABS control module

An ECM that uses wheel speed sensor inputs to control the operation of the electro-hydraulic modulator

ABS hydraulic modulator

A component that regulates the fluid pressure applied to each wheel brake assembly during periods of hard braking. It is also referred to as an ABS modulator or ABS hydraulic control unit

ABS warning light

An amber indicator lamp mounted in the instrument cluster. It illuminates when there is a problem with the anti-lock brake system.

anti-lock brake system (ABS)

A computer-controlled system that is part of the base brake system. The system cycles the brakes on and off to prevent wheel lockup and skidding.

brake accumulator

A chamber in an ABS modulator used for storing extra fluid under high pressure.

brake fluid pump

A high-pressure pump operated by a small electric motor; it provides brake fluid pressure for an ABS system

brake pressure sensor

A sensor that measures the hydraulic pressure in an anti-lock brake system (ABS).

brake pressure switch

A switching type sensor that closes when a certain brake pressure level is reached.

brake solenoid valve block

An hydraulic device that contains coil-operated valves. The valves control brake fluid flow to each wheel brake cylinder.

electronic stability control (ESC) system

A system that electronically links the steering, suspension, braking, and traction control systems together to prevent a loss of vehicle control and skidding when cornering at high speed.

hydraulic pressure modulation

Refers to the electro-hydraulic unit’s ability to rapidly cycle pressure to the wheel cylinders or calipers on and off, preventing wheel lockup and skidding.

integrated ABS

A system that combines the power booster, master cylinder, and modulator units into one assembly. All these units are mounted together.

lateral acceleration sensor

A stability control system sensor that measures how much side force is generated by a turn.

master cylinder-booster assembly

A conventional master cylinder with power assist for operating brakes under normal conditions.

master cylinder-booster assembly

A conventional master cylinder with power assist for operating brakes under normal conditions.

sensor trigger wheel

A toothed ring that rotates with the wheel hub. As each tooth passes the sensor, it induces an ac signal based on wheel and tire speed. It is also referred to as a tone ring or sensor rotor.

throttle position sensor (TPS)

A variable resistor connected to the throttle plate shaft that produces different current levels for different throttle positions.

traction control systems (TCS)

A system that electronically controls the brakes, differential, engine, and transaxle to help reduce tire spin upon acceleration on slippery pavement.

wheel speed sensor

A magnetic sensor used in an anti-lock brake system to measure wheel speed.

yaw sensor

Part of a stability control system that measures the direction of the thrust generated by vehicle movement.