ABS — Anti-Lock Brake System
ABS — Anti-Lock Brake System
ABS prevents wheel lockup during emergency braking by rapidly modulating brake pressure to individual wheels. A locked wheel — a wheel that has stopped rotating while the vehicle is still moving — generates less stopping force than a wheel at the threshold of lockup. And a locked wheel cannot generate any lateral force for steering. ABS maintains both stopping power and steering control simultaneously. The pedal pulsation a driver feels during ABS activation is the system working exactly as designed.
Wheel speed sensors
The ABS module monitors wheel speed sensors to detect when any wheel is decelerating faster than the others — the early warning sign of impending lockup. Two types exist. Passive sensors generate their own AC voltage signal from a toothed tone ring rotating past a magnetic pickup — no power supply required. Active sensors use a Hall effect element, require power from the ABS module, and generate a clean digital signal. The two types are not interchangeable. The ABS module expects a specific signal type at each wheel position. Before condemning any wheel speed sensor, check air gap, tone ring condition, and sensor mounting integrity.
SAFETY: An ABS warning light means the ABS system is disabled. The vehicle will still have conventional braking but will not have anti-lock protection during emergency stops. Diagnose and repair ABS faults — do not dismiss the light.