What component is essential for the Anti-lock Braking System to function properly?

The essential component for the Anti-lock Braking System (ABS) to function properly is the wheel sensors. These sensors monitor the speed of each wheel, providing critical data to the ABS control unit. If a wheel is found to be slowing down more rapidly than the others during braking, the system can intervene by modulating brake pressure to that wheel, thus preventing it from locking up. This helps to maintain vehicle control and stability during emergency stops or in slippery conditions.

While brake fluid, brake pads, and piston assemblies are important components of the overall braking system, they do not have a direct role in the operation of the ABS. Brake fluid is needed for hydraulic pressure, brake pads provide friction for stopping, and piston assemblies help to apply force to the brake pads. However, without the wheel sensors providing real-time data to the system, the ABS cannot effectively prevent wheel lock-up and improve vehicle safety.