Which component is primarily responsible for activating the ABS during braking?

The primary component responsible for activating the Anti-lock Braking System (ABS) during braking is the ABS pump/motor assembly. When the system detects that a wheel is beginning to lock up during a hard braking situation, the wheel speed sensors send this information to the ABS control module. In response, the control module engages the ABS pump, which modulates brake pressure to prevent the wheels from locking up. This process allows the driver to maintain steering control while braking, enhancing vehicle safety.

The ABS pump/motor assemblies are vital components because they serve to adjust the brake pressure on individual wheels in real-time based on data received from the wheel speed sensors. This immediate response is crucial for the effective operation of ABS, ensuring that the system can react to changes in wheel speeds as they occur during braking conditions.

Other components like the brake pedal are essential for initiating braking but do not directly activate ABS. Similarly, while wheel speed sensors are key in detecting wheel locking and relaying that data to the ABS control module, it is the pump/motor assembly that physically modulates brake pressure. The brake fluid reservoir, while necessary for the hydraulic system to function, does not play a direct role in the activation of the ABS itself.