What is referred to as the "exciter" in ABS systems?

In Anti-lock Braking Systems (ABS), the term "exciter" specifically refers to a ring with notched teeth, which is an essential component of the speed sensing mechanism. As the vehicle's wheels rotate, this exciter ring, often called a tone ring, passes by a speed sensor. The notches in the ring create a varying magnetic field that allows the sensor to detect the wheel's rotation speed. This data is critical for the ABS control algorithm, helping to prevent wheel lockup during braking by modulating brake pressure based on the detected wheel speed.

The other options refer to components and functions within the ABS system but do not accurately describe the "exciter." A sensor that detects wheel rotation is indeed part of the system, but it is not the exciter itself. The control module for braking is responsible for processing signals and controlling braking actions but is distinct from the physical exciter component. Similarly, a type of brake fluid, while necessary for the operation of the braking system, does not relate to the "exciter" aspect at all. Therefore, the identification of the exciter as a ring with notched teeth highlights its role in the detection process critical for the functionality of ABS.