ABS Controllers, also known as ABS modules, are electronic control units that manage the Anti-lock Braking System. Typically located within the engine compartment, these units receive wheel speed sensor data to detect and prevent wheel lockup during braking events. Utilizing hydraulic control valves, the controller modulates brake pressure to individual wheels, maintaining directional stability and minimizing stopping distance. Modern units often integrate with stability control systems and feature self-diagnostic capabilities, storing fault codes for troubleshooting. Calibration and programming are frequently required upon replacement, and many units contain internal sensors requiring verification during testing.