What is the main function of the electronic control unit (ECU) in an ABS?

The main function of the electronic control unit (ECU) in an Anti-lock Braking System (ABS) is to control wheel slip and prevent lockup during braking. This is crucial for maintaining the vehicle's stability and steering control when brakes are applied. The ECU continuously monitors the speed of the wheels through various sensors. If it detects that a wheel is about to lock up (which would occur if the wheel stop turning during braking), the ECU adjusts the brake pressure on that wheel, either by reducing it or releasing it temporarily. This modulation helps ensure that the wheels continue to rotate, thereby allowing the driver to maintain steering control while effectively reducing stopping distance in emergency braking situations.

This function is vital to improve safety and vehicle performance, especially on slippery surfaces where the risk of skidding is higher. The other options involve functions that are not directly related to the primary role of the ECU in the ABS system. For instance, applying brakes manually or monitoring engine speed do not pertain to the specifics of wheel slip control which is the core responsibility of the ECU in an ABS. Similarly, maintaining tire pressure, while important for vehicle safety, is managed by different systems and not the ECU of the ABS.