When would the pump motor be activated in an anti-lock brake system with traction assist?

In an anti-lock brake system (ABS) equipped with traction assist, the pump motor is activated to manage brake pressure and maintain control of the wheels during a braking event. Specifically, when the brake pedal pulsates, it indicates that the system is actively modulating brake pressure to prevent wheel lockup. This pulsation arises from the ABS's cycles of applying and releasing brake pressure rapidly, which is necessary for maintaining optimal braking performance, particularly on slippery surfaces.

The activation of the pump motor is crucial during this process as it helps replenish hydraulic pressure in the brake system after the valves have released it. This ensures that the vehicle can continue to decelerate safely without losing traction, especially in conditions where wheel slip can occur. Thus, the moment the brake pedal begins to pulsate is directly correlated with the engagement of the pump motor working to enhance vehicle stability and control.