Modern Toyotas are equipped with a sophisticated safety feature known as the Anti-lock Braking System (ABS). To understand why it makes your pedal pulse, you first have to understand what happens during an emergency stop.

Without ABS, a hard brake application on a slippery surface (like a snow-covered Alberta highway) can cause your wheels to "lock up." When wheels stop rotating while the vehicle is still in motion, the tires lose traction and begin to skid. Once a vehicle is skidding, the driver loses the ability to steer. No matter how much you turn the steering wheel, the vehicle will continue to slide in its original direction of travel.

The ABS prevents this dangerous lock-up by using sensors at each wheel to monitor rotation speed. If the system detects that a wheel is about to stop turning while the car is still moving, it intervenes.

As Raegan points out, the system "pumps" the brakes for you, much faster than any human possibly could. It modulates the hydraulic pressure to the brake calipers dozens of times per second. This rapid-fire application and release of pressure allow the wheels to keep rotating just enough to maintain grip on the road.

The pulsing or vibrating sensation you feel in the brake pedal is the physical manifestation of those hydraulic valves opening and closing at high speed. It is haptic feedback letting you know the system is active. In some cases, you might also hear a mechanical "groaning" or "clicking" noise.

The primary goal of ABS isn't necessarily to stop the car faster (though it often does on slippery surfaces); it is to allow you to maintain steering control. Because the wheels are still rotating, you can steer around an obstacle while simultaneously applying maximum braking pressure.