Subaru Legacy BN/BS (2015-2019) Owners Manual: Brake system

Two separate circuits

Your vehicle has a dual circuit brake system. Each circuit works diagonally across the vehicle. If one circuit of the brake system should fail, the other half of the system still works. If one circuit fails, the brake pedal will go down much closer to the floor than usual and you will need to press it down much harder. And a much longer distance will be needed to stop the vehicle.

Brake booster

The brake booster uses engine manifold vacuum to assist braking force. Do not turn off the engine while driving because that will turn off the brake booster, resulting in poor braking power.

The brakes will continue to work even when the brake booster completely stops functioning. If this happens, however, you will have to depress the pedal much harder than normal and the braking distance will increase.

Brake assist system

Brake assist is a driver assistance system.

It assists the brake power when the driver cannot depress the brake pedal strongly and the brake power is insufficient.

Brake assist generates the brake power according to the speed at which the driver depresses the brake pedal.

NOTE When you depress the brake pedal strongly or suddenly, the following phenomena occur. However, even though these occur, they do not indicate any malfunctions, and the brake assist system is operating properly.

•  You might feel that the brake pedal is applied by lighter force and generates a greater braking force.
•  You might hear the sound of ABS operating from the engine compartment.