Power brakes function only when theengine is running

Power brakes function only when theengine is running  - Brake system - Starting and driving - Volvo XC90 Owners Manual - Volvo XC90

The power brakes utilize vacuum pressure which is only created when the engine is running.

Never let the vehicle roll to a stop with the engine switched off.

If the power brakes are not working, considerably higher pressure will be required on the brake pedal to compensate for the lack of power assistance. This can happen for example when towing your vehicle or if the engine is switched off when the vehicle is rolling. The brake pedal feels harder than usual.

    See also:

    Overview
    Center console control panel 1 VOL: Volume control 2 MEDIA button 3 TUNE: Turn to navigate among menu alternatives and folders shown in the display. 4 OK/MENU: Press to confirm your selection ...

    Other fluids and lubricants
    A Under normal driving conditions the transmission oil does not need changing during its service life. However, it may be necessary under adverse driving conditions. B Models without headlight ...

    Adjusting the set speed
    After a speed has been set, it can be increased or decreased by using the or buttons. 1. Press and hold down or until the vehicle reaches the desired speed. > This will become the set ...