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:

    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 ...

    Convertible seats
    Securing a convertible seat with a seat belt Do not place the convertible seat in the front passenger's seat NOTE Refer to pages 49 and 50 for information on securing a child restraint u ...

    CHECK ENGINE Malfunction indicatorlight
    On-Board Diagnostics II (OBDII): As you drive, a computer called "OBDII" monitors your vehicle's engine, transmission, electrical and emission systems. The CHECK ENGINE light will light ...