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:

    Trip computer
    A READ (press to acknowledge/confirm/erase a message) B Thumb wheel (used to scroll among the trip computer menus) C RESET The trip computer stores information gathered from several systems in ...

    Gracenote track identification
    If the vehicle is equipped with the optional navigation system, this system uses a hard drive containing a database that recognizes music on audio CDs. The database contains songs that are cur ...

    Operation
    Settings are made by pressing MY CAR on the center console control panel and using the menus displayed. ...