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:

    Speed rati
    The speed ratings in the table translate as follow: Speed ratings M 81 mph (130 km/h) Q 100 mph (160 km/h) T 118 mph (190 km/h) H 130 mph (210 km/h) ...

    Options and accessories
    Optional or accessory equipment described in this manual is indicated by an asterisk. Optional or accessory equipment may not be available in all countries or markets. Please note that some veh ...

    Setting a speed
    Once ACC has been put in standby mode, use the or buttons to store (set) the vehicle's current speed. This puts the system in active mode. The set speed, for example 55 mph, is shown in th ...