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:

    Infant seats
    Securing an infant seat with a seat belt Do not place the infant seat in the front passenger's sea NOTE Refer to page 48 and page 50 for information on securing a child restraint using ISOFIX/ ...

    The radar sensor and its limitations
    In addition to being used by ACC, the radar sensor is also used by Distance Alert (see page 165) and Collision Warning with Full Auto-brake and Pedestrian Detection (see page 173). This sensor is ...

    Unlocking a channel
    A channel's access code is required to unlock a channel. Unlock all channels This permanently removes all channels from the locked list and makes them available for selection. Temporarily unl ...