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:

    Types of lists used in the manual
    Procedures Procedures (step-by-step instructions), or actions that must be carried out in a certain order, are arranged in numbered lists in this manual. If there is a series of illustrations asso ...

    Cleaning the sensors
    Park assist sensors The sensors must be cleaned regularly to ensure that they work properly. Clean them with water and a suitable car washing detergent. Ice and snow covering the sensors may c ...

    Active Yaw Control (AYC)
    This function helps maintain directional stability, for example when cornering, by braking one or more of the wheels if the vehicle shows a tendency to skid or slide laterally. This is one of D ...