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:

    Installing the wheel
    1. Clean the contact surfaces on the wheel and hub. 2. Lift the wheel and place it on the hub. 3. Install the wheel bolts and tighten handtight. Using the lug wrench, tighten crosswise until al ...

    Locking or unlocking the vehicle with the key blade
    Keyless drive keyhole cover The driver's door on vehicles equipped with keyless drive can be locked or unlocked with the remote key's detachable key blade if necessary, see page 59 for in ...

    Using an integrated booster cushion
    Stage 1 1 Pull the handle (1) forward and upward (2) to release the booster cushion. 2 Press the booster cushion rearward to lock it in position. Stage 2 1 With the booster cushion in ...