Power brakes function only when the engine is running

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:
Introduction
Center console control panel
1 Volvo Navigation System (VNS)* – NAV:
see the separate VNS manual for operating
instructions.
2 Infotainment (RADIO, MEDIA, TEL*): see
the infotainment system o ...
Replacing the battery
1. Switch off the ignition.
2. Wait at least 5 minutes after switching
off the ignition before disconnecting the
battery so that all information in the vehicle's
electrical system can be stored ...
Automatic transmission
P (Park)
Use this position when starting the engine or
parking the vehicle.
Never use P while the vehicle is in motion.
The parking brake should also be set whenever
the vehicle is parked.
...
