Power brakes function only when theengine 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:
Faults in the system
If the information symbol illuminates and Park assist syst Service required is
shown on the information display, this indicates that the system is not functioning
properly and has been disengaged. ...
Operation
Press the button in the center instrument panel to switch this function on or
off. The indicator light in the button illuminates when the function is on.
Depending on the optional equipment selec ...
12-volt sockets
12-volt socket in the front tunnel console
The electrical sockets can be used for 12-volt accessories such as cell phone
chargers and coolers. For the socket to supply current, the ignition must ...
