WARNING:
Never return the key to position 0 or I when the vehicle is in motion.

0 The ignition is off.
I The ignition and all main electrical circuits are disabled.
Note: Do not leave the ignition key in this position for too long to avoid discharging the battery.
II The ignition is switched on. All electrical circuits are operational. Warning lamps and indicators illuminate. This is the key position when driving. You must also select it when being towed.
III The starter motor is activated. Release the key as soon as the engine starts.
General information
Steering wheel lockFord Focus Brake Booster - Description and Operation
The brake booster consists of:
brake booster assembly
brake booster vacuum hose
brake booster vacuum check valve
The brake booster is a single-diaphragm type which utilizes engine vacuum to
reduce brake pedal effort and travel. The brake booster is divided into separate
vacuum and ...