Originally Posted by ImBroke

There is a vac pump on the front of the motor. The vac generated goes to a bunch of places to do different things. The big line goes to the brake booster for "power" brakes. Smaller lines branch off of that for climate control, door locks, trans modulator, and shut off being the major ones. For shut off, when the key is on, the vac supply is blocked for the Injection Pump shut off. Turn the key off, and the blockage is removed, supplying vac to the shut off, and the car shuts off. Usually. For the door locks, a vac is supplied to the master lock switch. Lock the door, and a vac is supplied to the yellow with red stripe lines, pulling the lock actuators to the lock position. Unlock, and the vac is removed from the red, and applied to the yellow with green stripe, moving the acutators in the opposite direction. This vac is supplied from the reservoir in the trunk, since the car is off and won't generate a vac like this. Hope this gets you started.