[billjam]

Originally Posted by Tt surgeon

Mine has nothing like that wire. Perhaps it's part of some aftermarket alarm that shuts off the fuel pumps?

The over-boost switch (aka charging pressure control switch, or charge pressure safety switch) is definitely standard on 930s from 86 on, and I'm pretty sure it is also on all earlier models. It has nothing to do with alarms; it shuts down the engine if boost exceeds 1.5 bar by cutting the ground to the fuel pump relays solenoid coils (terminals 85).