Your locks are vacuum operated. The simple act of locking the driver's door will lock the other doors, as well as the trunk and the fuel door.

As for the wire you ask about. I assume you mean the one pictured below that comes off the alternater harness and crosses the alternater.



That wire makes it's way along the front of the valve cover and up the front of the intake to plug in at the brass temp seansor pictured below. That sensor is the 212*f thermo switch for the aux fan.



Hope this helps.

__________________
Mike Tangas
'73 280SEL 4.5 (9/72)- RIP
Only 8,173 units built from 5/71 thru 11/72

'02 CLK320 Cabriolet - wifey's mid-life crisis

2012 VW Jetta Sportwagon TDI...at least its a diesel

Non illegitemae carborundum.