whats this wire/plug coming from under the fuse panel
 

86 carrera - wondering what this plug is?http://forums.pelicanparts.com/uploa...1722803883.jpg

I think this is the weco connector for the optional "zusatz reinigungs pump" option M286

On my 85 that powers the trunk light, glove box light, dome lights and the clock. I disconnect it when working either the trunk lid open to avoid battery drain.

thanks! definitely don't have the "zusatz reinigungs pump" so good suggestion.
All my lights seem to work so it's not the trunk/glove box/dome lights suggestion.

What year is your car?
From the photo the wire looks like it is red with white stripe.

If it is a red/white (re/wt) wire the 1981 schematic calls out a one pole connector (T1D) that is located behind fuse panel. The T1D connector mates a single re/wt wire from OXY relay terminal 86 to fuel pump relay single rd/wt wire terminal 30. T1D also connects single re/wt wire to pin 10 on T14 located on regulator panel. This re/wt wire connects to the warm up regulator and supplementary air valve.

Naturally there are many other re/wt wires in the schematics but this is the one near the fuse panel with a single polar terminal connector.

Hope it helps