I found this same part: 911.617.108.00 in my 1983 SC while removing the aftermarket (Hofco III) alarm system. It was attached to the wiring just behind the passenger side frunk hood strut. The wiring connects into the hood open/close sensor that triggers the frunk light. I don't know why it is there, but I removed it.
Looked up the part number and came across this thread. A few posts above indicate it is for 1986 Carreras only, not before. But this is an interesting case (exception?) in an 83 SC.
I hope my front passenger side marker will still work w/out this diode.
