I bought the harness (it also works on my '86) and couldn't stand not knowing
what it was, so I (carefully) took it apart.  What it is, is an op amp and 
some other misc parts, which together make "an active filter". (One could 
probably build it for < $10.)  I started generating a schematic, but quit 
because it didn't seem too many people were interested.

- Frank

 >Thanks for the reply, I bought the harness today and will probably install
 >it the next time I change oil when hopefully the temp here in WI will be
 >above 0.
 >
 >My driveability problems were exactly as described by others who fixed
 >their problem with this wiring harness.  BTW the guy at the parts counter
 >referred to this as a transformer (per the official VW parts fiche) that
 >changes the signal strength--could be I suppose.

\\\\////\\\\////\\\\\////\\\\\////\\\\////\\\\////\\\\////\\\\////\\\\////\\\\
Frank Terhaar-Yonkers
Cisco Systems, Inc.
Engineering Services, W2 F3 5
7025 Kit Creek Road  PO Box 14987
Research Triangle Park,  North Carolina  27709
fty@cisco.com   voice (919)472-2101   FAX (919)472-2940
pager (800)796-7363 pin 1008366 -or- fty@airnote.net