I learned something intresting yesterday & thought I'd pass on the information. My 94 z/28 A4 stock DD 182,xxx miles set a code 66, rear motor B+. I had a short on the green wire & after opening the wiring harness traced the short all the way back to the Electronic Brake Control Module (EBCM ~ computer). (Note to self ~ ring both ends of the wire at connectors BEFORE opening wiring harness) Called my local Chevy dealer to order one & he said the part is no longer manufactuered by GM He found one on the parts locater at some Chevy dealer in NY & the list price was $1, 049.88 . I called all the local Part Stores & they ran between 2 ~ 3 hundred for a rebuilt one, but 5 days to wait for shipping Went to the local junk yard & picked one up for $50 & worked great The only thing you have to watch is that some EBCMs are year specific. So, if you are doing the junk yard crawl & see a same year 4th gen headed for the crusher, you may want to grab the EBCM for a spare.