I purchased a 89 Gta with no engine no trans. I recently bought a 87 Iroc. THen took the engine and trans with harness and computer out of the iroc. everything thing is in but the iroc harness has an additional plug with 2 pnk/blk 1 tan/white besides the 15 pin plug .

Any help????

 

did you take the harness out of the gta yet.as i did this with my car an we got many hours in getting it worked out i took mine from a 88 formula an put it in my 87.if i had it to do over i'd of got a painless stand alone harness..im not sure about a iroc harness..