This is the last wire I have to hook up for the entire thing, and I have no idea what wire to hook it up to. I have a 1988 formula, and it has the electric spedo. I really do not want to pull the dash apart to find out which wire is the signal wire to hook into.I just want to run the wire through the firewall, and hook it up under the dash somewhere. I have searched through a haynes manual to find out what wire it is, and I also have the factory service manual from gm, and I can't find an answer here. Please help!!!

 

do u still have the old ecm from your original engine? check for a brown w/ white stripped wire that would be your speedometer wire to the ecm if that helps any

 

I do not have the pcm, in fact I got the car without an engine too!