Just swapped in a npi shortblock pi head combo in 2002 mustang gt. Had a high idle, troubleshot that for awhile, Noticed speedo was going haywire and odometer was going up. pulled trans harness, ohmed it out works fine. started car without trans harness idles just fine, speedo is still going haywire without harness, what is going on. where is a good point to start. With the o2 sensors unplugged the pass side is still showing max volts.
