Hooked up the laptop to the IROC the other night when I had to go into work (pretty uneventful datalogging). However, on the way back the "dash" portion of winaldl showed my mph steadily increasing. At a stop light the mph would drop to zero. When I was traveling 45 mph by the speedometer the "dash" on the laptop screen indicated 60 to 65 mph. Once I got on the interstate and was running 65 mph (by the speedometer) the mph incated on the "dash" screen of winaldl gradually climbed to 100 mph. When I enabled the portion of the program that showed trouble codes it checked vehicle speed sensor (VSS) even thought the check engine light was not lit.

Being an 86 IROC it has the cable from the transmission to the back of the speedometer with the VSS behind the speedometer. Anyone else ever have this problem, or have to replace the VSS? How much trouble is it?