New to the foum here, and just picked up a 2002 GMC. It's the half ton 5.3L. The speedometer in the truck reads around 10mph too fast at highway speeds. (displayed speed 70mph, actual 60mph) The truck does have some modifications.. It has about 10" of lift, and sits on 37" tires on 20" wheels with 4.88 gears. The engine also has a mild cam and some bolt ons.
I received what appears to be a Predator programmer with the truck, and the seller was not exactly sure why the speedometer was incorrect. I am totally new to programmers on gas trucks and the only thing I have is the actual tool itself and the cable that runs to the OBD port in the truck.. I did not receive any software discs, or cables to attach to a computer or anything.
Looking for suggestions on how to figure out which version of the Predator I have, as I see no part numbers on it, and also how I could go about correcting the tune that is on the truck.