My speedometer ethier says that Iam going slower then I am or sometimes doesn't work at all and other times its fine. Took to a mechanic and they said that they don't know whats wrong with it and to take it to a gm dealership and they would have to take apart the instrument cluster. also is you have any guides or anything about how to take it apart please share. Tried to find a haynes magazine but no one around here has one. Just wondering if someone has had this problem or if someone knows how to fix it or what it might be. Thanks for you time.