While working on my air intake system I pulled the cable connected to the speed sensor out of the connection near the intake manifold, although I still don't know how, with the cable disconnected which would be equal to a bad sensor I still had power to the speedometer on the dashboard, a big green 0, so I thought that me speedo was working, it was not until I drove up the driveway did I know that the speedo was not working, so the first question is do you have power at the dash indicating a speed of 0, if not than I would suspect a fuse or loose wire leading to the speedo is the problem, if you do have a "0" then I would check the connection to the speed sensor near the motor and if that is good I would suspect the sensor itself is bad.