I am assuming that you bought the truck used like that, not the just the gauge cluster only.
I would take the gauge cluster out and double check the connections, sometimes the wires can pop out of the harness. I happened to me when I recently changed to gauge lights to blue LEDs. For me it was the tach that wasn't working. If that doesn't help, check to see if the needle is still connected. Don't pull on the needle, just lightly push it in to the gauge. If it doesn't move that just means its not the problem. Since it is electric it could be a number of things. You trace the connections on the circuit board and see if their is a break in any connections. You may need to replace the gauge cluster, however I don't know if the mileage will change or even if it will work. You might get the answer from the dealer. Hope this helps, maybe someone that has had a similar issue will chime in and offer better advice or the solutions to your problem.
