I removed the dash, steering column, and instrument cluster in my 2003 Ram 2500 Diesel to replace the HVAC doors. After I reinstalled the dash and instrument cluster then reconnected everything electrical, the tachometer and speedometer both did not work - the needle was on the clockwise side of the peg. The cure is to hold in the odometer **** (trip mileage or total mileage) while turning the key to the first position - you will see the computer perform both a diagnostic AND a reset of the tachometer and speedometer. Wait until it completely finishes the tach/speedometer calibration, then start the engine. All works fine now. I had thought it was loose connections, etc., but is much easier to cure than that!

 

thanks for this helpful tip!