Speedometer operates during vehicle movement but is inaccurate and has been programmed
With the vehicle running and stationary, rev the engine, does the pointer move at all?
YES: There is tachometer noise on the signal wire. Check connections and ensure the tach wire is not next to the signal wire.
NO: Next step
Start to drive the vehicle, does the speedometer immediately start to move as soon as the vehicle is underway?
YES: Re-program the speedometer using a measured mile, use mile markers or mark off distance with another vehicle.
NO: Speed signal is low at low vehicle speed. CLICK HERE