What's good everybody I got one of the autometers programmable speedometer with the three wire sensor wired everything up the light comes on and needle goes up halfway did the calibration process numbers were going real fast as I was driving but the speedometer is still off by 6 miles an hour or so under ...i reset it did it two more times driving further than 2 miles still the same results I don't understand what's wrong has anybody had a problem like this with those Speedos... any help would be great autometer said the try connecting both grounds together but I don't understand what that would change since everything is working like it should

 

Ive had issues with different gauges and found a solution. Like they said ground the sender and the gauge to the same spot. Make sure good ground with no paint or rust underneath. This puts the sendor and gauge at the same ground potential. I put an ohhmeter at different ground sources throughout the car and couldn't believe how many hundreds of ohms difference they were off from each other. Its easy to do so I would try it first.

 

dam thats crazy thanks for the info and the tip really appreciate it I'll try it thanks