I finished the calibration process and the pointer went to full scale instead of zero

This is most commonly caused by the speedometer not receiving a speed sensor signal during calibration. Check to make sure you have a wire going from the “SIG” terminal of the speedometer to the signal output of the vehicle speed sensor. Good soldered connections for this also help.

If all connections are good, then you may check the speed sensor output from your speed sensor. If you get no output from your speed sensor, you will then need to verify that it is being turned before you replace it. On 2-wire factory type speed sensors, if you are not using the sensor for a computer, then make sure that the 2nd wire on the speed sensor is grounded for proper operation. You may use the Ask A Question icon on our website for information on how to test your existing speed sensor.