Double check you have the right sensor, Some Mazda's have a "speed sensor" that is used for internal trans speed as well as another "speed sensor" that is actually a speedo sensor. Also I think your car actually uses the ABS/wheel speed sensors for the speedo.

Find someone with a diagnostic tool that has real time data logging that can display live vehicle speed while driving.

 

There are 4 wheel speed sensors located on the spindal assy. Of each wheel. Generally if one of these goes bad u will get abs lights and traction control lights. U need a scanner or oscilloscope to check the output of the trans speed sensor as well as the wheel speed sensors. Rotunda makes gauge checker that u could buy and that will hook into the wires at the sensor to manually move the speedo to check the wiring and cluster.

 

hello, i had check everything that all you guys had told me to do i even change the cluster and my speedometer still not working, anyone knows what else that i can do

 

Start diagnosing the wiring.