Speedometer not working

We drove it to advanced auto and they used their meter. The only code that came up was the Exhaust Gas Recirculation system (EGR). The meter didnt pick anything up to do with the speedometer.

How do you manually test?

Electrical problem
2000 Ford Ranger 6 cyl Two Wheel Drive Automatic 185000 miles

The truck has brief intermittant episodes where the antilock braking system light comes on, the speedometer doesn't work and the automatic transmission doesn't shift properly. As I recall isn't there an electrical component under the drivers seat that controls all three of these issues? Is that somethiing that can be easily replaced?

I do have one but its from the late 70's, early 80's. If the steps are simple, ill just buy one.

Electrical problem
2000 Ford Ranger 6 cyl Two Wheel Drive Automatic 108 k miles

My speedometer isn't working, can I fix it at home? How? And How much? Thanks for any help that you can give me