Speed sensors generally are not serviceable. The sensor needs to be replaced. It should be an easy change out, either bolted on or screwed in.
You may want to check the fuse that socket is running to.
You look at the rear of the engine on top of the bell housing for the transmission you will see a wire and a black sensor. Unscrew the sensor and replace it with a new one from places like www.autohausaz.com Cheap easy fix to those hot stall issuesohlordwww.proudtosaymadeintheusa.com
It has to be done by the dealership, who has the instruments to access the cars computer, unless you can fix the problem that made the light come on in the first place (usually an O2 sensor) in which case the light will reset itself after a few starts.
The short circuit location can be found by a diagnostic tester. When the short circuit is located, replace the wiring or switch.
ck for vacuum at map sensor hose, if it is vacuum present replace the map sensor.
buy all new light fixtures and completely rewire the brakes
Probably the speed sensor on the transmission.
did you check the speed sensor on the side of the transmission?
it could be the speed sensor or bad cluster. the speed sensor is around $100 at your local parts store.
speed sensor
You can try cleaning the map sensor and checking turbo speed sensor.
you dont fix it you replace the speed sensor i have a 98 zx2 same thing happened to me the speed sensor went and the check engine light stayed on until it was changed also no spedometer worked only the tach worked