speed sensor doesn't work Accord 95

I bought an Accord 95 and the speedo doesn't move, the pin is in cero all the time
I went to some carrepair and the guy told me that was the speedsensor, but I didn't trust him, becuase I replace that sensor two times, and the speedo still not working at all.
I check the voltage in the three terminals as the manual say and looks alright

the next thing that I'm going to check is swap the speedsensor from a 93 civic that my cousin has (and work perfectly) and check both sensor his sensor in my car and my sensor in his car and if it works then I will know is not the sensor and check other things.

my questions is what else could I do?
and if I swap the sensors could I affect my cousin sensor?

Question, other than the fact that your speedo doesn't work, why would you keep replacing the speed sensor. Are there any other clues that have led you to believe it is the speed sensor. Are you getting a check engine light or a blinking 's' or 'd4' light? Have you scanned the ECU for codes? Take it to Autozone and have them do it for free if you do have a check engine light on.

If you aren't getting any other symptoms, than the speed sensors could all be fine and working, and your speedo might just need to be replaced. Or a connection may have come loose.

Please give us more info so we can help diagnose the problem.

The engine light doesn't appear at first or if I driving normal about 40 miles/hr, but If I run faster like 60 or 70 then the check engine appear and in sometimes, rarely the engine shut off.
One thing that I do when the check engine appears is, I turn off the motor and then set it in on again then the engine light dispappear.
that always work, I don't know if this thing could affect something.

Get your car scanned for codes. When the check engine light comes on, it is trying to tell you something. Scan for codes and give us the code so we can tell you what is wrong. Otherwise you/we are just guessing.

yesterday I went to Autozone and the guy didn't know how the check the codes and me neither, (and the D4 was linghtning)

so I go back to my house and I was checking the sensor and replaced for other that I already had, after replacing its still did not work then I check the voltage in my cousin's car (a 93 civic), then I swap his sensor to my car and then it works.
A weird thing happened, I put my sensor in his car (that is sopoused was not working) then it works to, I don't know why, but I leave his sensor in my car and my sensor in his car and now are working both, A really weird thing with this.
How could this happend?
maybe when I remove the sensor I need to take of the energy in my car like removing the ECU fuse or unpluged the battery, I don't know

anyway now is working, I hope not to talk about this again LOL..
Thanks for all your help, now I know more about my car.
see you