Honda Repair: 90 Honda Accord S light and speed sensor, haynes manual, speed sensor

Question
My 1990 Accord (Automatic) The "S" light flashes telling me there is a poblem with the trans. But also the speedometer does not work, The engine light comes on. I checked the ECU codes and it flashes 17 (speed sensor) The Haynes manual says to take it to a dealer to have the sensor chacked. Can these problems be related? And do I have to go to a Honda dealer or can a regular garage check the speed sensor?  I bought the car used It came like this.They said they changed the speedometer and it did not help.

Answer
Mark,
What you are expierencing is a very common problem on your car. You have a bad speed sensor. It sits on top of the trans. If you check my archives, I explain how to replace it in detail. And yes, the S light flashing and the speedo not working are related.
If you can't replace it yourself, any garage should not have a problem doing it for you.
Good luck.