Vss location

My transmission will not shift into over-drive, the speedometer and tachometer sometimes quit working. I checked all the wiring and plugs going to the speed sensors and used a meter to ohm out the sensors. The sensor with two pins (closest to the engine) reads about 16 ohms, I couldn't figure out how to take it out to look at it, it has blue plastic around it. The other sensor, with three pins (farthest from the engine) reads either open or closed when you take it out and push the plunger in and out. I'm not really sure how to tell if the sensors are bad.