Yoni

already changed the speed ensor over transmission it seems that it works a little bit when heat is on

musiclicker

I own a shop, and did you check to see if the new sensor had output? Hook a multi-meter to the terminals on the sensor, set the selector to read AC Mili-Volts, or the lowest scale on the AC setting (not the DC setting as one might think) and as the engine speeds up, the wheels spinning, with the transmission in gear, you should see the meter go up as the speed increases. If not; check the sensor to make sure it is good. Check by hooking to meter (with the sensor out), and pass a metal object such as a wrench by the magnet on the sensor back & forth quickly. If you have a reading on the meter, your problem is inside the housing. If all of this checks good, but you still have no speedometer, then trace the wires back to make sure they are hooked up, and that you are getting a good ground. If you get a little reading with the heat on, then that makes me think you have a loose connection in the dash.Glad to help out, Good Luck!!!