2004 Accent Lost our speedo. At the same time the speedo went out we started to hear a grinding metal sound on acceleration coming from under the car. We took it to a mechanic and he changed the speed sensor but we still have the grinding noise. Speedo went out again after about 15k of driving. Grinding sound never went away. I doubt the nmechanic even test drove the car.
I know the sensor goes into the transmission but i am not aware of how it works. Is it a gear of pulse wheel setup and how easy is it to service??
Going to try and fix this myself if i can. I just need a little help on some info.
Thanks.

 

Tone ring on the wheel.