Help please, I have a 1992 Chevy pickup. The speedometer died. I had the speedometer checked professionally, replaced the speed sensor and buffer unit. It turned out to be a
broken wire from the speed sensor to the buffer unit. I had a wire installed and the speedometer began to work except IT JUMPS LIKE CRAZY WHEN YOU ARE JUST ROLLING.
I did notice that the wires coming from the speed sensor to the buffer were twisted together from the speed sensor. I don't know if this twisting changed something. If you can help,
no mechanic in my area can figure it out

Ron

 

Welcome from Florida. If it was a broken wire causing the problem then why did you change the sensor and buffer? It's possible the sensor or buffer are the wrong ones.

 

I had taken it to a local mechanic and he did all those replacements before discovering it was a broken wire. I will stop by there and see if he kept my old speed sensor.
It must be an unusual problem because no one locally seems to have any answer. Anytime someone starts messing like this mechanic did it makes finding the original
problem much more difficult and creates others. Today I will try backing out the speed sensor just a bit and see if it makes any difference.

Thanks for your reply