Question

Why is my speedometer gauge jumping around?

Yesterday when coming home from the store my speedometer gauge needle as well as the RPM needle started jumping around and going to 80 MPH on the speedometer while I was going at most 20 MPH.

It would jump around and then go back to normal and then Jump around again?

Is the vehicle still safe to drive and what could be causing this?

It's a 92 Chevy Suburban and has been great since I bought it 5 years ago.

Answer 1

I had that problem with the speedometer jumping around on my 90 Chevy Truck and it turned out to be the speed sensor mounted on the transmission had gone bad and was not detecting the speed correctly.

So it was allowing the speedometer to jump around.

If it's not the speed sensor on yours it could be that the plug to it has came loose or got snagged on something or you could have a bad ground to your vehicles battery and engine and electrical system.

Sometimes it could also be the instrument cluster itself but I would first check the grounding as well as the speed sensor connection.

The new speed sensor for my truck was only $22.00 on ebay and it was pretty easy to install.