Speedometer started going crazy it dropped down 20mph then jumped to 110mph?

Hello,

It sounds like you might have a faulty vehicle speed sensor (VSS).
The VSS is located on the right rear of transmission (see diagram).
The VSS operates by signaling transmission shaft rotation to the ECU and then the data gets sent to the gauge cluster and you get the speedometer to display the value.

The sensor can become faulty over time as it can loose its calibration. Also the wire harness can become loose or corroded. When that happens it can give incorrect info to the gauge and can also just stop working.

You might find this video helpful:

https://youtu.be/f3bETtCIdxM

I have attached diagrams for your reference.

Please let me know of any questions.

Thank you.