Speedometer woes

Hi--I have an 05' Avalanche. My speedometer just spins out of control. The needle has a mind of its own and in no way is tied to what speed the truck is actually doing. Any idea what/where to start?

thanks

Hi--I have an 05' Avalanche. My speedometer just spins out of control. The needle has a mind of its own and in no way is tied to what speed the truck is actually doing. Any idea what/where to start?

thanks

Most likley a bad speedometer head.
Check your dealer for warranty or recalls.

Does the odemeter mileage still work right?
Any check engine lights?
MT

I have too many miles for warranty.. odometer still works and there are no check engine lights..

You might check all computer systems for codes and watch/check the speed sensor signal.
Also try a battery disconnect unhook neg first and hook it up last.
And when neg cable is off touch it to positive cable for a complete discharge on computer systems.
If any of that does not help it is time for a new or rebuilt or used speedometer cluster assembley.
Good luck
MT