Speedometer stopped working correctly

This evening on my 2007 4x4 2.7, I noticed my speedometer was way slow. While going 60, the speedometer shows 40 ( verified with another vehicle and GPS). It was fine yesterday..

I did notice the speedometer needle is now sitting way below zero. It is a certified vehicle still covered by the bumper to bumper. I plan on taking it in but was curious if anyone else has had this problem.

Also no mods, stock 245/75-16 tires and factory gearing.

 

id try disconnecting the battery for a 10 min, reconnect, and test results

 

Thanks, I tried that with no avail.. Must be a faulty part. I'll let the dealer check it out.

 

Any news on what it was??

 

The dealer replaced the speedo cluster under warranty. They tried several things that didn't work(I can't recall what). Then they swapped a speedometer cluster from another truck. That worked. I have no idea what was wrong with the other cluster. They said it was the first one they saw with a problem....

 

Maybe stripped plastic gears in the needle assembly?

Frank