Speedometer problem

My speedometer has been off since I bought this truck. But I figured it was the tires. Then last week, I noticed that the speedometer was not going back to 0 when stopping. It seems to be getting worse. It is now at 15 mph when stopped. I know that in the GM products, rapidly cycling the key of and on will put the speedometer back to zero. Any fixes or advise appreciated.

I did do a search and found alot of info on other problems, but could not find this one. If there is a thread on this, can someone point me in the right direction.


Thanks,

Bret