So the speedometer has been off tracking higher since I bought the truck, I've replaced the speed sensor but that didn't fix it. Yesterday I found out about doing the speedometer reset/check, and it goes to 20 mph and 55 mph properly, but it won't continue to 120mph on the check, but instead goes to around 75mph. Now the needle will go to 110+ while driving around 75-80mph, so it's not that the needle can't physically get to 120, but why is it not going to 120 during the reset/check?

 

Are your tires shorter than stock?

 

No, they're standard tires, but I bought the truck used several years ago, and the speedometer has been off like this since before I bought it. But my biggest question is why didn't the needle go to 120mph when doing the check?