I have a 2005 F-150 4door short bed that's 4×4. I put a 6in lift not so long ago with 35×12.50×18, and the speedometer started acting up saying i was going 80 when i was going about 30. Any help as why that might be? Any help Is welcome

 

I forgot to mention that is stays stuck at about 100ish everytime i shut the truck off, i did the sweep test and is about 50/50 sometimes it passes something it doesn't .

 

That would be your transfer case malfunctioning. Your truck thinks its in 4WD Low when you are in 2WD, and as a result, your speedometer reflects the speed you would be going if you were actually in 4WD Low. Also, the truck is electronically limited to 98.xxMPH. I know this, because I watched a video on this. I'm curious, did you go search on YouTube for a video on what the fix is?

 

I didnt even know the transfercase could do that. And no i haven't, i hope its a quick fix.

 

I believe its the motor that controls the shifting in the transfer case. It gets stuck, and tries to shift, but after a few tries it shuts off, but tells the ECM that it can't shift.

Finally found the video

 

Thank you for the info, ill try to out asap and ill let you know the results