newbolddm

Several hundred more miles driven and still the negative cable solution worked on my Super Duty. I've not had any additional GPS glitches since the fix.

Thanks to this forum and everyone on it!

5111

I just tried disconnecting the battery cable. We'll see if it makes a difference on my truck. I don't see why it would, especially since I just got the newest MFT update that should have a fix for this on it... But it doesn't. I'll post up if the battery disconnect fixes my problem.

I do have 275-60-20 on my truck...it came with 275-55-20

If Ford uses tire size to calculate GPS speed and position, it does make sense that it would be off like mine is. But it also seems ridiculous that Ford would prioritize the tires' input over the satellite signal. I have an strong satellite signal more often than a weak one.

If the battery cable doesn't fix the problem, I'll be off to see the dealer on Tuesday (can't take it on Monday).

5111

I am almost afraid to post this for fear that I will jinx it, but the battery disconnect seems to have fixed the issue. I disconnected the battery and let it sit for a couple of hours while I watched TV. I then drove 25 miles on a twisty route consisted of city and highway and it stayed spot-on. I turned off the truck and went inside. About 30 minutes later I drove a similar 20 mile route back home and it still stayed accurate. So I would tentatively say that It is cured!

I don't know why Ford would have done it this way, but at least it appears that the fix is simple. Thanks for the help.