GPS error due to 37" tires?

[ALDABRAMAN]

Ok. Did some research on some other F150 forums. Turns out this isn't a Raptor specific issue. It's a Ford issue. Pretty common. The fix I found that worked for a lot of people was to disconnect the negative cable to the battery for a couple of hours. I tried that this afternoon. It worked. My Nav tracks flawlessly now. Nobody really knows why this works. My guess is that the nav will recalibrate itself (ping satellites) with the vehicle sensors after being disconnected from power. That's just my guess. We'll see how long it works.

I'm still going to get a 5Star tune and reset the speedo. But not because the Nav is tracking off course. I strongly suggest anyone having this issue with the Nav to try this method. It's cheap and easy.

* That is odd, interesting if it is a permanent fix! Thank you for sharing and an update would be great!

 

[BAJASVT]

I have the SCT tuner does anyone know if any of the shops out there can reprogram for tire size to fix the speedo? To be clear I know that the tuner has rev/mile adjustment in the options menu... this is for transmission tuning and does nothing for the speedo.

Not true. The speedometer in my truck was off after installing 37" tires. I played with the revs/mile setting on my SCT X4 and used a GPS speedometer app on my phone to compare to the truck speedometer until I got it to read correctly again. No problems with the factory nav and 37s for me.

 

[Orionkhan]

* That is odd, interesting if it is a permanent fix! Thank you for sharing and an update would be great!

Yeah, apparently nobody knows why it works. But its seems to be the fix (for most people). I drove around some more tonight using the nav guidance. Never missed a beat. Stopped for dinner. Used it coming home. No problems. Last night within a mile I could see it falling behind. It was that obvious. Make one turn and I was going through a field, building, or whatever. I really don't care why disconnecting the negative battery cable worked. I'm just glad that it did. If you're having the issue, it's worth a try. Takes a couple of minutes to disconnect the cable and then just waiting for a couple of hours before hooking it back up.

Note: I have a 2014 SCREW. It has the latest nav updates. From what I read, this might only work for the 13s and 14s that have the navs up to date.

 

[Jordan@Apollo-Optics]

I honestly don't know how hard they tried to fix it (re-program). I have been out of town for a week and it was dropped off to them. With that being said... the truck was basically untouched. Very dissappointed in this dealership to say the least.

I don't know what years are affected with this problem but I think it would be safe to assume 11' to 14' are affected.

Does anyone know if any of the tuners out there can reprogram the speedo by going through the SCT? I am pretty sure that it can be done, but does anyone know for sure that someone has accually done this?

Yes, SCT can. Anything OBDII related an SCT tuner can fix. My tuner fixed mine and I uploaded the tune last night. I'll let you know how it works since I'm taking a trip to Baton Rouge after work today.

Orion - I will disconnect my battery cable when I get to my destination in Baton Rouge tonight if the recalibrated speedo doesn't fix it. I'll update the thread with what I find tonight.

 

[tec548]

Yeah, apparently nobody knows why it works. But its seems to be the fix (for most people). I drove around some more tonight using the nav guidance. Never missed a beat. Stopped for dinner. Used it coming home. No problems. Last night within a mile I could see it falling behind. It was that obvious. Make one turn and I was going through a field, building, or whatever. I really don't care why disconnecting the negative battery cable worked. I'm just glad that it did. If you're having the issue, it's worth a try. Takes a couple of minutes to disconnect the cable and then just waiting for a couple of hours before hooking it back up.

Note: I have a 2014 SCREW. It has the latest nav updates. From what I read, this might only work for the 13s and 14s that have the navs up to date.

Yes, SCT can. Anything OBDII related an SCT tuner can fix. My tuner fixed mine and I uploaded the tune last night. I'll let you know how it works since I'm taking a trip to Baton Rouge after work today.

Orion - I will disconnect my battery cable when I get to my destination in Baton Rouge tonight if the recalibrated speedo doesn't fix it. I'll update the thread with what I find tonight.

Thanks to all for the valuable input. Please let me know what you find out with your re-calibrated speedo tune. Who did the tune for you? I have a dyno tune on my truck now, do you think they can take my current tune and "ONLY" change the speedo for me?

 

[Jordan@Apollo-Optics]

Thanks to all for the valuable input. Please let me know what you find out with your re-calibrated speedo tune. Who did the tune for you? I have a dyno tune on my truck now, do you think they can take my current tune and "ONLY" change the speedo for me?

My recalibrated speedo (via SCT tune) fixed my navigation problem. It took about 10 miles on the freeway to fix it but, it works!

Also, the tuner who did your dyno tune should be able to just recalibrate the speedo without needing to redyno the truck.

 

[Orionkhan]

My recalibrated speedo (via SCT tune) fixed my navigation problem. It took about 10 miles on the freeway to fix it but, it works!

Also, the tuner who did your dyno tune should be able to just recalibrate the speedo without needing to redyno the truck.

Good to hear that recalibrating the speedo worked. Mine is still spot on just from the disconnecting the negative battery cable trick.

 

[tec548]

Just drove my truck after the dealer had it and said that they could not fix the issue. I don't know what they did, but I suspect it was either a re-flash of the NAV unit or the battery cable trick. Anyway... my NAV is tracking as it should again. I know I should be grateful to them but they didn't think that they fixed it and I still wonder what was done.

 

[Orionkhan]

Just drove my truck after the dealer had it and said that they could not fix the issue. I don't know what they did, but I suspect it was either a re-flash of the NAV unit or the battery cable trick. Anyway... my NAV is tracking as it should again. I know I should be grateful to them but they didn't think that they fixed it and I still wonder what was done.

That's funny that they didn't even realize that they had fixed it. It's a very curious problem. Glad to hear that you're back on track though.

 

[Nick@Apollo-Optics]

So can the dealership really not recalibrate for larger size tires?