GPS error due to 37" tires?

[Huck]

This all sounds screwby to me. GPS shouldn't have anything to do with speedo


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[Jordan@Apollo-Optics]

This all sounds screwby to me. GPS shouldn't have anything to do with speedo


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Another member said their dealer told them the Ford Nav only pings the satellite once every 20 mins. It relies on the vehicles sensors during the other 19 minutes it's not communicating. Have the speedo read 50mph when you're really going 53mph over 20 minutes can make a difference.

 

[Huck]

If you pull up "where am I" in the gps it shows real time lat/lon with elevation. And it changes constantly. I find it hard to believe it pings only every 20 minutes. The heading would be all jacked up


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[Huck]

Ok so the photos suck and are close to unreadable but I will describe. Drove down a road today at lunch that has some minor ovation change. While watching the "where am I?" Screen it gave real time readout a of elevation. Changing ~ 30 feet up and down over about a mile.

Now the factory maps have no topo information on them they are flat road atlas'. So there is no sensor to tie to elevation.

So the dealers that said it's tied is full of shit. It reads real time off gps for location. Lat / Lon changed as well as I traveled. Not every 20 minutes.




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[Orionkhan]

I guess we should figure out if effects any increase in tire size diameter. So is everybody running 37's having this issue? Those that aren't, was there some sort of corrective measure taken like having the speedo recalibrated or reinstalling the Nav?

 

[tec548]

I have a hard time understanding why Ford does not just use the GPS system for positioning either. I can tell you that this problem started with the install of my 37's, then I got frustrated and installed my 35's and the problem went away. Put the 37's back on and I'm slowly falling behind on my NAV tracking again. I then went to the dealer and THEY told me that Ford NAV uses the trucks sensors for positioning.
None of this that I have posted is supposition or made up. This is a real problem that I am having and hope to get a fix with the help of you guys.
Yes, recalibrating the speedo would fix the issue... I think... according to Ford (Tomball anyway) the tire size lives (rev/mile) in as many as four different computers and they (Tomball Ford) cannot reprogram after 10' models. I don't know how true any of this is that I was told. This is why I'm asking here. Please, let's stay on point and argue facts. My trucks NAV system falls behind with 37's installed and corrects position about every 20 minutes or when restarted.
Anyone else have their truck on 37's with a factory NAV unit? I know your out there, let's hear from you. Did you fix it, have you not bothered with it?

Thanks again brothers!

 

[The Car Stereo Company]

the vehicles speedo is tied into the gps. all vehicles with nav will have it, and many others without nav too. in my industry it is called the vss wire. vss stands for vehicle speed sensor. every vehicle will have some sort of speed sense. but what i dont get, is if it is off, it should continue to be off, and get farther and farther away the more you drive at an exponential rate. strange why its only off by a little bit at all times

 

[tec548]

It's not. It starts exactly where I am. As I drive it slowly get further and further behind until it corrects itself to where I actually am. Then as I drive on it slowly falls behind again.

 

[BramageDained]

It's also possible that on that screen it polls constantly.

 

[The Car Stereo Company]

It's not. It starts exactly where I am. As I drive it slowly get further and further behind until it corrects itself to where I actually am. Then as I drive on it slowly falls behind again.

so it is doing what i thought it was.