How many of you have checked your speedo and more importantly odometer vs GPS?

I did my first check this morning and my speedometer is off by 2mph at 40mph driving speed. That's 5%!!! I can't even imagine how bad it'll be at higher speeds.

Since I'm leasing it's important that my odometer reads correctly and not in favor of the Red Carpet people.

 

With all do respect (not looking to get flamed), who's to say the GPS isn't off?

 

It's the GPS that is off. The older model GPS's were not dead on accurate. I've got one mounted in my boat under the windshield. In that spot it will read x speed, if I move it out in the open, it will read a different speed and no conditons have changed. I don't know if the truck windshield would have the same effect but I've done the GPS on the truck also. Doing 65 MPH in the truck, the GPS says I'm doing 62-63.
Do the manufactures do this so we save ourselves from speeding tickets?

 

This was just covered 3 days ago in another forum (transmissions?). The speedometer reads high, just like 99%+ of the vehicles manufactured in the last 20 years. It ain't nuthin new and it ain't nuthin unique to your truck. It's just a needle pointing at a number printed on the dash. By law speedometers are not allowed to read low, so the manufacturers make sure the needle reads a touch on the high side to cover their *****.

That has absolutely nothing to do with your odometer. The odometers are very accurate and will remain accurate unless you mess around with different gearing or different size tires. Again, the odometer is calculated by tire diameter and how many times it goes around. This is separate from the needle on your dash pointing at a number printed on a piece of plastic intended to give the driver an idea of how fast he's going.

 

^

I hear ya, but what about the digital one's....aren't they right on the money....I know that's not the case with OUR trucks, I'm just saying.

 

I had time to check the odometer and it's spot on.

 

I to have been pondering this delima. I have a Garmin 12+ GPS and a Scan Gauge which I have connected to the ECM via the dash port under the steering colum. Both the GPS and the Scan Gauge show a 2 - 3 mile differance from the speedo readout on the dash. This has been bourn out many times when I have used the police radar setups to warn driver's of their speed in areas like school sones with their portable radar units. Given that this produces a 5% error over speed reading of the speedometer (thus also to the odometer) that would mean I am reeling off 50 more miles per 1000 miles recorded on the tripometer. Now with the 36 month 36,000 mile factory warrenty it would translate to recording 36,000 miles when actually my truck has really only gone 34,200 actual miles. So does this mean that everyone really only gets a 36 month and 34,200 mile warranty from the factory? If so that would be like someone taking $0.01 from every $100.00 that a major company pays out on payday and puts the penny from everyones pay check into their own private account. That is the same as stealing. Just a thought as I don't believe 3 independent speed recording devices would show the same deviations.

 

HELLO!!!!!!!!!!
Is this thing on? Testing 1-2-3

Hey Eagle dude,
Read the thread again. Yes, your speedometer reads high. BUT YOUR ODOMETER IS ACCURATE! Geesh, do people around here read?

 

That is correct, your speedometer has nothing to do with the distance your vehicle actually travels as recorded by the odometer. The speedometer like any other kind of mechanical or electrical gauge has an accuracy or tolerance.

Therefore it is mandated by law that any tolerance in your speedometer must be reflected in the high range. In other words if you speedometer is off by say 5% then when you really traveling at a speed of 60mph your speedometer must indicate a speed of 63mph.

Your odometer on the other hand must reflect its tolerance reading in the low range. In other words if you have actually traveled 36,000 miles but your odometer is off by 5% it must read 34,200.

5% tolerance is a HUGE tolerance and I can assure you it is much lower but 5 is a nice number to work with…

Oh, a little secret, if your really wanting to try and travel a few extra hundred miles beyond your warranty just install some larger diameter tires and your odometer will reflect less miles then actually traveled. It all has to do with gearing…

 

Sometimes it brings me great joy to see you get bent out of shape.

I believe that the odometer and speedometer receive their signal from the OSSS. One of the reasons your speedometer could be off is because of TIRE WEAR. As your tire wears, the diameter, although just slightly, becomes smaller. Just before you replace your tires, your GPS will be the most at odds. Still, from the factory, it should be 1 or 2 MPH slower than actual.

Guess what though. Your odometer is OFF as your tires wear also. Not what I'd call extremely accurate.

Another note. If you lose your OSSS, your truck will go stupid. You'll lose your speedometer, your truck won't know how to shift anymore, and your odometer will not be accurate at all.

 

only law enforement vehicles have accurate speedometers. or unless u got the connections to oder them through ford for your vehicle. but if u want u can take it to ford have them calibrate it for u so its dead on.