Correcting speedo error

A GPS is as accurate at calculating your vehicle speed as is a 'certified' speedo in a police car. So when the speedometer in my 2006 Liberty was registering 107 kph when the GPS was showing 120 kph, I mentioned this at my next service interval. The mechanic came up with a relatively easy fix. He re-programmed the computer to make it think I had different sized tires on the car. He got it dead on. However, the odometer still registers less kilometers than the GPS records. I have verified the GPS odometer with the markers along the highway.

Can anyone confirm that electronically altering the speedometer reading would not necessarily change the odometer as well?

Thanks

Strange, it should correct it too unless speedo gage itself is out of cal (amount a signal to it need to show desire deflection) and if this is the case correcting speedo reading via ECM would fix speed and through odometer off. I suggest you take it back to dealer and have them restore programing and pull speedo gage and have it checked for calibration. I had this problem once on a GM truck and speedo itself was bad.

----------------- TheSnoMan.com

Of course it would alter the odometer too, it's part of the speedometer. Maybe it would be a better idea to find the real problem.

And that would be illegal no?

Steve

That would be odd, but there 'could' be two different calibrations in the computer program.

I doubt anyone here has a factory manual for a Liberty to tell you for sure.

Mike

Why? You want the odo to be 'real' miles.

My CJ7 with 33" tires has an odo gear to make them match the speedometer exactly in 'real' miles.

Mike

Looks at subject, pictures Borat in a green thong/speedo. Pokes eyes with pen.

Depends on what got reprogrammed. Sometimes there are different offset values for the spedometer and odometer, both need to be changed. I don't have the manual for your Jeeps computer, so I can't tell you if it has two locations.

No. It's never been illegal to correct your speedometer.

tw

Illegal to alter the odometer reading though. I even pulled the needle off the speedometer on my old Cherokee to re-adjust the speed to match a radar gun that was being operated in the passenger seat by a police officer.

Since I got my Liberty CRD a year ago, I have kept track of every drop of fuel put in the tank. I use K-Jon Vehicle Record System that calculates among many other things, my KPL, or kilometers per litre. I then take that figure & go to

For the record, my KPL on that trip was 9.79, or 11.0 if bumped 12%. That converts to 23 mpg / 25.9 mpg US. - OR- 27.7 / 31 mpg Canadian. I don't think that's too bad for driving 65-70 mph for the most part.

Thanks for that Doug. I'll mention that when it goes in for service next.

Now, it's never been illegal to correct your odometer readings if they are incorrect. Rolling back odometers is another matter, but if you have the experimentation and documentation that would hold up in a court case, I'm sure you'd be fine, but then, there really would be no need to roll it back, anyway.

The manufacturers generally put the error on the side of showing more miles than you've actually driven, claiming it's impossible to get a "dead nuts" as you put it...or "balls on", etc. reading. However, it most certainly IS possible but the auto manufacturers probably save millions in cutting your warranty 5, 8, 10-12% short. Look for inaccurate odometers even in vehicles equipped with GPS systems.

Since your situation is the opposite of the usual problem and since now your speedo is correct, I'm not sure that most people would jump through hoops or even mention it. I'd like to buy your used vehicles, though!

tw

snipped-for-privacy@frozenorth.ca proclaimed:

Misunderstanding. Correcting your speedometer/odometer to either more accurately or even less accurately isn't in any way shape or form illegal. It is only if you alter the odometer reading to indicate a lower mileage than accumulated. Grey areas possible in somve venues if you intentionally alter the speedometer/odometer to accumulate waaay less mileage than is being done. Further grey area if after having observed an odometer that is overly accumulating you alter it backwards to indicate the actual mileage--in some instances lawsuit level grey area if it causes your warranty to expire early and you are using stock tires and running gear. Dunno if anyone has collected on one of those lawsuits, but they have been filed where there appears to be a pattern of readings in the wrong direction.

Actually, that's what I was infering, 'rolling' back the odometer is a no-no. I remember long,long ago....... Almost every used vehicle taken in on trade at a dealership where I worked had "special" instructions on the work order. Every vehicle had a common problem... "Repair rattle in dash". That was before "Nudge nudge, wink wink" was even heard of. :)