Odometer Telling The Truth?

[Gbenzx01]

484 mile trip here to NC & odo said it was 568! So decided to do some testing when we got back on us 1 hwy where FEC Railway I used to run has accurate mile markers.
On a ten mile run south it clicked off 13.1.
Going back north I puncked the trip meter at every mile marker & got 1.2 every time.
On I 95, not the best for accuracy, the odo showed 24.2 on a 20 mile streach.
How many have checked these things to see if they are telling the truth?
Our 1st clue was on the trip to NC with known distance that we've traveled many times.
Second clue was the 19mp gal in this truck with 4x4 that I did not believe. We're talking 20-25% more miles than is actually traveled & what is this doing to our warrantee?
Don't know abt ya'll but me'll get the thing by the good folks, yes they are thank god, at Garber Chevrolet here & see what they want to do bout this little eager beaver digital wonder.
Had this happen once before with a 98 Mitsubishi Montero that was recording 1.3 for every mile it rolled & had to replace the thing.
If you elect to check it out try to find a good measured distance because road markers are not always the most accurate.
Thanx, Gben

[Captain Mal]

Gbenzx,

Interesting. What is the speedometer doing if the odomoter is so far off?

I've been lucky as my gps shows both my odomoter and speedometer to be quite accurate at most speeds.

[FirstDiesel]

Stock wheels and tires???

[VA_Dmax]

I have noticed that mine is off slightly also. I have the stock tires still, but noticed my speedo reads slightly faster than actual speed, and mileage is a little higher, but not nearly as much as 3 miles off in 10 miles. I think I was off a few 1/10's in a 10 mile stretch. But I pass by those stationary radar moniters that the police leave out and it always shows me 3-4 mph slower than what the speedo reads.

[Raptorrider2001]

First noticed mine not long after I bought it. On a trip to Utah, my GPS showed almost 700 miles less than the speeoometer was showing. Don't remember the exact numbers but the truck said nearly 3400 miles total trip and the GPS was a little over 2700.

[FirstDiesel]

VA_Dmax

I've never owned a vehicle that's not off by around 2-4 MPH at around 60-70. The thinking is that it is a built in fudge factor so you aren't getting tickets if the speedo is off a little the other way. Ever wonder why most cops don't stop you if your 6-8 MPH over the limit? It's because your probably only 2 or 3 and they let that slide.

[Gbenzx01]

Thanx Gents for Response,

Capt Mal the Speedo is only 1 - 2 mph fast & yes GPS is way to go. Hope to have a new Garmin 5 before too long & no the fuzz don't argue with the GPS speed.

Yes 1st Diesel still stock
Can't seem to wear out 245 Fire Fits fast enough - 23k mi. Will go to 285 Cooper or Yokahoma.

I wonder if these odometers can jump mileage if an over &/or under voltage occurs.
My nephew tells me that his Silverado he thinks jumped more than 2000mi when he used the jumper cables to help a lady get her car started.
Said he would not have noticed except he was checking mileage for oil change the following day!
If the dealer offers new odometer I'll accept that although I don't like them monkeying with things electrical. They did do the updates however with no quirks or squawks but something tells me (DP) the Radical Idle will be back!
If they just record this odometer problem in the VIN computer for say 20% fast error would that be ok? Would you just go for the new one?

Thanx, Gben

[VaDmax2003]

On a recent trip from Portsmouth, VA to Chattanooga, TN (approx 680 miles) my GPS and odometer (2003 35HD crew cab with Allison /DMax) were within 3 miles of each other. We averaged 71.5 mph for the whole trip which was all interstate except for 2 miles to nearest interstate access. MY 96 Suburban 2500 with 454 would have a speedometer reading consistently 1.5 miles faster than GPS speed when traveling 60-75 mph.

[VA_Dmax]

First Diesel,

I can see where a few mph off at 60-70 would be normal. But showing just about 40mph and passing by and reading 34-35 on that radar display. Thats about a 12% error if my math is right. (5/40) But I think I know of an easy fix.....just have to wear out my stock set of tires and get something with some more diameter!

[1BADDMAX]

I'm running 235/85/16 Michelin LTX M/S. They are about one inch taller than the stock tires. Last night I checked my speedo with a GPS and noticed up to about 50 MPH it was accurate at 70MPH I was really doing about 71-72.

[AlanL]

Hmm...I've been toying with the idea of going to 265/75 tires, but didn't want to mess with the speedometer/odometer.

Perhaps its calibrated (accidentally) so those tires are a better match anyway.

[DMAX Daddy]

I need to get a GPS to verify, but..

With the 265/75's, when My speedometer shows 50 I think Im actually doing 53 or so.

What is a good, CHEAP, GPS that has this function?

[ryeguy]

According to my Garmin GPS 3+, my speedo was almost bang on with the stock tires. With the 265 Coopers, it's out by like 3.5% to my advantage (going faster than it reads).

The only thing that I have a beef about, is occasionally the trip odometer will bump over 0.1km upon re-startup (after fuelling). I've noticed this 'cause I record every fuel tank through the truck that I can, particularly on long drives. And it's happened enough that I *know* I didn't write down the number incorrectly before I powered down the D/A.

--Rob