[bignick2015]

I have a 2015 Impala 2LTZ with a strange odometer inaccuracy - you might want to check to see if yours does this also. I haven't seen this reported here so maybe mine is just defective. Either the main odometer or the trip odometer is not accurate (probably the main odometer, as the same thing happened with either "Trip A" or "Trip B" displayed).

A properly functioning odometer should tick off each mile at exactly the same "tenths" reading of the trip odometer. For example, every time the trip odo hits XXX.7 miles, the main odometer should increase by one mile. What I'm seeing is the main odometer is increasing by one whenever it feels like it. It's not consistent, and it might increase by one at 0.7 on the trip odo, then 1.3, then not until 2.5, then maybe at 3.4, etc.

My car is fully stock - including the original wheels and tires, no ECM or TCM reflashing/tuning of any sort has been done.

So now I have no idea if the 2500 miles on my Impala are really 2500, or somewhere between 2250 through 2750 (assuming up to a 10% +/- variance). Now think how we could be getting shortchanged on our 5 year/100K powertrain warranties - 5 years is still 5 years, but even a 2.5% "fast" odometer will short-change us 2500 miles of our coverage, for those who drive enough miles per year that they hit the 100 before the 5.

Never had this type of problem in the mechanical odometer days. :WTF:

 

[Impala-Blue-2]

Is it possible that the trip odometer and the main odometer are not synchronized with each other. Have you tested each by driving exactly one mile from when the number changes ? not using one or the other as a guide.

 

[donmateo]

^X2, run tests with mile markers, too.

 

[jtrosky]

If I understand what he's saying, it's nothing about being "synchronized". He's leaving the trip odometer alone and if the main odometer changes when the trip odometer ends in xxx.7, for example, the main odometer should ALWAYS change when the trip odometer hit's xxx.7 - it shouldn't change at xxx.7 one mile and at xxx.2 the next mile (for example) - unless, of course, he resets the trip odometer (which it sounds like he's not).

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[shoman90]

If you reset trip A when you get gas...like I do...and the trip meter is between 10ths.....then the main and trip meters will be unmatched...as they should be

 

[impy2ltz2014]

That's not what he is saying.

If you reset the trip, every time you hit 2.00,3.00,4.00,the main should at least be +1 mile.
But the main is happening at trip 1.3,2.7,3.2, or some strange sequence.

 

[jtrosky]

Of course - but the main odometer should still "flip" to the next mile at the same point on the trip odometer every time (assuming it hasn't been reset). What the OP is saying is that sometimes the main odometer will "flip" when the trip odometer is at xxx.5 sometimes, xxx.2 other times and xxx.7 at even other times (without ever resetting the trip odometer). That should never happen.

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[TSS]

Bignick never stated whether he ever hits reset on the trip odometer for gas, etc or not.

Agree with doing a mile marker test of GPS mile test.

 

[impy2ltz2014]

Shouldn't need to hit reset.

 

[TSS]

Shouldn't need to hit reset.

You are missing my point. ^^. IF he IS hitting reset on the trip odometer, HIS method of calculating whether the main odometer was accurate would be off. Likely he is not hitting reset, but we need to confirm.

He needs to run a mile marker test or GPS test and report back to us. One, all, or none of the odemeters may be faulty.

 

[luckydriver]

i was bored so on the way home did a trial. my tenths were changing a certain distance before i hit the tenths markers on the highway. then it got closer to the same time as i passed the signs. then later it was after i passed the signs that the tenths changed. this was mostly straight road. so if the roads are perfectly marked i guess there's an issue

however the full miles on the odometer always changed at the same point that the certain tenth did on my odometer.

 

[impy2ltz2014]

I did a 6 mile test tonight also.

After a trip to the gas station, I saw at Trip A hit 1.7, then my mileage was xxx0 shortly there after.

At 1.7, 4802.
At 2.7, 4803.
At 3.7, 4804.
At 4.7, 4805.
At 5.7, 4806.

Trip B is not enabled. 2014 2ltz with 20" rims.

After some more distance, I'll try to verify it's still the same.

This was also on light rolling terrain, a couple turns. City type driving, varying stop lights and slow cars.. speed tops was 45mph probably.

 

[bignick2015]

More odo info

More details about my initial post - I normally reset Trip A at every fill-up, and did NOT reset during the test.

I haven't been on any roads with mile markers (no major highways nearby) but just for shiggles I set the DIC to use Metric mode.

EVERY TIME the main odo clicked off a new KM, the Trip A was at XXX.7 km. So it appears that "internally" the main odo counts in km and only changes numbers when a full km is reached. And sometimes one km won't be enough to add a mile when in US mode.

With the main odo only incrementing at full-km intervals (internally), it won't exactly match the trip odo because a km is only (roughly) 5/8 of a mile... so something like this happens:

Trip odo (mi) - Trip odo (internal/km) - Main odo (mi) - Main odo (internal/km)
0.0 - 0.0 - 0 - 0
0.6 - 1.0 - 0 - 1
1.0 - 1.6 - 0 - 1 (main odo hasn't hit 1 mile because it hadn't gone a full mile when the internal count hit 1)
1.2 - 2.0 - 1 - 2 (main odo updated when internal count hit 2 km = 1.2 mi)
1.8 - 3.0 - 1 - 3
2.0 - 3.2 - 1 - 3 (main odo will not update until internal km count hits 4)
2.5 - 4.0 - 2 - 4 (main odo updated when internal count hit 4 km = 2.5 mi)
3.0 - 4.8 - 2 - 4 (main odo will not update until internal km count hits 5)
3.1 - 5.0 - 3 - 5 (main odo updated when internal count hit 4 km = 3.12 mi)

So this just seems like a software/display bug to me, rather than an actual "inaccurate" odometer, but I will still have to verify on a marked highway.

My first VIN digit is a "2" indicating it was built in Canada, maybe the DIC programming is different in Canadian-built cars? Or maybe I need an update?

 

[impy2ltz2014]

Ok- I'm a 1,in usa. ..don't deal with km.

Might switch to km to see what happens. But your theory makes sense.

 

[LS5]

Not Hijacking your Thread here Bignick, but talking about messed up odometers.. I have the same car as yours the LTZ 2LT model and the Digital odometer in the center will read 113kmh and the actual gauge odometer reads I am doing 120kmh ????I cant figure that one out at all.... Yes I am in Kilometers an Hour as well but even when I switch over to Metric and use Miles per hour it does the same thing, the odometers don't match up. anyone else have the same problem..
Darren.

 

[impy2ltz2014]

No. About the only thing I've seen is that it can appear to be off 1 mph on the analog if you are looking at it in the wrong way (not straight on).

Like 40 mph might look like 39 mph if you are looking down on it.

 

[Impala-Blue-2]

Not Hijacking your Thread here Bignick, but talking about messed up odometers.. I have the same car as yours the LTZ 2LT model and the Digital odometer in the center will read 113kmh and the actual gauge odometer reads I am doing 120kmh ????I cant figure that one out at all.... Yes I am in Kilometers an Hour as well but even when I switch over to Metric and use Miles per hour it does the same thing, the odometers don't match up. anyone else have the same problem..
Darren.

I think you are referring to the speedometer not the odometer.

 

[LS5]

I think you are referring to the speedometer not the odometer.

Doh.......!! Yes my bad... Speedometer not odometer... sorry..
Darren.

 

[philf]

I'm in Canada as well, and I gotta say that it would be nice to be able to choose units by display. I'm fine with the speeds and distances being in kms, but that's it. Tire pressure numbers in kPa and fuel economy in l/100km don't do much for me. Maybe I'm just old . The kPa thing is particularly annoying, as 1 kPa is about .14 PSI. I don't think the pressure transducers are that accurate, so seeing the tire pressure numbers swinging around by 5 at a time is disconcerting - until you realizes it's only half a pound on the English scale.

You've got me looking, now, though. Gonna have to check my odo for consistency. We've got a few roads around that are marked every .5 km. Will also compare to my GPS (Garmin handheld - not the one that's part of the car's nav).

 

[impy2ltz2014]

For about every 10 degrees F, psi adjusts by about 1.