[Moot]

Yesterday I reset Trip Odometer A, Garmin and ScanGauge all to 0 miles. I drove 100 miles according to the trip odometer. The results:

Trip Odometer A 100 miles.
Garmin 99.1 miles.
ScanGauge 98.4 miles.

What puzzles me is why the ScanGauge shows 1.6 miles less than the trip odometer. The ScanGauge plugs into the OBD-II port which I thought should get its data from the main CPU.

 

[joefromga]

Doesn't the SG have GPS also and a calibration menu to get it to correspond with your odometer?

This seems to be a common issue

 

[jonsobi]

I checked my odometer recently on a piece of highway with the Mile marker posts.

By the last of ten markers, my odo hit mile 10 about 500 feet before the last post.

Not sure if that helps shed any light on your observations.

 

[Moot]

I have the original ScanGauge that is about 12 years old. No GPS but the newer ScanGauge II might have a model with GPS. I still don't understand why the difference in mileage between the ScanGauge and the odometer being that the SG should be getting the same data as the odometer. My 2004 Chevy 3500 had about a 3% difference between the odometer and the SG. When I sold the Chevy a year ago the odometer showed 819,759 miles but in reality it had 844,352 miles. I didn't reveal the discrepancy to the buyer thinking he may have tried to shave some off my asking price.

 

[Budsky]

Along the same lines- has anyone else noticed the speedometer reads a touch low? I've noticed always when I set my cruise to say, 65MPH, I'm really doing about 66 or a hair more. This is verified by GPS- which is very accurate for speed.
Every other vehicle I've ever owned has been the opposite of this- IOW indicated 65 might be more like 63 or 64 in reality.

 

[ShadeTreeMech]

windage & elevation

Moot,

Next time you're out on the open road, set your cruse control when the Garmin says you're going 70mph. Then go into the setup on the ScanGauge and enter a + or - factor to adjust it's mph reading. When the Garmin and ScanGauge mph's are close to the same, the ScanGauge trip odometer ought come close to matching the Garmin and the Transit's odometer reading (from the info displaywith the decimal digit) for a tank of gas. I think the main odometer reading ends up short over time due to truncation.

Budsky,

The speedometer usually shows 64mph at 65mph with the stock tires on mine compared to two different Garmins.

dwb

 

[Budsky]

Budsky,

The speedometer usually shows 64mph at 65mph with the stock tires on mine compared to two different Garmins.

dwb

That is what I'd expect- never had a vehicle with the speedo calibrated to read slower than actual. Good way to edge into ticket territory unwittingly.

On my 96 F350 the speedometer/odometer can be recalibrated by the owner 6 times, then it locks. Wish the Transit had that feature.

 

[Moot]

Moot,
Next time you're out on the open road, set your cruse control when the Garmin says you're going 70mph. Then go into the setup on the ScanGauge and enter a + or - factor to adjust it's mph reading. When the Garmin and ScanGauge mph's are close to the same, the ScanGauge trip odometer ought come close to matching the Garmin and the Transit's odometer reading (from the info displaywith the decimal digit) for a tank of gas. I think the main odometer reading ends up short over time due to truncation.

Thank you Shade Tree. I will give it a try.

 

[Moot]

My speedometer speed is consistent with the Garmin and the ScanGauge. I also checked it against the Speed Box app on my phone. 65 mph is 65 mph. It's the odometer that is in disagreement with the Garmin and the ScanGauge. No biggie. I just thought that the odometer and the ScanGauge would read the same.