I was playing with the test mode on the way home and would watch the ENG mode that displays the MPH. The problem that I noticed was that the needle for my speed display was about 2-2.5 MPH faster than the digital reading on the test display. This was true regardless of what speed I was doing. I even used cruise control for a while and still the readout would say for example 67.5 while the spedometer looked like it was 70.

Has anyone else noticed this???

 

Get a GPS unit or a friends and find out which reading is correct.

 

Mine is the same way. The analog speedo was 2.5 to 3 off from the digital speedo.

When I put the 285/60R18s on it, my analog speedo is now correct Go figure....

I checked mine against my GPS and a few speed wagons at different speeds. most important to me is that the down low is correct, the next town over loves to issue tickets for speeding in the 20 mph areas. They will give you a verbal warring for 5 over, but it is the time lost that gets me.

 

They are all off by 2 mph for some reason. I remember a thread a year or two ago about this. I fixed mine when I replaced the gauge overlay.

 

I had a GPS unit driving to FL a few weeks back and the the needle was over by 3 mph.

 

mine is off by about 1.3 MPH. I have a GPS which is spec'd at .1 MPH accuracy, but it requires good satelite signal and a flat steady cruise control area to test it. I also calibrated the GPS against a number of those speedometer test signs (you know the ones from 1 to 5 miles) and ran it at 60 miles per hour and timed it. The GPS was "right on" the speedometer needle shows me going faster than I am by 1.3 miles per hour.

If you by a Microtuner you might be able to correct the error. The input is by tire hight in 1/4 inch increments so that ought to take care of it. I have bought the Microtuner and love it so far but haven't tried to correct my speedo yet, but I am going to.

Tom Hall

 

Maybe this is to help prevent us from getting tickets??? So basically mine says 70 when actually I'm driving 68. So that's why I don't have that many tickets!!!! Also makes it seem faster to the driver

 

Yeah. It probably actually is a good thing.

 

I'm not a GPS expert but, they're only as good as the signal that they're recieving.

They constantly crunch data recieved from all the satellites and thus, if they are loosing and gaining strength off and on, you're not going to have a 'precise' MPH reading.

Mind you, most handheld units only can pinpoint on the surface of the earth down to around 10 feet thus, I don't think it's feasible for it to be 'exact' on the MPH...

If you're using something that is 'military issue' or similar, okay...maybe then you're getting some damn good data but, at this point in time, the data is only as good as the unit you have and the reception you're receiving.

RP

 

Or maybe its to keep us from getting full value from the warranty??????

if you average 40 MPH for 36000 miles and you are actually going 37.5 MPH then you are registering an extra 2.5 miles for every 40 registered...

36000 divided by 40 = 900 X 2.5 = 2250

36000-2250= 33700 or 3 years, which ever comes first....

Just a thought.........

 

it would only make sense that the reading that the odometer gets is the reading from the digital speedometer though and not the analog speedometer... Thus the warranty mileage would be the same as the mileage calculated from the digital speedometer multiplied by the truck computer's clock.

I dunno, I like the "Hourmeter" in my wife's Chevy, (the Chevy was not my idea) if you ask me that is what they should calculate the engine life from and not the odometer. Sitting in city traffic for 3 hours in 100+ degrees is a lot harder on your truck than cruising at 65 for three hours but with an odometer reading it comes out that the 3 miles you went in three hours is better for it.