Speedometer giving false reading

[mxvet]

my 07, with 2,500miles is 1mph below the speedometer...at any speed, according to my trusty Garmin.

[qbee42]

<div class='quotetop'>QUOTE(madler @ Sep 14 2007, 01:00 PM) [snapback]512570[/snapback]</div>

In theory a GPS could compute 3D velocity since they compute a 3D fix (actually 4D including time). However they are much less accurate in the vertical direction than in the two horizontal directions, especially when moving. I use a GPS when flying, and the thing does try to estimate climb and descent rates with the 3D fix. However its not very accurate compared to the standard air-pressure driven vertical speed indicator.
[/b]

I find they do pretty well indicating vertical speed. My Garmin provides a good 10560 ft/min reference when dropped out the window, as long as you give it time to reach equilibrium. Other makes and models will provide varying reference speeds depending on their weight and drag characteristics. If used in a vacuum, they are only good for measuring vertical acceleration.

Tom

[bwilson4web]

When I replaced my tires, I took a short trip along a road with mile markers and cross checked the trip meter mileage with the markers. This allows me to figure out the error and deal with it.

My current tires have less than a 2% error with ground truth miles.

Bob Wilson

[alanh]

If I'm reading that regulation right, it doesn't say that the speedo has to register 10% high; it says that the speed must be at least the actual speed and no more than 10%+4km/h over. Because it can't read under, I can see Toyota biasing it a few percent over, but 10% seems excessive.

As far as can tell, my US Prius reads very close the actual speed. I'll have to dig out my GPS and test it.

[ken1784]

<div class='quotetop'>QUOTE(viking31 @ Sep 14 2007, 10:50 PM) [snapback]512463[/snapback]</div>

Hi Ken,

Are you implying that a dealer "could" adjust the speedometer if need be? Previous posters (perhaps uninformed) have indicated it is impossible to adjust the speedometer in any way.
[/b]

I meant replace the speedometer with good one meeting the regulation.

It seems deceitful of Toyota to intentionally have the speedometers so off calibration.
[/b]

Toyota and all car manufacturers are just following the regulation.

Ken@Japan

[Mike Stobbe]

Reply to Paul B re speedometer error. I don't know how to fix a speedometer, but I wouldn't take your dealer's word that it can't be fixed. That's bullshit. Demand to speak to a Toyota technical manager. Remember, this is also effectively shortening your warranty, so keep your record of the dealer's measurement if you have one. You might also try calling a specialist speedometer repair shop. Good luck! Mike Stobbe.

<div class='quotetop'>QUOTE(Paul B @ Aug 17 2007, 01:58 AM) [snapback]497691[/snapback]</div>

Hi, my first posting.

I have a 2007 Prius T spirit and noticed that the speedometer was reading 5-6 MPH above the reading given by both my Sat Nav PDA and GPS speed camera detector.

My dealer has checked this with a speed gun device and has found that the speedometer is reading 10% above the actual speed. He did the same check with another Prius and found exactly the same problem.

Now I understand that most speedometers read slightly higher than actual speed to give a margin of error but 10% is way too high an error.

Not to mention the fact that when the speedo is reading 70 MPH the car is actually doing 63 MPH, it means that for every 10,000 miles driven, the mileage counter reads 1,000 miles higher than it should which will reduce the trade-in value. It also has an effect on the MPG as this relies on the speed reading to calculate its values. The sat-nav will also be effected i.e. time of arrival.

My dealer says that this problem cannot be corrected as there is no adjustment for the speedometer.

Can anyone help ?

Thanks, Paul.

PS, I saw on another thread that the steering wheel buttons should light up when the headlights are on - mine does not. Is this just a European thing ?
[/b]

[patsparks]

<div class='quotetop'>QUOTE(madler @ Sep 15 2007, 02:30 AM) [snapback]512570[/snapback]</div>

(If you drop a GPS down a mine shaft, it will read zero mph -- until it hits the bottom.)
[/b]

What speed will it display then?

If you know your speedo is out adjust for it, so what.

[madler]

<div class='quotetop'>QUOTE(patsparks @ Sep 15 2007, 03:26 AM) [snapback]512943[/snapback]</div>

<div class='quotetop'>QUOTE(madler @ Sep 15 2007, 02:30 AM) [snapback]512570[/snapback]

(If you drop a GPS down a mine shaft, it will read zero mph -- until it hits the bottom.)[/b]

What speed will it display then?[/b][/quote]
%#$*@@***!!

[patsparks]

<div class='quotetop'>QUOTE(madler @ Sep 16 2007, 02:56 AM) [snapback]513050[/snapback]</div>

What speed will it display then?
%#$*@@***!!
[/b]

Oh

I checked my speedo against my GPS and had an error of about +1 to +2 km/h at around 60km/h. Pretty good really.

[silly]

I've edited my post about a problem with my speedometer reading high. It ended up that I had accidentally hit the km/h button instead of having it set to mph.