speedometer error

[65Tuxedo]

I put a GPS in my 07 Taco this weekend and found a large gap in speed readings between the GPS and speedometer.

For example, when the GPS reports 67 mph the speedometer is reading 70 to 71.

I haven't tried to time or measure against mileposts yet, but this difference will have an impact on distance as well, making mpg calculations off.

[topdec]

I have seen this on my GPS as well. Off by 2 or mph travelling at around 60mph or faster.

I have the Dueler H/T tires. Do you think that maybe, we should go with a taller tire (265/75/17) to fix this?

[TACOMATruckin98]

perhaps its just simply the distance off of the GPS? does it ever level out after a while? and, is it all stock?

[topdec]

Mine's all stock... The reading is consistently wrong from MN to Chicago, and back.

[Banshee]

Well GPS's aren't the most accurate things, they just get you in a general area and will give you a fairly close speed.

Do you know how GPS works?

[topdec]

http://www.howstuffworks.com/gps.htm says a GPS receiver's job is to locate four or more satellites, figure out the distance to each, and use this information to deduce its own location.This operation is based on a simple mathematical principle called trilateration.

According to the article, the inaccuracy is in the receiver's cheaper components.

Given the above, I just don't know why the same laptop-gps gave me more accurate info on the 06 Odyssey.

[TACOMATruckin98]

my cheap gps was usually within 1 mph with 4 sats

[RompHard]

One thing that I noticed in all the newer Toyota's specially the automatics, the speedometer says you are going faster than you really are I think toyota did this on purpose to make ppl think they are going faster than they are to conserve on gas and not provoke speeding tickets & unsafe driving, plus if you have bigger tires than it came with stock obviously that will happen too. I rented a 2004 camry and had it at like 100mph and felt like I was going 90mph for sure than took it to the max at 120 on the speedometer before the reg. cut the power and felt like I was going maybe 110 I thought 110 was when the regulator cuts the gas to the engine...

[alankidwell]

Has anyone spoken to dealer service about this? i know it is kinda trivial but i have the I4 and the small tires. the warranty can end almost 2000 miles pr-mature. and the gas mileage is worse (not by much). I took my truck in on the first oil change and they made a big deal about it not being a big deal. My speedo is 4 miles an hour off at 70. (speedo says 70 actual is 66) that is the speed that i drive at the most. So we "give" 2000 miles, but if your transition were to go out at 32000 do you think that they would cover it. Hell no. Also for those who have the 100000 mile warrantys. In the end it really does not matter all that much. But it is kinda the principle of it.

[Ridgerunner]

My truck is 7 yrs old with stock tires/rims and my speedo is dead-on accurate with not only my GPS, but with mobile speed readers and milemarkers. I've read in this forum the newer trucks are having this issue and alan's post reveals a suspicion that you guys should check out.

[chris4x4]

On the newer trucks, I have heard alot about the speedos being off, but it seems the odo. is accurate. The speed sensor is reading correctly, but the speddo itself seems to give the incorrect reading. My GPS says the speed function is +/- .2 mph. I used it in my truck and the speedo is off by a couple of m.p.h., but the odo is accurate. The best thing to do is to use the GPS in conjunction with a scangauge to see what the speed sensor is sending to the gauges and go from there.

[JTDTacoma]

I replaced stock tires (265/65/17) with slightly larger 265/70/17 and used a GPS to check my speed. With new tires and the cruise at 70 the GPS said 69.5. Didn't check with stock tires but would guess it was off a few from factory. Now it's nearly perfect.

So to increase your accuracy increase your tire size if you ever replace them.

[lawnrevenge]

Well GPS's aren't the most accurate things, they just get you in a general area and will give you a fairly close speed.

Do you know how GPS works?

Hahaaahaaahaaa!
I use GPS in my job. You can easily pinpoint location to hundredths of a foot with it and nav systems are accurate as said above to arond 0.2 mph.
My truck (a base 08) is around 5 mph slow at highway speed, but the odometer seems fine (there are government regulations regarding odometer accuracy.) I hope going to bigger tires will fix my speedometer.

[wmatt140]

We also own a Camry Hybrid and I read about the same issue on those forums. Some claim the factory settings are intentionally 3 mph below actual but I don't know if thats a fact.

[WilsonTheDog]

Originally Posted by RompHard

One thing that I noticed in all the newer Toyota's specially the automatics, the speedometer says you are going faster than you really are I think toyota did this on purpose to make ppl think they are going faster than they are to conserve on gas and not provoke speeding tickets & unsafe driving, plus if you have bigger tires than it came with stock obviously that will happen too. I rented a 2004 camry and had it at like 100mph and felt like I was going 90mph for sure than took it to the max at 120 on the speedometer before the reg. cut the power and felt like I was going maybe 110 I thought 110 was when the regulator cuts the gas to the engine...

I'm going to give you a big WTF?! Do you wear a tin foil hat, too? You honestly think there's some "conspiracy" or that Toyota wants to make sure you don't "provoke speeding tickets & unsafe driving"? I won't get into how you can "feel" a 10mph difference at 120mph because I'll start laughing even harder and be unable type.

Wow. At least I got a good laugh out of that.

[WilsonTheDog]

Originally Posted by lawnrevenge

I hope going to bigger tires will fix my speedometer.

It should. Mine is now dead on according to GPS and I was consistently 3-4 mph slow at 70mph.

[chris4x4]

Originally Posted by WilsonTheDog

I'm going to give you a big WTF?! Do you wear a tin foil hat, too? You honestly think there's some "conspiracy" or that Toyota wants to make sure you don't "provoke speeding tickets & unsafe driving"? I won't get into how you can "feel" a 10mph difference at 120mph because I'll start laughing even harder and be unable type.

Wow. At least I got a good laugh out of that.

Thanks for posting that. I tried, but I was laughing and couldnt.

[jhodge83]

my speedo was 2 mph fast according to my gps and my odo was perfect...i put on larger tires and now my speedo is perfect, but now my odo is off. i get to extend my toyota warranty now...haha

[zmtnbik]

Originally Posted by WilsonTheDog

I'm going to give you a big WTF?! Do you wear a tin foil hat, too? You honestly think there's some "conspiracy" or that Toyota wants to make sure you don't "provoke speeding tickets & unsafe driving"? I won't get into how you can "feel" a 10mph difference at 120mph because I'll start laughing even harder and be unable type.

Wow. At least I got a good laugh out of that.

Agreed...the clown that posted that obviously hasn't been keeping up on the news. Honda and Chevy had judgements against them for speedometers being inaccurate.

Just a few links related to said subject:

http://hondaodometerclassaction.com/

http://www.lawcash.com/attorney/4913...rs-lawsuit.asp

[Synapse]

Originally Posted by lawnrevenge

Hahaaahaaahaaa!
I use GPS in my job. You can easily pinpoint location to hundredths of a foot with it and nav systems are accurate as said above to arond 0.2 mph.
My truck (a base 08) is around 5 mph slow at highway speed, but the odometer seems fine (there are government regulations regarding odometer accuracy.) I hope going to bigger tires will fix my speedometer.

same thing here with my base!!! 70mph on the truck shows 65-66 on the GPS. Think it would be hard to get this fixed under warranty?