Mike "Wuzzy121". Rest in peace, brother

Go Back   Tacoma World Forums > Tacoma Discussion > 2nd Gen. Tacomas

Notices

Does Speedo off equal Odometer off?

Reply
 
Thread Tools Search this Thread
Old 06-12-2009, 03:15 PM   #1
James08 [OP] James08 is offline
Senior Member
James08 is one of the sharper tools in the shedJames08 is one of the sharper tools in the shedJames08 is one of the sharper tools in the shedJames08 is one of the sharper tools in the shedJames08 is one of the sharper tools in the shedJames08 is one of the sharper tools in the shedJames08 is one of the sharper tools in the shedJames08 is one of the sharper tools in the shedJames08 is one of the sharper tools in the shedJames08 is one of the sharper tools in the shedJames08 is one of the sharper tools in the shed
 
James08's Avatar
Joined: May 2009, #17240
Location: Austin, TX
Gender: Male
Posts: 183
James08's Tacoma Gallery
Does Speedo off equal Odometer off?

I noticed when I had my GPS in the Tacoma the other day that my speedo is off by about 4-5 mph at 75, so I was actually only doing about 70. Since I know this now I don't really care enough to spend money to fix it unles my odometer is also spinning faster than I'm actually going.

What do you think? I called a dealership, but of course they haven't called me back with an answer. Thanks in advance.
  Reply With Quote
Old 06-12-2009, 03:18 PM   #3
James08 [OP] James08 is offline
Senior Member
James08 is one of the sharper tools in the shedJames08 is one of the sharper tools in the shedJames08 is one of the sharper tools in the shedJames08 is one of the sharper tools in the shedJames08 is one of the sharper tools in the shedJames08 is one of the sharper tools in the shedJames08 is one of the sharper tools in the shedJames08 is one of the sharper tools in the shedJames08 is one of the sharper tools in the shedJames08 is one of the sharper tools in the shedJames08 is one of the sharper tools in the shed
 
James08's Avatar
Joined: May 2009, #17240
Location: Austin, TX
Gender: Male
Posts: 183
James08's Tacoma Gallery
That is the response I was hoping for!

So the odometer uses a different system than the speedo? So what happens if I decide to do bigger wheels and tires? Is the odometer system something that can be adjusted to account for changes in wheel and tire size? Thanks again.
  Reply With Quote
Old 06-12-2009, 03:20 PM   #5
Bah Humshit!
brian is one of the sharper tools in the shedbrian is one of the sharper tools in the shedbrian is one of the sharper tools in the shedbrian is one of the sharper tools in the shedbrian is one of the sharper tools in the shedbrian is one of the sharper tools in the shedbrian is one of the sharper tools in the shedbrian is one of the sharper tools in the shedbrian is one of the sharper tools in the shedbrian is one of the sharper tools in the shedbrian is one of the sharper tools in the shed
 
brian's Avatar
Coast Guard: Work and Fly on the Four Fans of Freedom
Joined: Apr 2009, #16011
Location: Roseville, CA
Gender: Dude
Posts: 7,556
brian's Tacoma Gallery
Send a message via AIM to brian
I don't understand how the odometer can be a different system than the speedo? Please explain.

My gps mileage is proportionately off in relation to my odometer in the truck.... same with speed. I get 1.1 miles on the GPS for every 1 mile on the odometer. This same amount can be translated on my speedometer. When I'm doing 60 on the speedo, my gps reads closer to 64.

I've done the math calculations, both are off proportionately by 1.07 or so.

I think you read that wrong.
  Reply With Quote
Old 06-12-2009, 03:37 PM   #6
Senior Member
lasllc has a brilliant futurelasllc has a brilliant futurelasllc has a brilliant futurelasllc has a brilliant futurelasllc has a brilliant futurelasllc has a brilliant futurelasllc has a brilliant futurelasllc has a brilliant futurelasllc has a brilliant futurelasllc has a brilliant futurelasllc has a brilliant future
Navy: Lead PO Submarine Reactor Control Dvision
Joined: Feb 2009, #13507
Location: SW Denver Burb
Gender: Male
Posts: 236
lasllc's Tacoma Gallery
I am pretty sure that there is no fix here. The reported problems ( do a search here ) are too random.

For example, my '09 TRD/OR AC ; the speedo needle is dead on with my GPS, but the odometer is slow by about 4.XX % ie: 104 on the GPS is 100 on the odometer.

The analog needle is error prone just becasuse it is a digital to anlog conversion; also, if you pay close attention at verious speeds you will see it is not a linear error; even more difficult to mitigate.
The odometer is a seperate circuit which probably has a differant set of operationsl specs then the speedo.

The speedo and the odometer are not taken from the same data set as it used to be when there was only a cable from the trans. ( or right front wheel, early VW ) to the speedo head and a set of gears drove everything.
  Reply With Quote
Old 06-12-2009, 03:40 PM   #7
Do Work Son!
rossk35 is one of the sharper tools in the shedrossk35 is one of the sharper tools in the shedrossk35 is one of the sharper tools in the shedrossk35 is one of the sharper tools in the shedrossk35 is one of the sharper tools in the shedrossk35 is one of the sharper tools in the shedrossk35 is one of the sharper tools in the shedrossk35 is one of the sharper tools in the shedrossk35 is one of the sharper tools in the shedrossk35 is one of the sharper tools in the shedrossk35 is one of the sharper tools in the shed
Joined: Mar 2009, #15197
Location: hawaii
Gender: Male
Posts: 869
rossk35's Tacoma Gallery
If your speedo is off the odometer is also off. It shows you going faster then you actually are, so it thinks you're covering more road then you really are.
  Reply With Quote
Old 06-12-2009, 04:15 PM   #8
( ͡° ͜ʖ ͡°)
Jester243 is one of the sharper tools in the shedJester243 is one of the sharper tools in the shedJester243 is one of the sharper tools in the shedJester243 is one of the sharper tools in the shedJester243 is one of the sharper tools in the shedJester243 is one of the sharper tools in the shedJester243 is one of the sharper tools in the shedJester243 is one of the sharper tools in the shedJester243 is one of the sharper tools in the shedJester243 is one of the sharper tools in the shedJester243 is one of the sharper tools in the shed
 
Jester243's Avatar
Name: Dan
Joined: Jun 2008, #7552
Location: Spokane, WA
Age: 36
Gender: Male
Posts: 8,870
Jester243's Tacoma Gallery
Quote:
Originally Posted by briangp View Post
I don't understand how the odometer can be a different system than the speedo? Please explain.

I think you read that wrong.
Here is an answer from Chris from another thread;
Quote:
Originally Posted by chris4x4 View Post
The speedos on Tacomas have always been about 5 mph faster than actual. The ODO is correct, however. Check your ODO against the GPS. If it is indeed in error, call the 800 # in your manual. FWIW, Both my Tacomas gpsed the correct amount of miles untill I changed tire sizes. Then they were a little behind, as I went with bigger tires.
  Reply With Quote
Old 06-12-2009, 04:17 PM   #9
Sooooooper Moderator
jhodge83 is one of the sharper tools in the shedjhodge83 is one of the sharper tools in the shedjhodge83 is one of the sharper tools in the shedjhodge83 is one of the sharper tools in the shedjhodge83 is one of the sharper tools in the shedjhodge83 is one of the sharper tools in the shedjhodge83 is one of the sharper tools in the shedjhodge83 is one of the sharper tools in the shedjhodge83 is one of the sharper tools in the shedjhodge83 is one of the sharper tools in the shedjhodge83 is one of the sharper tools in the shed
 
jhodge83's Avatar
Air Force: former TSgt/E6, 3D172, Cyber Transport, NC Air Guard and prior AD
Name: Jamie
Joined: Apr 2007, #1432
Location: Moncks Corner, SC
Age: 31
Gender: Guy
Posts: 24,601
jhodge83's Tacoma Gallery
no....i was getting a slow reading on my speedo but odo was perfect to road markers and my gps. changed wheel sizes and the speedo was dead on and the odo was off
  Reply With Quote
Old 06-12-2009, 04:19 PM   #10
( ͡° ͜ʖ ͡°)
Jester243 is one of the sharper tools in the shedJester243 is one of the sharper tools in the shedJester243 is one of the sharper tools in the shedJester243 is one of the sharper tools in the shedJester243 is one of the sharper tools in the shedJester243 is one of the sharper tools in the shedJester243 is one of the sharper tools in the shedJester243 is one of the sharper tools in the shedJester243 is one of the sharper tools in the shedJester243 is one of the sharper tools in the shedJester243 is one of the sharper tools in the shed
 
Jester243's Avatar
Name: Dan
Joined: Jun 2008, #7552
Location: Spokane, WA
Age: 36
Gender: Male
Posts: 8,870
Jester243's Tacoma Gallery
If you search "speedometer" along with "odometer" you will get two pages of threads on this. Should be some good reading but some threads have more info than others.

There is a tire calculator to figure out the speedo differences as well; tire size calculator

have fun
  Reply With Quote
Old 06-12-2009, 07:39 PM   #11
Bah Humshit!
brian is one of the sharper tools in the shedbrian is one of the sharper tools in the shedbrian is one of the sharper tools in the shedbrian is one of the sharper tools in the shedbrian is one of the sharper tools in the shedbrian is one of the sharper tools in the shedbrian is one of the sharper tools in the shedbrian is one of the sharper tools in the shedbrian is one of the sharper tools in the shedbrian is one of the sharper tools in the shedbrian is one of the sharper tools in the shed
 
brian's Avatar
Coast Guard: Work and Fly on the Four Fans of Freedom
Joined: Apr 2009, #16011
Location: Roseville, CA
Gender: Dude
Posts: 7,556
brian's Tacoma Gallery
Send a message via AIM to brian
Hmmmmpph... I give up.... I'm content in knowing that my odometer spins slower because of my larger tires, so I sleep better at night.
  Reply With Quote
Old 06-12-2009, 07:53 PM   #12
Senior Member
gjbonner is one of the sharper tools in the shedgjbonner is one of the sharper tools in the shedgjbonner is one of the sharper tools in the shedgjbonner is one of the sharper tools in the shedgjbonner is one of the sharper tools in the shedgjbonner is one of the sharper tools in the shedgjbonner is one of the sharper tools in the shedgjbonner is one of the sharper tools in the shedgjbonner is one of the sharper tools in the shedgjbonner is one of the sharper tools in the shedgjbonner is one of the sharper tools in the shed
 
gjbonner's Avatar
Marines: LAR (Master Gunner/Instructor)
Name: Guy
Joined: Nov 2008, #10420
Location: Northern Idaho
Age: 36
Gender: Male
Posts: 1,289
gjbonner's Tacoma Gallery
Also keep in mind that no matter what GPS you are using there is a +/- of error when it comes to speed, distance traveled, elevation, as well as where you are in reference to 6 8 and 10 digit grids...also didnt i hear somewhere on these threads that if you get bigger tires your odometer will be affected and you will be traveling more miles than what it reads? correct me if im wrong but i know i read that here somewhere.
  Reply With Quote
Old 06-12-2009, 09:20 PM   #13
Senior Member
Raven65 has a spectacular aura aboutRaven65 has a spectacular aura about
 
Raven65's Avatar
Joined: Feb 2009, #14150
Location: Camden, SC
Age: 49
Gender: Male
Posts: 357
Raven65's Tacoma Gallery
Quote:
Originally Posted by rossk35 View Post
If your speedo is off the odometer is also off. It shows you going faster then you actually are, so it thinks you're covering more road then you really are.
Not necessarily. The magnetic sensor in the transmission detects output shaft revolutions and sends pulses to the computer which it uses to calculate speed & distance. It then sends this data in the form of a digital signal to both the speedometer where it is converted into the analog movement of the speedometer needle, and to the odometer where it is directly displayed. It's possible for the digital-analog conversion at the speedometer to be inaccurate while the odometer is accurate.

It's easy enough to test with a GPS - and/or by using interstate mile markers & a stopwatch (or a watch that displays seconds). Drive an indicated 60 MPH (one mile per minute) and when you pass a mile marker, reset your trip meter (or make a mental note of what it's reading) and start your watch at the same time. Hold your speed at exactly 60 MPH indicated and you should hit the next mile marker in exactly one minute - and your odometer should click off a mile at exactly that same point. If your watch hits one minute before you get to the next mile marker, your speedo is off... you're going slower than 60 MPH. If you REALLY want to test it, do that for 10 miles. You should hit exactly 10 minutes and 10 miles at the 10th mile marker.

It's very possible for the speedo to be off while the odo is correct though.
  Reply With Quote
Old 06-13-2009, 04:26 AM   #14
Old & Forgetful
Janster is one of the sharper tools in the shedJanster is one of the sharper tools in the shedJanster is one of the sharper tools in the shedJanster is one of the sharper tools in the shedJanster is one of the sharper tools in the shedJanster is one of the sharper tools in the shedJanster is one of the sharper tools in the shedJanster is one of the sharper tools in the shedJanster is one of the sharper tools in the shedJanster is one of the sharper tools in the shedJanster is one of the sharper tools in the shed
 
Janster's Avatar
Name: Jandy
Joined: Mar 2007, #1138
Location: Lancaster, PA
Age: 46
Gender: Female
Posts: 12,838
Janster's Tacoma Gallery
Quote:
Originally Posted by Raven65 View Post
The magnetic sensor in the transmission detects output shaft revolutions and sends pulses to the computer which it uses to calculate speed & distance.
That's the key point. The speedo & the ODO are coming off the same sensor.

If one of them is off, they're both gonna be off.

People need to realize - the speedometer on the dash (needle) is NOT the actual data. The needle is just a visual for the driver. If the needle isn't calibrated accurately to the numbers on the dash (for a lack of a better way to explain it), then the needle will always be 'off'.

That's another benefit to owning a Scangauge - you see the actual data from the computer. On my truck, the needle is 2mph slower. My GPS & the Scangauge MPH data matches.
  Reply With Quote
Old 06-13-2009, 08:36 AM   #15
Senior Member
JoeSchmuck will become famous soon enoughJoeSchmuck will become famous soon enough
 
JoeSchmuck's Avatar
Navy: Submarine Launched Ballistic Missiles
Name: Joe
Joined: May 2009, #17443
Location: Virginia
Gender: Male
Posts: 255
JoeSchmuck's Tacoma Gallery
Well my truck does what I see the majority of other Tacoma trucks do, the speed reads a little high (by the way almost all cars do) by 1-2 MPH over the 25-70 MPH range. The Odometer is always the same, reads .1 miles less than actual mileage for just under a 10 mile strech.

What does this mean:
1) Your ODO will reflect less mileage than you actually drive on new tires but as your tread wears I suspect it will be close to actuale miles driven.

2) Like so many other cars on the road, the speedometer does not read true speed, most actually say you are going faster than you are. I don't know of a mechanical reason this occurs unless they factor in you could use a larger tire, but I doubt that. I like to think it's a way to keep you under the speed limit, even when you think you are speeding.

I think we answered the thread starters question.

For the few of you saying you have the opposite problems, I strongly suggest you use a different GPS and double check your facts. If you have a problem you should clearly contact the dealership about it.

A little history... Honda had a problem in thier 2002 Accord (could be more but that was all that affected me) line where the ODO recorded more than actual mileage and a law suit occured. The result was the warrentee was extended by 5000 miles.

-Joe
  Reply With Quote
Old 06-13-2009, 08:46 AM   #16
Senior Member
Raven65 has a spectacular aura aboutRaven65 has a spectacular aura about
 
Raven65's Avatar
Joined: Feb 2009, #14150
Location: Camden, SC
Age: 49
Gender: Male
Posts: 357
Raven65's Tacoma Gallery
Quote:
Originally Posted by Janster View Post
That's the key point. The speedo & the ODO are coming off the same sensor.

If one of them is off, they're both gonna be off.

People need to realize - the speedometer on the dash (needle) is NOT the actual data. The needle is just a visual for the driver. If the needle isn't calibrated accurately to the numbers on the dash (for a lack of a better way to explain it), then the needle will always be 'off'.

That's another benefit to owning a Scangauge - you see the actual data from the computer. On my truck, the needle is 2mph slower. My GPS & the Scangauge MPH data matches.
I think we agree... but I'm confused by your statement that "If one of them is off, they're both gonna be off." That's not true. The computer can be calculating the speed & distance correctly based on input from the transmission (as long as you're running stock-size tires) and sending that correct data to both the speedo and the odo, but, like you explained, if the analog speedometer is not displaying that speed accurately due to a calibration problem or whatever, it's possible for it to be off, while the odometer displays the data correctly and counts off the miles accurately.

At any rate... it's easy enough to check.
  Reply With Quote
Old 06-13-2009, 09:09 AM   #17
Old & Forgetful
Janster is one of the sharper tools in the shedJanster is one of the sharper tools in the shedJanster is one of the sharper tools in the shedJanster is one of the sharper tools in the shedJanster is one of the sharper tools in the shedJanster is one of the sharper tools in the shedJanster is one of the sharper tools in the shedJanster is one of the sharper tools in the shedJanster is one of the sharper tools in the shedJanster is one of the sharper tools in the shedJanster is one of the sharper tools in the shed
 
Janster's Avatar
Name: Jandy
Joined: Mar 2007, #1138
Location: Lancaster, PA
Age: 46
Gender: Female
Posts: 12,838
Janster's Tacoma Gallery
Quote:
Originally Posted by Raven65 View Post
I think we agree... but I'm confused by your statement that "If one of them is off, they're both gonna be off." That's not true. The computer can be calculating the speed & distance correctly based on input from the transmission (as long as you're running stock-size tires) and sending that correct data to both the speedo and the odo, but, like you explained, if the analog speedometer is not displaying that speed accurately due to a calibration problem or whatever, it's possible for it to be off, while the odometer displays the data correctly and counts off the miles accurately.

At any rate... it's easy enough to check.
People were thinking the two (speedo & odo) were two different systems.

They're the same and the info comes off the same sensor.

I was simply trying to say, if one of them is inaccurate...the other one will be inaccurate also (and I'm only talking about actual data in the ECU). I keep forgetting that people only have the needle to use as a reference to compare to. In most cases, that needles isn't accurate to the data in the ECU.
  Reply With Quote
Old 06-13-2009, 09:42 AM   #18
There's an evil monkey in my truck
Evil Monkey is one of the sharper tools in the shedEvil Monkey is one of the sharper tools in the shedEvil Monkey is one of the sharper tools in the shedEvil Monkey is one of the sharper tools in the shedEvil Monkey is one of the sharper tools in the shedEvil Monkey is one of the sharper tools in the shedEvil Monkey is one of the sharper tools in the shedEvil Monkey is one of the sharper tools in the shedEvil Monkey is one of the sharper tools in the shedEvil Monkey is one of the sharper tools in the shedEvil Monkey is one of the sharper tools in the shed
 
Evil Monkey's Avatar
Navy: Tradevman (flight simulator tech), Aviation Electrician (F-14a), Computer Scientist(civ)
Name: Robert
Joined: Aug 2007, #2352
Location: Escondido, CA
Age: 52
Gender: Male
Posts: 8,231
Evil Monkey's Tacoma Gallery
Quote:
Originally Posted by JoeSchmuck View Post
2) Like so many other cars on the road, the speedometer does not read true speed, most actually say you are going faster than you are. I don't know of a mechanical reason this occurs unless they factor in you could use a larger tire, but I doubt that. I like to think it's a way to keep you under the speed limit, even when you think you are speeding.
It's probably a manufacturer decision to have the needle indicate higher than the true speed as a liability protection. If it were set too low, they could be held liable for any speeding tickets issued. If they have it set 2-5 mph high, you can't really claim it's their fault for a speeding ticket. My guess is most manufacturers would do that to protect themselves.

Plus it may be something that helps customers get closer to the indicated mpg ratings (if you're driving slower, you'll get better mpg).
  Reply With Quote
Old 06-13-2009, 09:46 AM   #19
Senior Member
JoeSchmuck will become famous soon enoughJoeSchmuck will become famous soon enough
 
JoeSchmuck's Avatar
Navy: Submarine Launched Ballistic Missiles
Name: Joe
Joined: May 2009, #17443
Location: Virginia
Gender: Male
Posts: 255
JoeSchmuck's Tacoma Gallery
Quote:
Originally Posted by Janster View Post
People were thinking the two (speedo & odo) were two different systems.

They're the same and the info comes off the same sensor.

I was simply trying to say, if one of them is inaccurate...the other one will be inaccurate also (and I'm only talking about actual data in the ECU). I keep forgetting that people only have the needle to use as a reference to compare to. In most cases, that needles isn't accurate to the data in the ECU.
When using my Acutron Scan Tool I can read the ECU data and the MPH data and the needle does not match. In my perticular case, the ODO reads .1 miles less over ~10 miles (a good thing). The needle does indicates faster MPH. These are inverse values. The needle is off and it could be in the D/A circuitry. Just because the needle is off does not mean the ODO is off or even off in the same direction.

Your statement about if one is off, the other will be as well is inaccurate and you're not stating facts but it sounds like you're making up facts.

I'm not trying to offend you but when reading these forums, people don't need others making up facts. If it's an opinion then make it clear.

Now I do agree that most people probably do not have a way to read the ECU so the needle is thier main guide, but the ODO is there too and they can use a GPS or miles markers over a long drive to get an idea of the ODO accuracy.

I also agree the needles are not accurate in most cases but I cannot state a fact they all are.

-Joe
P.S. Damn, you have some nice cars on your website! Wish I could afford the vetts.
  Reply With Quote
Old 06-13-2009, 11:08 AM   #20
Bah Humshit!
brian is one of the sharper tools in the shedbrian is one of the sharper tools in the shedbrian is one of the sharper tools in the shedbrian is one of the sharper tools in the shedbrian is one of the sharper tools in the shedbrian is one of the sharper tools in the shedbrian is one of the sharper tools in the shedbrian is one of the sharper tools in the shedbrian is one of the sharper tools in the shedbrian is one of the sharper tools in the shedbrian is one of the sharper tools in the shed
 
brian's Avatar
Coast Guard: Work and Fly on the Four Fans of Freedom
Joined: Apr 2009, #16011
Location: Roseville, CA
Gender: Dude
Posts: 7,556
brian's Tacoma Gallery
Send a message via AIM to brian
Analog can be inaccurate due to your line of sight on the guage, just because its an 'analog' meter....its still fed by a digital signal. Sure, the needle can be off, or miscalibrated, but in the end its ONE signal.... we've all agreed on that I believe.

Honestly, you guys are reading wayyyy to deep into this. I've personally done my math, and some of your research only backed up my findings. My speedometer is accurate to my odometer.... why? Because I traveled a whole damn tank of gas and compared the simple math between the two. The 'error' is the same between the two. 107/100 is my error (gps to odo/speedo). If your needle is off, thats a whole 'nother issue that you should get resolved at your dealership. It won't be caused by tires. Am I reaching anyone here?

Probably not.... I suck at explaining things.



ONE INPUT....

TWO OUTPUTS.... simple as that.


Also please keep in mind, my 'error' is not going to be the same as everyone elses, I'm running 285's.
  Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Similar Threads
Thread Thread Starter Forum Replies Last Post
help on tires/gearing effect on speedo and odometer NYCO Performance and Tuning 20 12-09-2013 01:41 PM
speedo/odometer not working? kane Technical Chat 9 08-28-2011 06:27 PM
New Tacomas are not created equal? Mikedawn25 South East 4 07-20-2010 02:51 PM


Copyright © 2014 Tacoma Forum. Tacoma World is not owned by, or affiliated with Toyota Motor Corporation.