Speedo/Odometer recalibration for larger tires?

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r2m

r2m

Richard
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This is for my 2013 GX 460, premium with navigation.
So in my search for recalibrating my speedo/odometer for my 34.9" O.D. tires, I can't find anything in our 150 series forum. Even in ClubLexus I can't really find anything difinitive.
I'm looking for a:
  • hack
  • add-on module (any products?)
  • going through the on-screen display
  • or??
My speedo is about 9.5 percent off. At 60 mph on the dial on the dash, my phone's GPS reads 65 mph.
 
HitchCrack said:
I have been told you can have scan gauge display the correct speed based of new tire size. I have a SG but haven't played with that part of it yet.
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Wouldn't just using a GPS app on my phone work and be the same thing? I have a great wireless charging mount for my Galaxy Note 8 that I could use.

But it would still be nice to have the O.D. be correct also. I re-geared my GX when I added the lockers and that didn't correct the speedo.
When I put 35" BFG M/T's on my 1998 Landcruiser, it was all wacked out also until I added the front locker and re-geared the front and rear diff's. Then at 70 mph on my speedo, my actual GPS speed was about 68 mph. I was able to live with that.
You can find photos of my LC on the 100 series forum, if interested. ;)
 
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I wouldn't recommend this just for the speedo function, but the ARB Linx product includes a speedometer function. If you are looking for an all-in-one product for controlling lockers, accessories, and also correcting speedometer you might want to check it out. Home - ARB Linx - Vehicle Accessory Interface
 
TX GX460 said:
I wouldn't recommend this just for the speedo function, but the ARB Linx product includes a speedometer function. If you are looking for an all-in-one product for controlling lockers, accessories, and also correcting speedometer you might want to check it out. Home - ARB Linx - Vehicle Accessory Interface
Click to expand...
Just checked out your link. Very cool!
Just checked out the price. Very expensive!
 
r2m said:
This is for my 2013 GX 460, premium with navigation.
So in my search for recalibrating my speedo/odometer for my 34.9" O.D. tires, I can't find anything in our 150 series forum. Even in ClubLexus I can't really find anything difinitive.
I'm looking for a:
  • hack
  • add-on module (any products?)
  • going through the on-screen display
  • or??
My speedo is about 9.5 percent off. At 60 mph on the dial on the dash, my phone's GPS reads 65 mph.
Click to expand...

This is what you're looking for:

Universal Speedometer Signal Interface

I have used this successfully when I swapped in a chevy motor into my mazda. I had a friend drive my car while I was holding a GPS device while I programmed the unit with my speedometer. You will need to track down the speedo wire and splice into it.
 
LTSR said:
This is what you're looking for:

Universal Speedometer Signal Interface

I have used this successfully when I swapped in a chevy motor into my mazda. I had a friend drive my car while I was holding a GPS device while I programmed the unit with my speedometer. You will need to track down the speedo wire and splice into it.
Click to expand...
This looks very promising!
But... I need a FSM that shows where all the wiring is. I don't want to be Willy-Nilly cutting and splicing wires and fry my computer or electrical. I'm a mechanical engineer and so I just get by with electrical.
I found one FSM but it is not really a "how-to" type of manual.
If anyone out there knows where to get a PDF of a thorough FSM, feel free to drop a link or post a copy!
 
PoindAxster said:
@r2m - what did you end up doing?
Click to expand...
I use a couple of methods:
  1. If I'm needing directions or on a long trip and just want to keep track of time to destination, I use the Google Maps. It provides both the "Posted Speed" and my GPS speed, which I really like when traveling through area's when I don't know the speed limit of the road I'm on.
  2. Or, use the OBDLink app when I also want to monitor all my engine systems.
  3. And sometimes just a very simple GPS speed app.

So the short answer to my original post and your question is, no, I have not been able to find anything that will calibrate our speedo's.
 
Okay. I was hoping there was an answer out there. I’m using the Garmin Tread and a Radar Detector with GPS connection to get a more accurate speed reading.
 
On my 470 I used a SpeedoHealer. It is spliced into the vehicle speed sensor (VSS) wire that runs into the back of the instrument cluster. It works perfectly and corrects the speedometer, odometer, and MPG monitor (as all of those are downstream electrically of the instrument cluster). If someone can get a FSM for a GX460, it should be possible to see if it is set up the same way. If the wiring diagram for the cluster can be posted, here, I'd be happy to compare it to the 470 diagram and opine on if it might or might not work. It was not hard to pull the instrument cluster, cut the input wire, make two splices, and then run the wiring (including +12V and ground) to the SpeedoHealer. Total cost was around $130.
20240106_180208.webp

20231227_173822.webp
 
Rednexus said:
On my 470 I used a SpeedoHealer. It is spliced into the vehicle speed sensor (VSS) wire that runs into the back of the instrument cluster. It works perfectly and corrects the speedometer, odometer, and MPG monitor (as all of those are downstream electrically of the instrument cluster). If someone can get a FSM for a GX460, it should be possible to see if it is set up the same way. If the wiring diagram for the cluster can be posted, here, I'd be happy to compare it to the 470 diagram and opine on if it might or might not work. It was not hard to pull the instrument cluster, cut the input wire, make two splices, and then run the wiring (including +12V and ground) to the SpeedoHealer. Total cost was around $130.
Click to expand...
That's a great idea! Hopefully, someone has that diagram.
 
PoindAxster said:
That's a great idea! Hopefully, someone has that diagram.
Click to expand...
Someone may need to get a 2-day login for Toyota TIS ($30) and buy an electronic copy of the Techinfo/FSM. Luckily for the 470, there is a 2005 FSM .pdf floating around on the web. I've downloaded it and have it saved in multiple locations. It's like 3,000 pages long but has been invaluable for working on my rig.
 
Rednexus said:
Someone may need to get a 2-day login for Toyota TIS ($30) and buy an electronic copy of the Techinfo/FSM. Luckily for the 470, there is a 2005 FSM .pdf floating around on the web. I've downloaded it and have it saved in multiple locations. It's like 3,000 pages long but has been invaluable for working on my rig.
Click to expand...
The download is still going on my machine, but here's a link to one @r2m supplied years ago: GX 460 Manuals - https://forum.ih8mud.com/threads/gx-460-manuals.1129713/#post-12262869
 
PoindAxster said:
The download is still going on my machine, but here's a link to one @r2m supplied years ago: GX 460 Manuals - https://forum.ih8mud.com/threads/gx-460-manuals.1129713/#post-12262869
Click to expand...
I think you can do it. Looks like the GX460 cluster receives the speed signal from the skid control ECU via pin G3-33. The signal going into the cluster (note the FSM calls it a "combination meter") is listed as Wave Form 1 in both the GX470 and GX460 FSMs, with the form of the wave being identical in both FSMs. Vehicle speed then comes out of the combination meter and goes to the ECM and multiple other systems - so I think correcting the signal going into the combination meter at G3-33 has a good chance of also correcting the odometer and MPG meter. So, it appears that you could snip the wire leading to pin G3-33, splice in the SpeedoHealer, and be in business just like a GX470. I would suggest powering the SpeedoHealer from a ignition-on fuse tap in your interior fusebox and grounding it somewhere else on metal, as opposed to splicing into the power/ground wires that lead into the combination meter (as there is limited room to splice/work behind the cluster and the cluster wires are pretty thin). The actual SpeedoHealer can be mounted wherever you wish.

BUT, I have not tried this, so don't get mad at me if it does not work on your GX460, verify that the diagrams are applicable to your year of GX460, perform at your own risk, and be ready to repair wires you cut if you screw it up :). Also note that you need to be super careful in interpreting the FSM - it has multiple diagrams and not all are clear if you are looking at the female connector on the rear of the combination meter, or the male plug behind it. So, double-check the wire color before you snip anything (the 470 FSM is clear on wire colors, while the 460 FSM appears to list them in the "wiring diagram" section rather than in the diagnostics section)
GX460 FSM Excerpts:
gx460_terminals.webp


gx460_key.webp

gx460wf1.webp

GX470 FSM Excerpts:
gx470_terminals.webp

gx470_key.webp
 
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GX470 FSM Excerpts (Continued):
gx470_wf1.webp
 
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Wow! That's some great detective work! Columbo would would proud! 😁
Seriously, that's was pretty good finding that. Now, because that product is only for motorcycles, figuring out how to translate SpeedoHealer to a GX460?
 
r2m said:
Wow! That's some great detective work! Columbo would would proud! 😁
Seriously, that's was pretty good finding that. Now, because that product is only for motorcycles, figuring out how to translate SpeedoHealer to a GX460?
Click to expand...
To be fair, the original idea is not mine - it's that of another forum member documented in this post :). I'm not sure I would have figured out a GX470 install on my own, and I actually spliced the wrong wires when I first attempted it, so I got to know the process well, and am happy to help folks try and also shoehorn one into their 460s. If it works, maybe call it the "Rednexus speedometer mod"? :)

Regarding the part, it seems that most vehicles use a consistent type of speed signal. Although they market it for bikes and UTVs, it definitely does work perfectly in my 470, and the FSMs show the signal to be the same with the 460. It's not plug and play (I'm not sure it would be possible to make a plug-and-play module), but a speed signal does appear to be a speed signal.

For my install I purchased the SpeedoHealer and a generic harness from Bayside Performance (see part numbers below). I'd suggest using heat-shrink connectors, like these 22-26 ga ones, and heating them up with a small propane torch with a heat shrink attachment (I have a Master MT-80K), as opposed to a heat gun, in order to avoid indiscriminately cooking other things behind the dash when you make the connections.
Screenshot 2025-11-05 104400.webp
 
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