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Discussion Starter #1
I have oversized tires on my RAV4.1 Ay Caramba and my speedometer was about 10% below my actual speed and I needed a solution. After a lot of research I found something that works, the Yellow Box V5 and it's so simple to make it work. And, the good news is that when you get new tires or as they wear you can adjust the calibration. Another benefit is that it can adjust for larger or smaller tires and works on just about any vehicle that uses an electrical speedometer.

You can order it with the right connectors to plug into the vehicle speed sensor and then the RAV4's wiring plugs into that or if you are more adventurous, you can hardwire it into your system. Then all you have to do is calibrate it by following the easy procedures, then take it for a test run, fine tune it and you're done. The Yellow Box has to stay connected for it to work, and you can keep it in the engine compartment somewhere out of the way or do what I did and run it into the cabin.





https://www.yellr.com/ordering.htm



 

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Discussion Starter #2 (Edited)
Procedures for the Yellow Box v5

The instructions are not too good so here's how I installed and calibrated the Yellow Box V5.

Installation
1) Disconnect the VSS
3) Add some dielectric grease to the connectors
4) Plug in the Yellow Box into the VSS cable and then into the VSS.
5) I cut the wire and passed it through the firewall on the left side where the wire bundle passes through. This isn't necessary, you can merely secure it in a safe place under the hood, I put it in the cabin to protect it better from heat, chemicals, and moisture.
6) I put a length of shrink wrap over the wires.
7) I spliced the wires back together using marine grade butt splices and used a heat gun to shrink the splices, pulled one of the shrink wraps over the splices and applied heat.
8) Test the connection, turn the key to on and observe that the Yellow Box goes through it's startup.

Computing speedometer error
1) Using a Bluetooth OBDII scanner and my phone with the Torque App
2) Under "Realtime Information", go to to a blank page or a page with room for a new gauge
3) Then go to "Add display"
4) Go on to "Digital Display"
5) And finally select GPS vs OBD Speed difference", select a size that is easy to read with the phone/tablet sitting where it can get a clear view of the sky and where you can easily read it.
6) Now it's time to take her out for a drive, I recommend going relatively fast, I ran up to 60 mph where it said I was 6 mph over. If you have undersize tires this will be a negative number.
7) Easy computation time 6 is 10% of 60 so I'm going 10% faster than the speedometer reads.

Calibrating the Yellow Box v5
1) Turn the car key to on, lights will flash on the Yellow Box
2) Now push both buttons down at the same time and hold for about 5 seconds when the lights will flash letting you know it's in learning mode.
NOTE: Holding the + or - button (one at a time) adds or subtracts 1% per flash and clicking the button changes the speed by 0.1% with each click.
3) Because I was over I need to push and HOLD the - button while observing the number of flashes, I stopped at 9 so that I could fine tune it.
4) Turn the ignition off
5) Take it for another drive, now it ranged from 0 to 1 mph over.
6) I stopped the car turned it off, waited a few moments and then turned the key back to on without starting the engine.
7) Once again it flashed
8) Again I held both buttons for 5 seconds and it flashed again that it was in learning mode
9) I then CLICKED the - button 5 times
10) Turn the ignition off
11) I took it out again to verify the speed and it stayed at 0 except for occasional deviations which is to be expected.

That was all there was to it and now I know exactly how fast I'm going when looking at the speedometer.
 

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Discussion Starter #3
I found a problem I initially synched up the OBDII speedometer and the GPS but not the dash speedometer. The dash speedometer reads 2 mph faster at 60 mph than the OBDII, I adjusted my Yellow Box to make the GPS and the dash speedometer the same so all is well in the world.

So a new recommendation on that blank page that we added to Torque, add "Speed (GPS)" and "Speed (OBD)" as well so that you can compare all the relevant settings. Also of course look at the dash speedometer to get everything calibrated properly.
 

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The instructions are not too good so here's how I installed and calibrated the Yellow Box V5.

Installation
1) Disconnect the VSS
3) Add some dielectric grease to the connectors
4) Plug in the Yellow Box into the VSS cable and then into the VSS.
5) I cut the wire and passed it through the firewall on the left side where the wire bundle passes through. This isn't necessary, you can merely secure it in a safe place under the hood, I put it in the cabin to protect it better from heat, chemicals, and moisture.
6) I put a length of shrink wrap over the wires.
7) I spliced the wires back together using marine grade butt splices and used a heat gun to shrink the splices, pulled one of the shrink wraps over the splices and applied heat.
8) Test the connection, turn the key to on and observe that the Yellow Box goes through it's startup.
Just saw your post and this looks very interesting. I have a 2008 RAV4 V6, which originally came with 16" wheels. I changed to 17" and the speedometer reads slow by 6-7%.
In your installation notes, where exactly is the VSS cable that you disconnected in Step 1)?

Thanks,
Mike
 

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The instructions are not too good so here's how I installed and calibrated the Yellow Box V5.

Installation
1) Disconnect the VSS
3) Add some dielectric grease to the connectors
4) Plug in the Yellow Box into the VSS cable and then into the VSS.
.
Where did you disconnect the VSS cable? Is the sensor on the top of the transmission just under the battery tray?
 

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A great find!

I plan to get the splice version, a little cheaper and I can keep it all under the dash without having to do anything under the hood.
 

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Discussion Starter #7
Please provide your year, model, and transmission. Where are you from, left or right hand drive?
 

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Discussion Starter #8
Where did you disconnect the VSS cable? Is the sensor on the top of the transmission just under the battery tray?
This is where the VSS is on my 99 RAV4, manual transmission, AWD as seen from the rear of the engine.

 

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Discussion Starter #10

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Discussion Starter #12
Revised procedures, I left a step out and included all the gauges I added to the Torque app. The underlined are the main things I changed and here and there I cleaned up the wording a little.

The instructions are not too good so here's how I installed and calibrated the Yellow Box V5.

Installation
1) Disconnect the VSS
3) Add some dielectric grease to the connectors
4) Plug in the Yellow Box into the VSS cable and then into the VSS.
5) I cut the wire and passed it through the firewall on the left side where the wire bundle passes through. This isn't necessary, you can merely secure it in a safe place under the hood, I put it in the cabin to protect it better from heat, chemicals, and moisture.
6) I put a length of shrink wrap over the wires.
7) I spliced the wires back together using marine grade butt splices and used a heat gun to shrink the splices, pulled the shrink wrap over the splices and applied heat.
8) Test the connection, turn the key to on and observe that the Yellow Box goes through it's startup.

Computing speedometer error
1) Using a Bluetooth OBDII scanner and my phone with the Torque App
2) Under "Realtime Information", go to to a blank page or a page with room for a new gauge
3) Then go to "Add display"
4) Go on to "Digital Display"
5) And finally select "GPS vs OBD Speed difference", "Speed (GPS)", and "Speed (OBD)". Select a size that is easy to read with the phone/tablet sitting where it can get a clear view of the sky and where you can easily read it.
6) Now it's time to take her out for a drive, I recommend going relatively fast, I ran up to 60 mph where it said I was 6 mph over. If you have undersize tires this will be a negative number.
7) Easy computation time 6 is 10% of 60 so I'm going 10% faster than the speedometer reads. Make sure you are observing the speedometer speed as well as the other comparisons, I matched the speedometer speed to the GPS speed which was 2 mph over what the OBDII speed read.

Calibrating the Yellow Box v5
1) Turn the car key to on, lights will flash on the Yellow Box
2) Now push both buttons down at the same time and hold for about 5 seconds when the lights will flash letting you know it's in learning mode.
NOTE: Holding the + or - button (one at a time) adds or subtracts 1% per flash and clicking the button changes the speed by 0.1% with each click.
3) Because I was over I need to push and HOLD the - button while observing the number of flashes, I stopped at 9 so that I could fine tune it and waited a few seconds until both lights flashed indicating the change was saved.
4) Turn the ignition off
5) Take it for another drive, now it ranged from 0 to 1 mph over.
6) I stopped the car turned it off, waited a few moments and then turned the key back to on without starting the engine.
7) Once again it flashed
8) Again I held both buttons for 5 seconds and it flashed again that it was in learning mode
9) I then CLICKED the - button 5 times and waited a few seconds until both lights flashed indicating the change was saved
10) Turn the ignition off
11) I took it out again to verify the speed and it stayed at 0 except for occasional deviations which is to be expected.

That was all there was to it and now I know exactly how fast I'm going when looking at the speedometer.
 

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Discussion Starter #13
So I've been using the Yellow Box V5 for a about a month so here is my review and final changes.

I decided to split the difference between the speedometer and the OBDII speeds so, now my speedometer reads 1 MPH faster and the OBDII is 1 MPH slower than GPS speed. I did this because I use a NAVDY GPS which displays the OBDII speed on a HUD display and I wanted the displayed speed to be as close to the speedometer speed as I could get. I wish there was someway to tune the speedometer and OBDII to match short of bending the speedometer needle (if it bends).

The Yellow Box V5 has not had any issues and continues to work as designed.

The Yellow Box indicator LEDs flash during diagnostics and again showing calibration; at night the flashing is noticeable but not detracting.

It will pay for itself by keeping me from speeding tickets because my speedometer reading was 10% slower than actual speeds (caused by my oversized tires).
 

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My Yellow Box finally arrived. Got it installed and calibrated yesterday.

Already I like not having to translate when I check the speed, now I just need to get use to the speedometer being accurate.

I spliced into the wiring harness by the IG2 connector, a dark gray connector sitting right above the ECU, a red wire with a yellow stripe going to pin 10. This kept the whole installation to the lower part of the center dash area and it is easy to store and access the yellow box behind the double-din face-plate. Since the splice kit starts with a bare cable at the one end, I slid the loop of the by-pass jumper over the cable, now the jumper hangs on the cable near the yellow box.

Thank you for the write-up, your instructions really helped.
 

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Discussion Starter #15
Kool, I'm glad it worked for you. I like the way you installed it, I should have wired it in like that.
 

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Discussion Starter #16
An update on the Yellow Box V5 Electronic Speedo Recalibrator that I installed in July 2018. It is still working great, I really like have my speeds match as close as possible.
 
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