Yellow Box Speedo Calibrator

I recently stumbled across something in a land cruiser forum that got me excited. YellR, a company which makes the Yellow Box speedometer calibration device, had built a plug and play version to work on the Aisin transmission.

To my knowledge this has never been available for our trucks, everyone who I have seen install a calibration device had to either solder into the wires at the sensor or solder in the wires behind the speedo.

I took a good look at the plugs on that land cruiser model and figured they were the same as the speed sensor on my transmission. I reached out to YellR by email to ask if it would work, they were confident that it would. Ordered one up with 2 meters of harness and crossed my fingers. $110.85 and around 2 weeks later it arrived.

First thing I did was carefully remove the wire leads from the plastic plug which connects to the Yellow Box. There is a special tool for this but I went in with a good safety pin. I then went under my truck with a mouth full of zip ties and a clipper.

Disconnected the plug on the vehicle speed sensor, observed how it was binding on another wire loom and tucked it to the other side of that loom. Then I plugged in the Yellow Box harness, it just goes between the factory harness and the speed sensor. It's fairly idiot proof and took a bit of pressing to click in place. Gave the plugs a tug to be sure, then started looking for a route. I used some 3/8" plastic tubing to shield the harness, I may at some point insulate it with heat proofing since it passes near the header flange, but I was able to route it a reasonable distance from the hot stuff. I tied the harness to another harness every foot with a zip tie and went up the firewall and under the master cylinder, then pushed the wire leads through the grommet next to the fender.

The wire leads popped through near my parking brake pedal, I inserted them back into the plastic plug and made sure they were seated well. Plugged that into the Yellow Box and turned on my truck.

I saw the red and green lights flash, then the red one began flashing codes at me. It uses a series of quick and long flashes to let you know what it is set to. When you drive it flashes green then stays green until you slow down. I did the math and knew my speedo was around 9.6% faster than actual speed, verified by GPS. To calibrate, I parked the truck with the motor running and held both buttons down until they flashed a few times. Then held the red + button until it flashed about 10 times, then went for a drive.

I verified that I was getting closer to correct by driving with a GPS speedo on my phone, went to park after a bit and made further adjustments. After about 3 rounds of this my speedo is now dead on, I double checked by driving through a speed checking sign at 45 mph, perfect. I tucked the box behind the kick panel so I won't get distracted by the flashing lights.

If you want your speedo corrected I strongly recommend getting this. It's significantly cheaper than the only other option I have seen and the install is way easier.

I might have been better to ask for 2.25 meter length harness, that would have been perfect but I got what I needed out of 2 meters. Took me about 30 minutes to run the harness and plug it in, another 30 to get the calibration right.

Order here, make a note in the comments that you need 2.25 meters of harness. Great company and great customer service, Jennifer was very helpful for me.
https://www.yellr.com/

 

Wow. Good info. You sir, are a gentleman and a scholar.

 

Fantastic. Added to the must have list.

 

Disclaimer! I have heard that these may not work on 05-06. Check with Yellrbox if you have that model.

 

Darkness, thanks for the post. I just bought a Gen 1 myself and have been searching for hours and hours for a fix. I just ordered the Yellr myself but I'm curious if you had to do anything with that unused pigtail on the Yellr harness in your pictures? Does it just stay open like that, or is there another connection to be made?

 

@BlueAces96 if you mean the 3rd picture down, I took a pic right before plugging that in. There is a male and a female on the yellr, when completed theyll both be connected to the original harness. This pic is as I clicked it into place.

 

Nice write up, on my todo list.

 

Darkness, clearly not COMPLETELY idiot proof!!! Thanks man!!!

 

Not sure why I posted the unconnected pic, either way it's been good so far.

 

Note to anybody interested with a 4WD 04 or older, ask for 2.5 meters of wire harness. Installed one today and the speed sensor is on the rear right side of the transfer case, takes about an extra foot but an extra 18" would give options for wire routing.

 

Bumping this old thread. It looks like you ordered the plug n play version? I'm going to have some questions on this. Does it come with a set of decent instructions as well?

 

Yes, that's it. Actually ask them for 3 meters of harness just in case, they don't charge extra for it. When you order there is a box for comments, put the comments there. I would also get about 6 feet of that plastic wire conduit from Autozone or similar, the corrugated one.

They don't send install instructions but I can walk you through that. They do send instructions for how to do the calibration, they're not easy to follow but I can tell you about that too.

If you crawl under your truck, look at the back of the transfer case. You should see a plug there on the case near a cross member, that's the speed sensor. The harness they send will have a male and female plug, wipe the plug on your case to get dirt or mud off and gently unplug it. Your harness will plug right in, be sure it clicks on both ends. Then you put that plastic wire conduit over the harness wires, grab a lot of good zip ties and start running the cable. Stay clear of exhaust and moving parts.

You'll want to go along that cross member and up the inner frame, you'll see something there to follow and attach to. Run the wires up from the frame to behind the brake booster on the driver side. Look around there and you'll see a big rubber grommet with a wire loom running into the cab, carefully cut a slit in that about an inch wide and shove the harness end through. Go in the cab and find it bear the parking brake pedal, connect the box and pull any slack into the cab.

Then you're ready to calibrate. It's really an easy install, took me 30 minutes in a parking lot on my truck. Took me a little longer on a Sakana's truck here because I'm not as familiar with 4wd.

 

Will this work for a 2018 Platinum?

 

I would reach out to Yellrbox to ask that. Very friendly and knowledgeable staff.
staff@YellR.com

 

Nice write up. I remember being damn near the first to use one of these on a 1st gen Tacoma 10 years ago.
Glad to see they have a plug n play version now.

 

Thanks @Scuba I'm glad they have it because my soldering skills only apply to copper pipe, I suck with wires.

 

Luis, everything still working well with the box? After putting on the 285s/70s I'm 7-8% faster than the speedo according to the GPS

 

Yup, no problems here.

 

Ordered!

 

I have a sneaking suspicion this isn't going to end well...looks like the 2004DC uses a different speed sensor (two wire instead of 3) so the plug and play harness is not going to work.

 

Really? Is it a different part number? You arent looking at a wheel speed sensor right?

 

Don't believe so. It is a two wire unit on the driver's side of the transmission. The control unit on the back of the transfer case has 3 plugs, 2 two wires and one six wire.

 

And all my online searches show the vehicle speed sensor as a two wire inductive pick-up. The 2004 DC really is a bastard stepchild

 

Yeah I just looked around, the interesting part is that 2 wire is also listed for some access cabs. Really unusual that Toyota would do that. Sorry man, wonder if theyll accept return, or if not you could sell it here.

 

No worries, kind of getting used to it with the DC. I've contacted them about possible splicing or a different harness or will sell it. Can't imagine shipping it back to AUS would be cost effective.

 

Just an FYI if this helps any, this is my correspondence with them and I've attached the pics they sent in an e-mail. I know you have a different transmission but it seems you have the same connectors of the A750F even though you have an A340F....? I didn't pursue it since I have my Torque app running all the time on my HU with a big MPH.


Hello,

Are you able to check the Output Speed Sensor type, located on the
transmission. If like attached photos, then yes, Yellow Box v5 is
compatible. If has same 3-pin plug set then Plug-n-play Harness is
available. For a "2-wire" sensor it will be Splice Harness only and
require Yellow Box v5 "2-wire" unit.

Thank you.

Best regards,
jennifer

Yellow Box Speedo Recalibrator - Correcting speedometers worldwide since 1999.
website: www.YellR.com
email: staff@YellR.com

----- Message from XX <XXXXXXXXXXXXXX@yahoo.com> ---------
Date: Fri, 7 Feb 2020 14:38:27 +0000 (UTC)
From: XX <XXXXXXX@yahoo.com>
Subject: Compatible with 2006 Toyota Tundra?
To: staff@yellr.com


> Do you have a version that will work with my 2006 Toyota Tundra?
> The Transmission
> is an Aisin A750F.
> Thanks!

 

I thought the 04-06 DCs had like 6 inputs for the speed and was unable to get a yellow box to work???

 

Cody, not sure about the 2005-2006. There are definitely two different speed sensors on the 2004, a VSS 1 and VSS 2. One is a 5 or 6 wire plug on the transfer case, the other is the two wire sensor shown above in Speedtre's post. I'm not entirely sure the Yellr box will work to recalibrate with only the two wire. Still trying to research. Yellr has offered to exchange the boxes with me for the two wire--entirely my fault for assuming the 2004 DC had the same connectors as the 2004 regular and access. I now have a service manual to check such things before I screw up.

 

Have you had any luck with this? I'm in the same boat and was hoping to find a solution. I tried connecting my yellowbox using the two wire solution by intercepting the signal coming from the ABS ECU but all it seems to accomplish is to kill the speedo.

 

I only see two 2 wire switches on the back of my transfer case.

My truck is a 04 4x4 AC