Yellow Box Speedo Calibrator

The reason for the length is because the ABS ECU is on the right side of the engine, meaning the harness has to cross the engine compartment at the firewall and then still have enough length to go into the cab and be able to set the unit. I got 3 meters and where you see the unit laying just behind the e-brake pedal is as far as it would reach. You could also install this in the cab by removing the gauge cluster and splicing the harness there and use a keyed power and ground inside the cab. I preferred going under the hood because it is easily reversed if I ever go back to a stock tire size. As far as the programming. Yellr can set your correction ratio before they send you your unit so you don’t have to. Also, like you the first unit I purchased was a 2-wire unit. Yellr exchanged it free of charge, so don’t go selling it just yet. They sent me my new one and just asked I send the first one back in the same package as return to sender. They did only exchange the unit and not the harness so you may be stuck with it. What length did you purchase and how is it configured? I ask because you may be able to use it.

 

@04TundraTRD that's some clean work, glad you found a way to make it happen!

 

I ordered the V5 plug and play version, along with 3m of harness. Essentially 4 wires with plugs.

 

The harness is the same for both units. You could try to find the connector to match the PnP or just cut it and use it as is.

 

This is awesome, thanks for figuring it out!!! Bare with me as electrical stuff is not my strong point. It looks like the fuses in my 05 are completely different than the 04 and I have to tap into the key power in the fuse panel under the driver side dash and I need to figure out what pwr fuse is the key power.

I only have 2.5 meters of harness so I will probably just have to extend that with extra wire I have. Before I break it, how do you disconnect the ABS ECU connector? Just push in the side tabs and pull up?

 

I honestly cant remember how the connector is disconnected, but I'll check it out tomorrow. As far as your key power I would check the two fuses listed as IGN on your in cab fuse panel, and with a short harness I would probably do the complete install in the cab. Also, I'm pretty sure that the speedo wire on the '05 is a different color but can still be spliced behind the speedo itself. It is completely up to you though, if you do go under hood you will definitely have to extend the harness. Good luck, and let me know how it turns out. I'll keep an eye on the thread if you have any questions.

 

I figured out the ABS connector, its kind of a cool design. You just press the side tabs and wiggle the white locking part up and it comes right off. I contacted Jennifer and she was nice enough to offer me a new harness, so I will just request 4m. I sent her this thread and she was surprised that it didn't throw a code when splicing the ABS. Your previous post said the speedo wire is white/violet on 05-06, which I was able to find at the ABS under the hood. I do like the idea of doing it all in the cab though.

I will keep this thread updated with photos of my install for all the 05-06 guys out there.

 

I’d sure appreciate a diy for the 06

 

Well, thanks to Neil's encouragement and great detective work finding that the ABS signal drives the speedo, I can now say the Yellow Box works on the 2004 Double Cab auto as well. I did not use exactly the same method--the colors for the double cab at the ABS computer are different, and I could not locate exactly the color I needed. While I was searching, however, I ran across the page in the factory manual that shows the inputs and pin positions for the "combination meter"...i.e. dash cluster. I was able to determine that plug "C", pin #2 was the wire feeding the signal to the speedo and tapped there. Too easy!

Power is from the dash fuse panel, since the 04DC has the power outlets fused there. Used a fuse doubler in the power outlet slot and connected to the red wire on the Yellowbox harness (V5 with the prewired harness, but I cut the plugs off the transmission end)

Next, the black wire is grounded to a metal screw beneath the kick panel--the box will rest here as well, after programming.

Now, pull the cluster, and carefully unplug the 4 plugs connecting the wire bundles. You want plug C, which is the second from the passenger side.
Locate the wire from pin #2 (ignore that white wire, it is the Yellowbox harness, just snuck into the picture), in my case, blue with a white stripe and two silver rings. Cut the wire, leaving enough room for your connectors. The white wire from the Yellowbox will take the input form the ABS computer to the Yellowbox, the blue wire feeds it back to the speedo plug.


Boom, just like that, Bob's your uncle. Now just follow the programming directions, seal everything up, and enjoy a calibrated speedo.


For the 2005 and 2006 Double cab, there were changes to the speedo cluster, but I'll bet it is very similar. The 05/06 FSM should show the correct pin and input.

 

Cody, see the post above. I'll bet we can figure this out.

 

I just saw it. But as ‘smart’ as I am. I can’t follow wiring diagrams so I may just pass on this whole thing.

 

Cody, have you had your cluster out of the dash? Is it two plugs? I believe the speed signal comes from pin A24--at least according to the 05-06 FSM.

 

No I haven’t on this truck

 

Great write up man. I’m glad to see you were able to adapt it to work on the DC. With a little teamwork we’ll get Cody going too.

 

I love this kind of innovation.

 

I’ll be out of pocket for most of the day. If I have some extra time tonight I’ll dig into my ‘06 FSM and see about your harness Cody.

 

You’re amazing. I’m not stupid but I only know enough about wiring to get me into trouble.

 

I understand where you're coming from. I've been an equipment tech now for 3 years and it's helped me be more confident in my skills when it comes to the electrical troubleshooting and repairs. Especially when it comes to reading wiring diagrams. I'm attaching some PDF's of the relevant wiring diagrams and the combination meter connectors. It appears that the Speedo gets its signal from Pin 24 on Connector A at the combination meter. It should be a Violet w/ White Tracer Wire. Let me know if you have more questions.

 

Just ordered this today for my 01 4x4.

Thanks for the write-up!!

 

@seth419 Hey, man. Do you have an update? I have a 2006 DC autotrans with the same issue after regearing and bigger tires.

 

Is there any other way other than the yellowbox to calibrate the speed by programming the ECU, chipping it, or someone that makes a sensor that calibrates the speed correctly?

Just to be clear, the 05-06 guys get their speed off the ABS?

 

No update yet. Jennifer said it might take a couple weeks with all the Covid stuff and Yellowbox being in Australia. I am going to try the A24 pin behind the cluster route and I'll be sure to post detailed info/pics here!

As far as I know there is no way to program the ECU or a chip that will allow you to calibrate the speed. Yes, as far as I know 05-06 gets speed from ABS sensor.

 

Thanks, I'm still waiting for an answer to my email that I sent out yesterday. It blows my mind, that it being 2020 nobody has found a solution to this problem.

 

Unfortunately Toyota locked up the programming on the Gen 1 tighter than Fort Knox. The only way that I have found thus far is by using the yellow box or a similar style calibration module. And, yes, on the ‘05 and ‘06 the signal for the speedo comes from the ABS ECU.

 

So on the 06, to get to speed it comes from the ABS? Do you mean the ABS sensor on the spindle's hub?

 

There are 4 wheel speed sensors for the ABS System. The ABS ECU takes those signals and translates them into a single pulse signal that is then sent to the speedo. The yellow box intercepts that signal, and adjusts the pulse based on your correction ratio ( ie. my speedo read 73 MPH while my actual GPS verified speed was 80 MPH - my correction ratio is 09125), now my speedo is dead nuts. It’s a fairly straight forward install and there are some great guys on this forum that are willing to help you through any issues you have.

 

I wish the yellow box worked for us 06 guys. So what if I disconnected all 4 ABS sensors? Would that trick the system, thinking the sensors went bad?

 

Lol. I would think you’d have no signal coming in then and your speedo would show zero

 

Maybe stop the odometer for better resale

 

I'm about to find out! hahaha