Accurate Speedometer…Finally

Posted: July 18, 2025 | Author: Rubicon Ronin | Filed under: Uncategorized | Tags: speedometer, yellow box | Leave a comment

For those regular readers, you’re familiar with my recent trail Jeep saga. Transmission went out (violently) and that took out the engine. But I’m back on the road, I mean trail.

Since I bought this Jeep in August of 2019, a 2006 TJ Rubicon, the speedometer has read high, about ten percent. I figured I’d try to get the speedometer to read a little closer. The Jeep had stupid low mileage, less than 21k, and I wanted to keep it low.

I can’t remember what I looked into back then, but I ended up ordering a “Yellow Box” out of Australia. I must have realized that the Rubicon model has an electronic pick up for the speed sensor not a gear driven sensor. So, no simple gear swap.

So, I ordered it up in 2019 and read the directions. It required cutting into the speedometer wiring and splicing in the unit. Rather than doing this under the Jeep at the speedometer sensor, where it was susceptible to water, dirt, mud, etc., I wanted to trace the wires back to the engine compartment and splice it in there. But the wire loom coming into the engine compartment has like 100 wires!

I put the Yellow Box on the shelf and figured I’d get back to it. I didn’t.

Six years later, I blew up the engine and trans. I figured this would be the time to get the speedometer reading correctly.

Because I’m running an Nth Degree lift kit, my rear suspension is actually a three link. Yes, a three link. At the front there is one connection to the frame. It’s right in the way of the speedometer sensor.

But I pulled the sensor, spliced in the Yellow Box and replaced everything. I soldered the wires. I tightly wrapped the connections individually with electrical tape, twice. I took the time to do it right.

It didn’t work. For those of you that don’t know, I have an electronics background. I can still read a basic schematic. I can solder wires. I was frustrated. I took it all apart and everything seemed correct. I double checked all the wiring and put it back together. It still didn’t work.

Rereading the directions and their website, again and again, I came across this…”We can only provide a small amount of tech support time per customer, so please check your installation carefully!” I reached out anyway.

My email was titled “Help…I messed up.” I confessed to ordering their Yellow Box years ago but I swear I wired it correctly, and it still doesn’t work. At the time, the 2-wire unit was the only one available.

Jennifer at Yellow Box could not have been a better customer support person. She sent out more technical documents, photographs, updated installation instructions, troubleshooting steps, etc. Many emails were exchanged.

Nothing worked.

She volunteered to send out a plug-and-play unit. I knew that I had wired it correctly, but I used it anyway. And at this point, I had cut and soldered the wires between the sensor and the plug so many times that I ordered a new speedometer sensor.

So, new sensor, new wiring…still didn’t work.

She ran me through one last set of testing, and with my electronics background I was able to send her the details of my step-by-step testing. Still nothing.

It turns out the older 2-wire Yellow Box will not work with my Rubicon model. So, I returned the older box, bought six years ago, and Yellow Box sent me a brand-new current model. This model is much easier to configure once installed.

Success!

The latest Yellow Box could not be simpler to install and configure with the plug-n-play wiring harness. The instructions have thousands of settings to dial in your speedometer to the exact ratio you need to get an accurate speedometer.

I fully recommend Yellow Box for calibrating your Rubicon speedometer, or any speedometer for that matter. The 2006 Rubicon is an odd duck with an older computer but newer electronic speedometer pick-up. I looked into aftermarket ‘power chips’ that allow you to adjust many things on the stock computer. They would not work. I went to my local speedometer shop and he couldn’t do anything. I went to my local speed shop to reconfigure the computer, nope. I even asked at the Jeep dealership. No luck.

Yellow Box worked.

Customer service in America has been on the decline for years. Nobody seems to want to do their job, especially in the service industry. Yellow Box has the best customer service I’ve ever experienced. Customer service in Australia lives on. Jennifer put in more time than she probably should have, and I very much appreciate that.

Thank you again, Jennifer!

For the record, Yellow Box has not asked me to do this. I was not compensated for this although I did get the ‘plug-n-play’ harness at no charge. This is an honest recommendation for an awesome product and company.

If your speedometer is off and you want it accurate, get in touch with Yellow Box…

https://www.yellr.com/

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Rubicon Ronin

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For those 3-link non-believers…

Two regular arms off the axle. The diff skid plate actually has an arm that goes forward to the crossmember. There is a trackbar on the backside from the passenger side of the frame to the axle behind/above the diff. Nth Degree even installed new upper coil spring cups to relocate the top of the spring for the best possible angle for improved flex without binding.

Unfortunately, Nth Degree is no longer around. Replacement parts might be hard to find.

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