Rubicon Owners Forum banner

Yellow box wiring - INSTALLED AND ISSUES SOLVED.

2602 Views 24 Replies 5 Participants Last post by  Skinny Pedal
Came today. Best place to tap in and wire colors. Thanks in advance :D
1 - 20 of 25 Posts
Re: Yellow box wiring

Research is what I did but, different yrs have different wire colors and locations in the PCM wire bundles. I placed mine behind the glove box so, you will need to extend the wires to go through the rubber grommet on the driver's side then back across the fire wall on the inside of the engine compartment to the PCM. It is located on the passenger side firewall. You will have 3 wire bundles going into it. For your '03, your wires are in the center bundle. To determine the colors, you will need to crawl under your rig and look at what is coming out of the TC because I do not remember.

Some recommend placing the unit in other locations but, it's whatever "blows your skirt up" as to where you place it.

Make sure you disco your battery and do not use scotchloks. Solder the connections. HTH
Re: Yellow box wiring

Purple with white stripe = +5 volt
Black with lt. blu stripe = ground
White with orange stripe = signal


Those colors ring a bell? Those are from a 2004 Rubi, does it matter if auto or manual?
Re: Yellow box wiring

Nope, I have different colors...
Re: Yellow box wiring

alpine said:
Nope, I have different colors...
Yes "WE" do. I can't remember but, what ever write up I looked at, had the wires in the outboard bundle. So, you can skip that one altogether. I know that it was a later model than '03. No difference in colors with manual or at. You just gotta crawl underneath and remove some tape and wire loom to see the colors. I sent my findings to Josh but, I guess that he hasn't found the time to do a write up.
Re: Yellow box wiring

Do you have a link to the write up by chance?


:::: EDIT::::::

Found one.
Re: Yellow box wiring

Well wired it up.. Don't work. It works when the key is on the run position without motor running, then when you start the jeep it don't work.

I have the FSM in pdf form, and the wires it calls for are

white/orange speed sensor signal
violet/white 5 volt supply
and I'm guessing black / light blue for ground but if you look at the schemtics it turns into pink/yellow after battery temp sensor? Am I missing something here?
Re: Yellow box wiring

I must have gotten a bad one, the speedo reads zero all the time and the yellow box has power as the led's are blinking as it reads the sensor. If I loop the sensor back together my speedo works again. So I'm gonna say it's defective. I've tripled check the connections, used my volt meter to test the wires and it all checks out.

I've wasted 3 hours already and done wasting more. Thumbs down for this product.
Re: Yellow box wiring

I put the box into test mode, the leds blink as if it's recording the speed. I then set it to what I am off 11%, it just don't work. I'm stumped and I noticed when I am shifting it goes off and then comes back on. WTF am I missing?
Re: Yellow box wiring

Sorry I can not be a much help but have you double checked that the wire color at the tcase sensor is the same as by the PCM?


I found some of the install manuals but you probably already have these:
http://www.yellr.com/yb_inst.htm
Re: Yellow box wiring

Yep same colors. About to rip it all out and just say f*ck it. Check engine light popped on, now I have 5 fault codes guessing it fried the pcm. sweet.
Re: Yellow box wiring

Just redid all the wiring, same issues. I just don't get it. I plugged the little plug that comes with it so you can change it from vehicle to vehicle and the speedo works perfect again. Beyond frustrated now. :lildevil:


It has power, I noticed it loses power when I push the clutch in and shift along with when slowing down to a stop. The colors match the pcm and the t-case, they test out as well. So short of a defective unit I have no clue.
Re: Yellow box wiring

It lights up ok, but the speedo doesn’t work… Make
sure it is not in a special test mode. Check you have
connected the YB harness IN (white wire) and OUT wire
(grey, or green wire) the correct way around. Check for
bad connections on these wires. Incorrect connection will
not damage the Yellow Box or damage the speedo.
http://www.yellr.com/yb4_insta.pdf
Re: Yellow box wiring

gregert12 said:
It lights up ok, but the speedo doesn’t work… Make
sure it is not in a special test mode. Check you have
connected the YB harness IN (white wire) and OUT wire
(grey, or green wire) the correct way around. Check for
bad connections on these wires. Incorrect connection will
not damage the Yellow Box or damage the speedo.
http://www.yellr.com/yb4_insta.pdf


Done that... No dice.
Re: Yellow box wiring

Ok.


Wow am I a moron.. I figured it out.

I went straight to the sensor itself tonight and tapped into it there.

Colors for an 03 Rubicon are this.
ORANGE / 5+ Volts
TAN / SENSOR WIRE
BLACK / GROUND

I then fed the harness up my shift boot since I have a 5 spd and went for a drive. It's right on now and everything works, I then zipped tied it all in place and placed the yellow box under my shift boot so it's easy if I need to tinker with it and protects it from the elements.


I'll snap some pics and make a full write up.


I'm thinking part of my issue was that I was grabbing the wires at the PCM, and the running wires all the way to the glove box and for some reason there was just enough drop in volts over the run to make it not work. Sadly, The way I redid it tonight took my 10 mins.. Hardest part was removing all the old wiring. Time for a beer!!!! :laugh:
See less See more
Great idea having it at the shifter.
Your luck on this one is what I usually go through for the simplest of mods. Mine worked perfectly on the first go around. I apologize if, I lead you astray. I don't recall all the '03 wires being solid in color though.

I did spend a large amount of time this afternoon under my heep and should of checked the colors for you. While mounting the box on your shifter sounds like a good idea, I am wondering about the constant movement on the wires and them holding up.

Glad you got it working and I apologize again if, I caused any issues for you.
Worked a few days and then crapped out. Freaked the PCM out, SES light is in now.. :banghead:
Joe you might want to keep the wires as short as possible. Sounds like you might be picking up noise on the sensor wire. You also could try the headlight switch thing to reset the pcm:

Disconnect the + battery cable and touch it to ground for 30 secs.
Reconnect the cable
Turn the ignition switch to on (but don't start)
Turn headlights on
Turn headlights off
Turn ignition key off.
I'll give it a shot, the length of the wires is only 3 feet I believe since that's the how the harness came.
1 - 20 of 25 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top