Yellow Wire Mod V.2 4LO TRAC

After studying this topic for quite a while, I figured I'd make a post regarding this mod. Before I begin, I just want to state that doing anything to your vehicle is at your own risk, I am not responsible for your actions. Also want to state that the photos in this post are compiled from the original YWM (yellow wire mod) thread and other members. I have cropped and added labels to some. I am NOT the original founder of this mod. I'm just trying to hopefully clarify the older post with what I feel is accurate.

This is a modification for NON OFF ROAD TRIM 2nd gen trucks without ATRAC. This mod is to achieve TRAC controls in 4LO while in 4WD which allows the breaking system to limit wheel spin to lost traction wheels to give more power to wheels with traction. All 4x4 3rd gen trucks have 4LO TRAC controls but they did not advertise this. If your 2nd gen is an Off Road Trim, this doesn't apply to you because you have ATRAC.

The earlier yellow wire mod involved clipping a black and yellow wire which "tricked" the 4WD system in 4LO to being in 4HI, but does not signal the transmission computer to use the 4LO gear shifting patterns when in 4LO and caused a blinking 4LO light signifying an issue.

The version 2 of the mod: cutting or removing wire #9 wire (darker yellow with black tracer) from PC labeled wire cluster on the schematic and connecting it to a 12v source because under normal conditions the ECU emits that 12v signal so you are just simulating that. (I'm assuming this #9 wire is responsible for cutting 12v signal to traction control system preventing the toggle of the TRAC system in 4LO). This "tricks" or "corrects" the traction control ECU rather than the 4WD system thus retaining the correct shift patterns in 4LO. This allows the VSC button to toggle betweem TRAC, TRAC OFF, and TRAC OFF and VSC off (factory mode) while in 4LO.

Side note: For this mod, do NOT cut the yellow and black wire from the original version yellow wire mod. Leave that alone. If you have cut it, it needs to be reconnected.

From what I have read from other member's doing this mod is the 12v source is the thick yellow wire shown in the photo below labeled 3. A 100 ohm resistor added between the 9-PC wire and the 12v source to maintain a low current. I have also read you can run a separate 12v source from the battery via add a fuse which will achieve a cleaner result.

Anyway, if I've missed something here, please correct me if I'm wrong. I hope this helps and maybe clears up the updated mod. I encourage you to read through the earlier thread below along with the yota tech write up to come to your own conclusions as well.

Original thread can be found here:
https://www.tacomaworld.com/threads/4low-trac.51946/

Another more detailed write up can be found here:
https://www.yotatech.com/forums/f117/4l-trac-done-right-280412/

A video showing how the VSC button operates after mod:
https://m.youtube.com/watch?v=noJDvLLayKY

Videos showing desired result here:
https://youtu.be/liBYXljAMcQ

https://youtu.be/G0AH1yIUp0A

https://youtu.be/TQxLeBbqZ5k













I completed this mod on my own truck, I ran the spliced wire through the center consol above the pedals and through the firewall to an add a fuse directly to the fuse box. Took me about an hour to run the wire and zip tie everything in place. I clipped the PC9 wire and used a double clip wire splice to connect the PC9 to my newly supplied red wiring that leads to the fuse box Photos below.

 

I'm just waiting for someone to make a male and female plug with the correct wires about 3" in length. This way I wouldn't have to butcher/molest my factory harness.

 

You have a 2017, your truck is already equipped with TRAC in 4LO right?

 

Yes but my wife drives a 2013...it has ATRAC and a rear locker. I've considered the mod for her because her biggest complaint more like only complaint is how touchy the anti-lock brakes are on the snow slick roads. I think with the mod it also disables the anti-lock brakes.

 

Ah ok, I do believe there is a separate ABS mod you can do too.

 

if shes driving a 2013 trd or 4x4 there is a one wire mod to disable all traction aids. if shes constantly hitting abs in the snow she really needs to slow down.... not going to create any better situation with ABS off.

 

the 2nd gen ABS sucks and is more likely to cause a crash than prevent one

the ABS is shitty, sensitive, kicks in early, and doesn't actually do anything; it just has a long siezure spasm that accomplishes nothing, wasting precious time and distance of not actually stopping the car.
Time that could've been spent actually stopping the car manually, if ABS was not there messing things up.

I've pulled an ABS fuse or two in the past in snow, to experiment/compare, and I was able to brake better manually on my own and with more feel/control.
ABS seems like something pretty hard to mess up, especially if the components are sourced from the same manufacturers.
Every other ABS vehicle I've had (different brands) performed well and not this poorly.
I'm not sure why/how Toyota managed to fuck up something so important from a safety standpoint

the warning will blink and buzz while not helping like it's just trolling

 

I used to hate the ABS on my Tacoma.

Tires and fast driving are often in play with this symptom. Let's assume it's a tire issue. Having a dedicated set of winter tires helps. Tires wear less in winter, so having 2 sets can help. Tire pressure can be at play also. Let 3 - 5 pounds out of each tire and see if she notices an improvement.

I run the same style/ type of tire both summer and winter. I get 2-3 good winters out of a set, then they become my summer tires. I get another 2-3 summers. This depends on how much driving I do and what tires I've chosen at that point. I've been doing this for more than 15 years with great results in driving performance from the tires.

Full disclosure:
I've had a faulty ABS sensor for almost 5 years now, so I haven't had ABS or TRAC in that time. I just let out air when I need more traction - or buy new tires. I'm a big fan of the Dean Backcountry MT3 these days. I get 3 winters and summers out of them, including 2K+ miles each spring and fall (4K+ total) just from road trips. I commute 50 miles per day to work also.

 

always been on decent tires aired correctly
Good (winter) tires are about having traction.
ABS is about what the vehicle does when it loses it. It's supposed to release brake force, then quickly re-apply it, many times in pulses, "faster than a human can"
even though there has been testing done where if somebody knows what they are doing, they can outperform the system
which is why performance cars often come with the option to disable ESP and ABS
the Tacoma ABS just handles loss of traction poorly

Not everyone is airing down for the couple hours there is snow
the ABS also kicks in too early when it's not needed
A/T's claim to last up to 50k miles when rotated

anyone can force ABS to kick on by braking too hard in a slick condition from a high enough speed,
which you normally avoid
while another vehicle ABS system may function well when engaged in that situation, the Tacoma's does not
I wonder who programmed the map that controls how the ABS behaves
it is probably not as good as whoever is making them for German cars, which are used in Germany, rest of Europe, Sweden, Finland; places known for people knowing how to drive/expecting their cars to perform well and know how to judge it, as well as snow

 

Im curious, what truck do you have (do you have a vacuum assist master cylinder or electric boosted one?)


Driving up to mammoth a few weeks ago in some nasty icy non plowed roads i slowly moved over a lane to let someone pass, up and over an ice mound in the center, i am 100% certain that traction/stability control saved my ass when the back end of the truck got stuck on the downhill side of the ice then quickly shot up over it.

 

not sure I'll have to look under the hood
'08 so whichever version is simpler with less parts/smaller and older
am guessing vacuum and not electric

 

08, unless you have the optional VSC package for that year its probably vacuum boosted with the separate ABS module. Its likely this reason for your distaste of the ABS system. The 09+ TRD OR 4x4's have a singular electric hydro boosted master cylinder / 4 channel abs unit all in one that does a much better job.

 

no VSC and no traction control, not many buttons to the left of the steering wheel just Clutch Start Cancel and controlling the bed power outlet, TRD Sport w/ LSD
makes sense
passenger cars with better performing systems are likely electronic and not vacuum

 

In the first picture, they splice into the 12v, wire from splice goes to resistor that is under black shrink wrap, and then resistor goes to the yellow/black wire from pin 9? Has anyone tried it without the resistor? Is it necessary or just a safer option?
I have been wanting to do this mod on my 2013 trd sport and just want to be crystal clear on what is known to work for others!

 

At least one person I've seen on here has done it without. It's a safer option. But with it being such a cheap little part and easy to do, why not?

 

I'm planning on running an add a fuse to the battery via separate wire to that wire. This is the 100% safe bet.

 

But I also don't have TRAC at all (base), so this mod doesn't apply to me, right? I do need a traction solution, bummed if this is the case..

 

My truck is base and has TRAC (2015). I was under the impression all 2nd Gen trucks had TRAC.

 

Here's a link explaining the different modes. Does your truck have a VSC or "squiggly tires" button?

https://www.tacomaworld.com/threads/a-trac-trac-auto-lsd-explained-easy-to-understand-i-hope.70551/

 

No buttons, 2007 base 4x4. Do have LSD but no buttons to control it (mechanical diff vs electrical?)