2nd Gen, No TRAC in 4L?

I have done the research and I know about the yellow wire mod. I have not found a good explanation as to why Toyota set it up so that non TRD Off Road, are lacking TRAC in 4L.

Does anybody have a solid answer?

I want to do the mod, but it just seems strange that Toyota arranged things this way, there must be some drawback?

Thanks

--I have got a 2011 4x4 DC AT SB V6 SR5

 

They probably want to sell more TRD models.

 

(At a Tacoma design meeting, sometime in the late 2000s)

Engineer 1: I've finished the design of this new Traction Control system to control wheelslip by applying the brake to the spinning wheel. It works great.

Engineer 2: Cool! How's it work when offroading in 4 lo?

Engineer 1: Works well. But sometimes if you're using it a lot, after a while the brakes get hot.

Legal: What? Brakes get too hot? We can't have that!

Engineer 1: Well, no matter what if you use brakes a lot, they eventually overheat. It's just physics. But I could design an enhanced system that won't overheat as quickly. But it's more expensive.

Finance: Must keep costs down!!

Marketing: Wait a minute. We're always looking for more options to up-sell consumers to our higher-margin TRD packages. Tell me more about this enhanced system.

Engineer 1: Well, it would work exactly the same, it would just have a more powerful master cylinder with better brake fluid cooling.

Marketing: We can work with that. Sort of an "Advanced Traction Control."
I know! We'll call it A-TRAC!

And so, the plan was formed. Finance was happy. Legal was happy. Engineering was happy. Marketing was very happy. And they all lived happily ever after.

 

I was thinking along the lines that you guys are. It is frustrating to think they would essentially reduce the capability that is "natural" to the truck.

Also, I would think 99.9% of consumers would not be educated enough to figure out all those details and let it influence thier purchase.

 

To the third post, which came in while I was writing my reply, my truck has a factopry warning system for overheating brakes. To some extent, that problem is addressed. The story does make sense though.

A side question: I am under the impression that TRAC only deals with the rear axle and ATRAC deals with both, is that correct?

 

Well that is pretty cool, I thought I only had rear axle control! So are we just going to conclude it is a $$ issue within toyota, or a hot brake issue?

If it is a hot brake issue, you could just splice a switch into the yellow wire, as some have done, and only activate 4L TRAC at the most demanding times.

 

TRD offroad doesn't get Trac in 4Lo either. Makes sense since we have the a-trac option instead. I've never tried hitting the auto lsd in 4Lo ut im assuming it doesn't do anything. I don't think you would have as much an issue with overheating as trac uses less aggressive braking than a-trac...

Maybe toyota just left it out because it was easier. They didn't have it set up to work in 4Lo because A-trac was available on some trucks for those who want it and want to pay....

Bottom line... Toyota did it to make money or save money

 

research before buying is usually a good decision....

Also, if toyota included every option they would only have 1 trim of the tacoma...

they make different trims at different prices for people that research what they need in a truck

 

I did a lot of research before i bought, so thanks for backing me up.

It is not really the case that an option was not added, it would be more accurate to say they proactively disabled an option. The brakes are there, the sensors are there, the computer is there, everything is already there to have TRAC in 4L. They added a wire to take away a capability, as far as I can tell anyway.

 

I'm sensing a DavidK appearance soon.

 

well technically that wire sends a signal that you are in 4lo. by cutting the wire the truck doesnt realize its in 4lo and leaves trac on as if its in 4hi but the tcase does in fact go to 4lo. The beauty is that it only works when you have different wheel speeds so its rare to overheat the brakes. Ive never done it, mud, snow rocks sand, it works great. I dont know why toyota doesnt already have trac in 4lo but bjmoose's explaination is awesome

Also keep in mind that it takes pretty good amount of throttle for it to be effective. Also, unlike an open/open truck, because the trac uses the brakes to put a load on the wheel it prevents cv failure from spinning freely... so pin it to win it and youll make it out of most situations...

 

I wonder if that is for a reason though... like would you not want TRAC or ATRAC if you were using 4L in vehicle recovery?

 

ive pulled out my fair share of vehicles with trac in 4lo. It helps alot!

 

You forgot " The End "

Great story Bullwinkle

 

Just trying to play devils advocate to figure out why they would want to disable it in 4L... seems to make no sense.

 

Before 2009, there was no A-TRAC on the Off Road Tacoma... only the rear locker... and the added traction does help a great deal. So, the truck in 2008 or earlier was still awesome. But, you would still buy the Off Road for added traction. If you got a Sport or SR-5/ base then you didn't want the added traction of a rear locker so why cry about no trac in L4...?

With the Off Road, you still have the rear locker, and in 2009 + models, you have A-TRAC in L4.

TRAC in H4 works the same as AUTO LSD in H2 in that there is no engine regulation, just brake action... ie. a stronger limited slip.

TRAC in H2 has both engine regulation and brake action. Push the traction (VSC OFF) button in H2 and you go into AUTO LSD (no engine regulation).

Put the truck into H4, and TRAC is on without any regulation. You have an effective limited slip system that reduces spinning of loose tires so traction tires can continue to work for you.

You don't want any traction help in H2 or H4? Stop the truck, push the VSC button and HOLD it down for 3-5 seconds. TRAC shuts off, and you can spin around with open differentials!

Put the truck into L4, and you can wheel with open differentials, or you can lock the rear differential, or for the most traction you can activate A-TRAC... which is TRAC on steroids... matches wheel rotation across the axles as front or rear lockers do. However, it does periodically release the locking so you can steer without difficulty and will automatically lock up any tire that begins to spin faster than the others, so engine power isn't directed to a free spinning tire and away from a traction tire, the way open differentials do. Call A-TRAC "Automatic lockers" perhaps?

I have wheeled in A-TRAC for hours on trails and it never has automatically shut off from over-heating... That is a something you don't need to worry about. You have a rear locker as back up if you need it.

A-TRAC or REAR LOCKER information doesn't help if you don't have an OFF ROAD TRD TACOMA from 2009+.

The rest of you be glad that Toyota put TRAC on ALL Tacomas so at least you can do the 4 Lo Trac Mod and have limited slip in L4!


Choices Choices Choices... Thank you Toyota!

 

Good prediction!

Do you think I need to put this in my signature again?:

4WD OFF ROAD TACOMAS HAVE 9 DRIVE MODES:

1) 2WD: VSC and TRAC active, engine regulated ('Limited Slip Lite').

2) 2WD: 'AUTO LSD' ('TRAC OFF MODE'). No engine regulation for 'strong' limited slip.

3) 2WD: 'VSC OFF MODE' (TRAC is off for 'open differential').

4) 4WD-Hi: VSC and TRAC active. No engine regulation for 'strong' limited slip.

5) 4WD-Hi: 'VSC OFF MODE' (TRAC is off for 'open differentials').

6) 4WD-Lo: VSC and TRAC are both off in L4 ('open differentials').

7) 4WD-Lo: 'A-TRAC' on gives a 'locker-like, super strong' limited slip, front and rear.

8) 4WD-Lo: Rear Differential Locked and open front differential (A-TRAC off).

9) 4WD-Lo: RR DIFF LOCK + A-TRAC on, 3 MPH limit.