A-TRAC/TRAC/AUTO LSD Explained (Easy to understand, I hope!)

I just can't understand why on earth Toyota didn't put these simple explanations on one of the hideous visor stickers in our trucks instead of all the CYA language. (Well, yes I can: lawyers, liability, bullshit, bullshit, blah blah blah...)

But it would be WAY better. Maybe one of our resident vinyl experts could make some cash with a coverup sticker for the visors...

 

Thank you. It has taken me years to refine and figure different ways to explain these functions so that your head doesn't explode! My interpretations of the various traction choices are my creation and not from Toyota or any mechanic... so, I will admit they may not be exactly accurate. However, as you found, they sure make using the choices SIMPLE (K.I.S.S.), yes?

Also, 2009-2011 4WD Tacomas do NOT have the selectable TRAC to TRAC OFF mode in H4. H4 is automatically in TRAC OFF (but it was called TRAC [without engine regulation] those years).

 

I read the first couple pages of this thread and find the information clear and understandable. Excellent well thought out. Thank you for all your time and effort. I have a question which is I’m sure already answered but I’m asking anyway. I have a 2009 TRD Sport 4x4. Are you saying that when I’m in 4H the limited slip is automatically working? Also does the limited slip in 4H work with just the rear wheels or with the the front also? I do not have A Trac.

 

2009-2011 Sport (and all other 4WD models):

Toyota's TRAC (limited slip) in H4 works on all 4 wheels.
In H4, the engine output regulation (throttle cut) is OFF. This is the stronger level of traction control. No button push needed. This is equivalent to AUTO LSD in H2 (also called TRAC OFF).

In 2012, they added a button push to turn the engine regulation off (TRAC OFF MODE) and made the standard mode TRAC with engine regulation, as it is in H2.

 

Thanks for the great explanation. I now perfectly understand. I think the the limited slip both front and rear when in 4H makes a huge difference. I’ve noticed over the years that I can get into places other 4x4’s can’t or have a difficult time including steep dirt and gravel roads and muddy roads. I think the limited slip makes a big difference over some other 4x4’s.

 

It does!
In my trials of the various choices back 8 years ago, when my truck was new, I discovered that H4 was MORE capable at climbing than L4 without the A-TRAC or locker on.

In other words, the low range with open differentials (standard mode) could not do better than high range with the traction control. Now, that is where the Off Road shines, because with A-TRAC (or even just the rear locker), low range then became a beast and the truck climbed like a Sherman Tank!

Those who did not have the Off Road 4WD model learned to perform the 4 LOW TRAC (Yellow Wire) MOD to trick the system into giving them TRACion control while in L4... Not as good as A-TRAC, but a whole lot better than the open differentials that 4-LOW operates with.

 

All good info. I’d just like to add that all 3rd gen Tacoma’s (non-off road) have TRAC available in 4lo. The Yellow wire mod is no longer necessary on 2016+ TRD sports, SR5 etc..

 

This is a big deal and the first I have read of it. How did you find this out and why no other mention on TW, I wonder? Please share the photos of the manual or lights that come on, etc.

 

I have long suspected this was the case but never found any reference on TW. I heard a Toyota Rep mention that all 3rd gen Tacomas have brake activated traction control in 4 wheel drive but there was no documentation about it. I set out yesterday to put my theory to rest in Hungry Valley OHV park in CA. I tried two attempts at a steep off camper hill where I knew I would lose traction on two corners. The first try was with everything off in 4 low. (VSC TRAC off, Held button down for 5+ sec). I didn't make it far before the right front and left rear lost traction. I could not go forward at all. I pressed the traction control button once and TRAC OFF disappeard from the dash. I gave it some gas and low and behold, the brakes kicked in and transferred power to the other tires and I made it up no problem. I should have gotten a video of it but I was by myself and was concentrating on driving.

I should add that this is not as effective as A-Trac or MTS/CRAWL but it is very helpful for those of us without the OFF ROAD package. I was debating getting a locker for My TRD SPORT but this discovery kinda lessens the need for it.

 

Yes that is correct, however all 2016+ Tacomas have TRAC available in 4 low, which was not the case for 2nd Gen trucks.

 

Question - if on a gen 2 you can get a form of Trac control in L4 by basically snipping a wire why doesn’t Toyota just manufacture them from the factory without the “yellow” wire. I can’t imagine anyone not wanting this. It would be a great selling point for the 4x4 people. I’m wondering if there is a down side to this or some mechanical problem that may be caused by long term use. Any thoughts on this?

 

Thats a great question for a Toyota powertrain engineer. I don't know why TRAC is disabled in 4low on second Gens. Its a great tool to have in case you get stuck. I'm glad they rectified it for the 3rd Ten trucks.

 

There is a desire to have no traction control as an option so you can make the tires spin (to clean out mud/snow, they say). 2009-2015 models can press and hold-in the button for VSC OFF (no traction control) in H2 and H4, and in L4 it is normally in VSC OFF.

So, if things changed in 2016, you go into L4 and do not see the VSC OFF light on (as we do with 2nd gens), but can activate it but pushing the VSC button and holding it is while stopped for 3+ seconds, eh? For us, the VSC button does nothing in L4.

 

You still see the VSC off light illuminated because VSC is disabled in 4low regardless of 2nd or 3rd gen. The difference is, TRAC is on by default on 3rd Gens. It can be disabled by holding the button down for 3+ seconds.

 

I've been reading this thread with great interest & trying hard to stay clammed up. Now everybody's got my wheels spinning. With my '13 SR5, what happens when I add a "real" locker like an ARB to the now "open" rear axle. How do the OEM functions integrate if at all? I'm wanting a true locking diff. (At least the rear) but with all the electronic this 'n that going on like the ABS, I'm wondering if I'm not getting into one big headache. Once all the laughing stops about how brain dead I am, could someone please spoon feed me an answer because my brain is getting full. Thanks!

 

Until I can drive one ride in one, I am not going to guess. That Jimmy says the VSC OFF light is on, (no matter what) in L4 is a bit odd. VSC OFF usually is the same as TRAC turned off (notice I didn't say 'TRAC OFF', as that is TRAC with engine regulation off, giving more TRAC).
The odd exception is H2 AUTO LSD where 'TRAC OFF' is ON but VSC is OFF to 30 mph, then comes on.

I would like to know what lights are on (or off) in L4, then L4 with a quick push of VSC button, and finally L4 with button held in 3+ seconds... all three choices at 0 mph, then each at 31+ MPH. THANKS!!

 

A quick push of the VSC button in 4 low does absolutely nothing on 3rd gens. In 4 Hi, it will give you TRAC OFF (mode) like we all know. The confusing part is, when you hold the button down in 4 low, TRAC OFF light appears. VSC and TRAC OFF. This does not mean the same thing as in 4 HI.

So heres the kicker. The TRAC OFF light means different things in 4 HI and 4 Low. (on 3rd gen Trucks) In 4 HI, like you correctly stated it means TRAC is on and Engine regulation off. IN 4 Low it actually means what it says....That TRAC and VSC are off completely.

Ill try and upload some pics later

 

Thanks... Toyota needs some help with naming things, indeed!

 

If only there were an lcd screen that could display any text when buttons are pressed to let you know what they are doing... And if only they could place this screen in the instrument panel.

 

I went back and read many of the 70+ pages of this thread. All good info.In fact really good information. Learned a lot. But for me what really matters is that I learned limited slip is automatically engaged in 4H both front and rear on my gen2 TRD 4x4. Unless you have lockers front and rear you just can’t get better than that. The e locker in 4L off road doesn’t help you in mud, snow or ice. The last thing I want to do is put it in 4L locker or not in mud , snow or ice. In 4L barely touch the gas in mud or snow and you will simply spin your wheels. The taco 4H with limited slip is just simply awesome.