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

Again, I think you are missing my question. A-TRAC DOES NOT normally work in 4LO unless you have YWM correct?

So Normally is no YWM there is no A-TRAC in 4LO correct?
So if I don't have the YWM in my truck, trying the e-brake in 4LO will do nothing but slow me down correct?

 

So does the Yellow wire mod enable VSC and A-TRAC?
A-TRAC being it slows the wheel spinning and the engine output?
or does it only do the wheel spinning adn A-TRAC is off.(engine output)?

 

The YWM has nothing to do with A-TRAC, A-TRAC is it's own separate thing and only available if you have an Off-Road.

Without the YWM in 4lo you have open diffs, with the YWM it allows your truck to use limited slip in 4lo instead of just 4hi.

https://www.tacomaworld.com/threads/4low-trac.51946/ Read this thread, has pretty much everything you need to know about the YWM and what it does.

Using the e-brake with or without the YWM can help send power to the wheel that has traction at the cost of wearing out your e-brake.

 

What Cold_Toad said...

A-TRAC is its own animal, it requires the hydraulic brake booster. All Tacomas (EXCEPT the Off Road TRD 4x4) have a vacuum break booster.

TRAC is a limited slip system. A-TRAC is a no slip system that is more closely matched with front and rear locking differentials.

The Yellow Wire (4-Lo Trac) Mod allows TRAC to work in L4, not A-TRAC.

TRAC (limited slip) is not as mighty as A-TRAC (no slip) but is better than no TRAC (all slip)!

 

Exactly... and Toyota used some poor name choices which does not help.

Here are the levels of traction, in my opinion, from least to most. Only the Off Road TRD has a locking rear differential and only the 4WD Off Road TRD has A-TRAC (and MTS/Crawl in 3rd generation):

1) 2WD VSC OFF = No traction control (stop, press and hold in VSC button 3+ seconds).
2) 2WD TRAC = Limited slip through braking and engine regulation to reduce tire spin. [Standard Mode]
3) 2WD AUTO LSD = 2WD limited slip through braking of non-traction tire (quick press of VSC button).
4) 2WD Rear Locker = 2WD Off Road TRD only. Both rear tires get 50/50 power split, even if one has no traction.
5) 4WD-HI, VSC OFF = No traction control (stop, press and hold in VSC button 3+ seconds).
6) 4WD LOW RANGE = No Traction Control. [Standard Mode]
7) 4WD-HI, TRAC = Limited slip through braking and engine regulation to reduce tire spin [2009-2011 had no engine regulation].
8) 4WD-HI, TRAC OFF = Limited slip through braking of non-traction tire (quick press of VSC button). [2012+]
9) 4WD LOW RANGE + Rear Locker
10) 4WD LOW RANGE + A-TRAC
11) 4WD LOW RANGE + A-TRAC & Rear Locker

 

Yes! 2016+ automatic trans 4x4 Off Roads have MTS (Multi Terrain/ Multi-level A-TRAC) instead of one level A-TRAC.

 

Not at all.

My 2010 has no engine regulation in H4. They added the regulation in 2012 with a button push to get the traction control without regulation, called TRAC OFF.

In preventing wheel spin, by controlling the throttle (backing off the gas) you reduce the spin caused by too aggressive driving.

 

Question for y'all.
I'm driving in town a lot and have been messing with the LSD on/off (2WD Auto LSD, 2017 Gen 3) using the VSC switch. I find that my truck drives a lot smoother (it's not rough riding or anything) but overall feels better when it's on. Does it matter if I'm making my daily trips with it on?

 

The manual doesn't recommend it (fear of overheating the brakes) but in reality, if you are on dry pavement there will be no excessive braking for traction. I can't image why AUTO LSD mode changes how smooth the truck drives, weird?

 

Thank you. I appreciate it.
I know. Its weird. I can't explain it. Might mess around with it more this week.

 

In AUTO LSD, the VSC is turned off under 30 mph... but if a dangerous swerve occurs, it will come on automatically.

 

Hey,

Not sure if this the best thread to post this on or not. Please direct me to the best place if it's not.

I am currently not a Tacoma owner, but in the market for one. I live on a mountain on the outskirts of Seattle (average grade of the road is 10-15%). This past winter we had several weeks with snow on the ground and a few days where I felt trapped with my infant in the house. Not a feeling I want to repeat. Looking to get a 4x4 truck to do the occasional towing (household work and maybe a boat or popup in future), some off roading in future, and help me get up and down the mountain in the snow. Pretty sure a Tacoma fits the bill. Currently looking at used models (2010-2015) as a new one isn't finically feasible right now.

I am having trouble figuring out what options I need to help with the above situations. I've been doing a fair amount of reading on here and other places and still feel lost. Any help or advice that you are willing to give is greatly appreciated. Thanks!

Must haves:
Crew cab (gotta put the carseat somewhere)
Tow Package
TRD Suspension (I think)

On the fence:
ATrac
Locking Rear Diff
Bed Size

 

The Off Road TRD 4WD has both A-TRAC and the locker. No other model does. They give the truck the most STOCK traction. Get a 4 door, because the baby grows but the truck doesn't! Only bed on the 4 door Off Road 4WD 2nd Gen. is 5 ft. Lots of room.

 

First of all, thank you for this awesome write-up. I come back to it over and over again.

Just a little vent on some things ive been going through. maybe some insight can be given here. I was unable to find any in the "3rd gen mt" thread.

I have a 16 OR/MT and I drive on the beach 90% of the time i use any of these features. I drop air pressure to 25psi and have no trouble getting getting to and from areas. Occasionally, i have issues getting movement from a dead stop in some of the softer patches. I'm not stuck and I don't need to rock back and forth. The issue is that I just can't get the tires to start going. I need considerable gas and the power does not transfer to the tires. the engine or the brakes just prevents the tires from turning. the more gas i give it, the harder the entire car shudders and shakes with NO tire movement, and I'm off the clutch (as weird as that sounds) - All of this is performed in

• 4) 4WD-Hi: VSC and TRAC active. No engine regulation for 'strong' limited slip. - *note: this may no longer be true.
  According to the manual: If the vehicle gets stuck in fresh snow or mud, TRAC/VSC/Trailer
  Sway Control systems may reduce power from the engine to the
  wheels. You may need to turn the system off to enable you to rock the
  vehicle in order to free it.
• Now a 4b) 4WD-Hi: TRAC off (pressing VSC button once while in 4WD-Hi only turns TRAC off light on)
• 5) 4WD-Hi: 'VSC OFF MODE' (TRAC is off for 'open differentials'). - *note: once in 4HI and in stopped position, press and hold VSC for 3+ seconds and 'VSC' light (car with swervy tracks) and TRAC OFF light will turn on.

I have not yet tried #5. I thought that the #4b was the #5 and didnt think anything of it until recently. I will report once ive done so. Any input would be most welcome.

 

Hi Spiderpig, and thank you for the kind words!

Over the past 7 1/2 + years since getting my current Tacoma, discovering and explaining how this fantastic system called A-TRAC (and now MTS/Crawl) works has been a quest of sorts.

This thread really applies to the 2009-2011 models. In 2012, TRAC OFF in H4 was added as a selectable choice rather than being the only choice (and better choice, of course). The 2012 models are in TRAC with engine regulation and a quick press of the VSC button gives you TRAC OFF (which is a terrible name because it is MORE TRAC because the engine regulation is turned off).

I have made a 2012-2015 version of this explanation but this original one is what gets refreshed most.
Now, we have third Gen Tacomas with A-TRAC only on the manual transmission trucks and an adjustable A-TRAC in the automatics, now called Multi-Terrain-Select (MTS) and a foot-free drive control called Crawl (like DAC on my truck for downhill creeping and no chance of sideways sliding).

I sure would appreciate someone with a 2016+ Off Road 4x4 to do what I did for their truck or invite me to go on a run with them out to Ocotillo Wells or another area to see how the new stuff all works!

So, to respond to your concerns, #4 is for 2009-2011 and 4b is for 2012+ (as you guessed)! GOOD JOB!

#5 (VCS OFF) is useless as far as I am concerned as it makes the system dead or allows one tire per axle to spin and the other to do nothing (open differentials). The ONLY benefit, as Toyota tells, is that allows your tires to SPIN FREELY to spin out mud or snow if they that bad of shape!

As the wording is confusing, remember in H2 and 2012+ H4:
TRAC is light Traction Control; TRAC OFF is MORE Traction Control; VSC OFF is NO Traction Control.
L4 has no traction control unless A-TRAC (MTS) is on or the rear is locked

 

That is a TERRIBLE name then. . that actually explains a lot. Thanks for the clarification!

I really appreciate the insight. I realize im out of the band of what you are describing, but since this thread is the most useful information I had no choice but to seek your help here. Thanks David K.

 

Oh, not at all... the band welcomes all!

Most on this traction confusion applies to all 4WDs and not just the Off Road TRDs. The many selections are mostly in 2WD and 4WD-HIGH, which all 4WD Tacomas have. The Low Range traction is only better with the Off Road TRDs because we have A-TRAC/MTS and the Locking Rear Differential. There isn't too much confusion on those selections in L4. The Sport and other Tacomas only have L4 and no stock trick traction help (we don't need to talk about the 4 LOW TRAC MOD now, do we?).

In H2 and H4 on ALL Tacomas is where the majority of confusion rests...

You have 3 choices in H2 and 3 in H4. This applies to 2012 and newer 4WD Tacomas. The 2009-2011 Tacomas in H4 are naturally and normally in what they call now TRAC OFF, only back then it was called TRAC (without regulation). H2's stronger traction control was and still is called AUTO LSD.
What I mean by "strong" is that there is no throttle cut or engine output regulation in AUTO LSD or TRAC OFF Modes... providing the maximum get moving and stop spinning action. A spinning tire does not move you but if that spinning tire is braked and the energy is transferred to the other tire, that is on solid footing, your truck has a better chance to move! This is why I favor TRAC OFF MODE to turning the system off which allows the tires spin freely. I NEVER use VSC OFF, never. I have never been stuck with my 2010 Tacoma, and I have tried!

H2:
Standard is TRAC ("Limited Slip Light")
Quick press of VSC button is AUTO LSD ("Limited Slip Strong")
Stop and hold in VSC button is VSC OFF ("No Limited Slip")
H4:
Standard is TRAC ("Limited Slip Light")
Quick press of VSC button is TRAC OFF ("Limited Slip Strong")
Stop and hold in VSC button is VSC OFF ("No limited slip")
L4:
Standard is VSC OFF ("No limited slip")
*Push A-TRAC button ("VERY STRONG Limited slip, nearly matches front and rear lockers")
*The Rear Locker is for emergency unstuck only, per Toyota. It can be used with or without A-TRAC on. A-TRAC with the locker on goes active under 3 MPH when (and only when) the rear is locked.

*On the Off Road TRD only

 

And the rearend goes out when used.

 

know what would make all of this simpler? if the lights on the instrument panel just said these things rather than saying "trac off".

 

I'm surprised there's not an app. for that......yet