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-   -   A-Trac? (http://www.tacomaworld.com/forum/2nd-gen-tacomas/29902-trac.html)

JTech 03-11-2009 09:54 AM

So i have a 2009 Tacoma Doublecab off-road 4x4 with all the bells and whistles. I have figured out what almost everything does on it, mostly through trial and error, but the A-Trac. Can anyone tell me what it does, and when I can use it?

JDCPA 03-11-2009 10:31 AM

It's the electronic traction control.

fishshooter 03-11-2009 10:35 AM

A-Trac can only be used in 4Lo, it detects which wheels have the least traction and it uses the brakes on those wheels to try to trasfer the force to the other wheels.
Here it is on an FJ Cruiser:

TacoCo 03-11-2009 10:40 AM


Originally Posted by JDCPA (Post 458259)
It's the electronic traction control.

That would be TRAC, A-TRAC is for use in 4-Lo as posted above by Fishshooter. It's definitely confusing. Here's my understanding: TRAC is the electronic traction control that we have standard on the '09s that is available all the time in 2WD. It applies the brakes to the rear wheels to gain traction if slipping. A-TRAC applies the brakes to all 4 wheels in 4-Lo to gain traction if slipping.

JDCPA 03-11-2009 10:42 AM


Originally Posted by TacoCo (Post 458272)
That would be TRAC, A-TRAC is for use in 4-Lo as posted above by Fishshooter.

Hence A-TRAC, too, is an electroniclly based traction control.

LonghornTaco 03-11-2009 11:12 AM

Is this anything like a feeble limited slip diff in the front?

fishshooter 03-11-2009 01:28 PM

Do you think it would have done it without the A Trac on?
It's no front locker, but it seems to do good in the sand the few times I've played with it. There are some other u tube videos of it in the snow, seems to do well there too, but we don't get any snow here. You can turn it off if you don't like it. I don't think you can get the OR package (on the 4X4) without it coming with it.

JTech 03-11-2009 02:04 PM

Well thanks for the info next time I am out i will have to play with it. I am not gonna lie I am used to off roading with out any of these fancy things. The last taco only had a locking rear diff and i did just fine in it. I really don't use any of the traction stuff unless I am just playing with it. But hey it came with the truck so I figured i should at least know what it all does, and the owners manual is useless.

bmkshort 03-13-2009 08:00 PM

TRAC and A-TRAC are the same thing except that when A-TRAC is engaged, the ECU does not control engine throttle as it does in regular TRAC. The A-TRAC is like the AUTO-LSD is in 2wd mode but is for 4wd-lo only. Important notes to keep in mind....

All the different traction control features are similar except as noted.

2WD MODE -TRAC and VSC are always on (unless switched off, which kicks in the AUTO-LSD). TRAC controls wheel spin by applying brake pressure to the spinning wheel AND engine throttle output. VSC kicks in when it senses yaw rate loss in cornering skid situations.

4WD high- TRAC and VSC are also always on (unless switched off) EXCEPT TRAC only controls braking and NOT engine throttle output.
Similar to AUTO-LSD in 2wd but with VSC ready to function as needed.

4WD low- TRAC and VSC are automatically off. The A-TRAC switch is there to assist traction by using TRAC to appy brake pressure to the slipping wheel and/or wheels WITHOUT using engine throttle output. Similar to TRAC in 4wd-high except VSC is off.

Where did I learn this information you may ask? Well, let me say that after numerous phone calls to Toyota's customer service,various dealer service depts. and internet searching, I was basically forced to pay Toyota $10 to access their tech info site and download 39 pages in PDF format explaining in detail how their traction control system works. Why they like to keep this so secret is beyond me. They won't allow me to release this info to the open public but if anyone wants a copy, I will be glad to e-mail it to you. My e-mail address is .....bmkshort@cox.net :goingcrazy:

bmkshort 03-14-2009 03:37 AM

Forgot to mention that the PDF file I have starts on page 14 through 52. It was under their "new features section" and that was all that pertained to the traction control features.

Isthatahemi 05-13-2009 07:17 PM


Originally Posted by Krookz (Post 458437)
Well that looks really usefull :rolleyes:

I hope I can get a new Taco w/o that crap, when the time comes.

That statement doesn't make any sense. That FJ wouldn't have made it half way up without ATRAC. It was an almost perfect locker, front and rear. If anything the driver was way too shy.....
Do you know what the term neo-luddite means?

fasn8dave 05-13-2009 07:50 PM

I have an FJ with A-TRAC and actually used it while wheeling this weekend. You can feel the brakes vibrating - it's the ABS. The damn thing looked like a Tonka Toy crawling over rocks and a few downed trees... I was in one situation where I would have been "crossed up" but A-TRAC kept lurching me forward. It's kinda weird because you feel your vehicle braking while you're moving forward.

Years ago, if I had "right rear spin" happening on a 2WD truck, I'd stomp the brakes while gunning it and I'd usually get out (haven't tried that on my taco) - It's the same principal. The power is going to go through the path of least resistance. If you grab and slow down the wheel that's spinning, more power will be diverted to the other wheel.

I'd recommend it.

TL697 05-13-2009 08:22 PM

I use mine all the time here in the Colorado mountains... It works great...

fishshooter 05-14-2009 01:51 PM


Originally Posted by Isthatahemi (Post 602147)
That statement doesn't make any sense. That FJ wouldn't have made it half way up without ATRAC. It was an almost perfect locker, front and rear. If anything the driver was way too shy.....
Do you know what the term neo-luddite means?

I do, and I think you are correct in using it. :)

Silver Seeker 11-05-2011 08:17 AM

I have a 2010 Tacoma Sport. It was sold to me as having an "auto limited slip diff". I have read the posts in this forum many times since the dealer doesnt know anything about the truck.

I have the LSD off and RSC off switches, but no ATRAC switch. Does this only come on the off-road models? Can it be added to the sport model?

I have had previous trucks with real limited slip differentials and it is very disappointing having a much more expensive vehicle with open diffs.

Please advise
Silver Seeker

DueNorth 11-05-2011 08:22 AM

Atrac only comes in the TRD offroad models, not the sports. I suppose you could add it in yourself, but it would be to much of a PITA to do so. IMO, the LSD works pretty good here in Ontario during the winter, etc but if want even more traction, get lockers. (for off road use)

MonkeyProof 11-05-2011 08:23 AM

paging DavidK, paging DavidK,

Please report to the front desk!

HomerTaco 11-05-2011 08:23 AM

zombie thread revival again... :rolleyes:

DueNorth 11-05-2011 08:32 AM

Just noticed the thread dates, damn that is quite the thread revival. Way to much atrac talk lately. If you got a TRD Sport, stop worrying about atrac and lock it up already! Arb air lockers ftw...

David K 11-05-2011 10:43 AM

This is one of the threads I first came to after getting my third Tacoma in Dec. 2009. The statements above about the owner's manual being useless (as well as the salesmen) is right on, and that is why I read, tested, then posted so much on this.

For newbies, to clear up an otherwise excellent post by bmkshort in 2009:
TRAC in 4WD HI and AUTO LSD in 2WD both use brakes without any engine regulation.
TRAC in 2WD uses both brakes and engine regulation.

Toyota's use of the name 'TRAC' for two different sets of operations is confusing.

A-TRAC (Active TRACtion control) is a whole different 'animal' above what TRAC in H4 does... That is why ISTHATAHEMI and others (and me since) have called it being closer to 'lockers' on the front and rear than 'limited slip'.

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