[ah64id]

TRAC, A-TRAC, VSC, Auto LSD ?'S

Okay, so I picked up my 07 the other day and have some questions from the experts on TRAC, A-TRAC, VSC, and Auto LSD....

So accoring to the 05-06 repair manual the truck has A-TRAC, TRAC, VSC, DAC, HAC, and Auto LSD. From what I can tell TRAC works in 2wd only, A-TRAC in 4wd. VSC in 2WD, and Auto LSD when VSC is off. I know about DAC and HAC.

So when I press the VSC off switch the AUTO LSD and slip indicators come on. When I go into 4WD I get the VSC OFF light (different from slip idicator that comes on with VSC OFF switch). According to the owners manual the VSC OFF switch turns off traction control in 2wd with a breif push. Then you hold it for 3 or more seconds and VSC and Auto LSD turn off.

VSC only works above 9mph. I cannot find a bottom end speed associated with TRAC or A-TRAC.

So when you turn off TRAC your turning AUTO LSD on. So what is the difference between TRAC and Auto LSD? Does TRAC limit engine power and BFD, and Auto LSD only use BFD?

Is the A-TRAC on the taco the same as the FJ? (descriptions sound the same)

So from what I can tell you can choose in 2wd, TRAC, Auto LSD, VSC/TRAC, or good ol nothing.... In 4wd you can choose A-TRAC or nothing... Am I reading this all correctly?

Does anyone have a link to the 07 repair manual, as it has a VSC off swtich now?



EDIT: When reading this thread for information I suggest you disregard what K20Z3Si has to say, he has no clue what he is talking about.

 

[bigbadyoda]

What taco u get sport or offroad... Cause I just got mine and Don't know wtf button your talking about lol..... Mines a manual though lol

 

[Janster]

Oh my gawd....I thought I researched things pretty good cuz I'm looking at getting an 07. But everything you've just said is giving me a headache (of confusion)!!

Here's something I found:

Anti-lock brakes with electronic brake-force distribution (EBD) is standard as is brake assist. The former balances brake force at each wheel while the latter increases brake force during panic stops. Vehicle Stability Control w/ Traction Control (VSC+TRAC) is available on all except X-Runner. This system detects front- and rear-wheel slide while cornering and assists the driver regain control with either throttle intervention or braking individual wheels. VSC uses an automatic limited-slip differential, which uses brake intervention instead of an internal mechanical device to reduce tire slippage. VSC+TRAC includes Hill-start Assist Control (HAC) that controls the brakes to prevent the Tacoma from rolling backward or slipping sideways while climbing from a stopped position on an upgrade. When ordered on a 4x4 V6 with the TRD Off-Road Package, Downhill Assist Control (DAC) is included. This system uses engine braking and independent control each wheel brake to regulate downhill speed.

Hmm.....I'm curious to know... that when you get an 07 TRD Sport package with an Limited Slip differential - is that a mechanical LSD (inside the diff) or the 'AUTO LSD' (uses the brakes)??? I was under the impression it was a mechanical LSD.
Hmmm..... perhaps a phone call to the dealership is in order.

 

[ah64id]

Its an OffRoad, its the button circled.. thats not my truck I have an auto, but that one is a 6spd...

 

[ah64id]

Oh my gawd....I thought I researched things pretty good cuz I'm looking at getting an 07. But everything you've just said is giving me a headache (of confusion)!!

I thought I understood it too, until now I am probally thinking about it too much...

Hmm.....I'm curious to know... that when you get an 07 TRD Sport package with an Limited Slip differential - is that a mechanical LSD (inside the diff) or the 'AUTO LSD' (uses the brakes)??? I was under the impression it was a mechanical LSD.

AFIK its a mechanical one....

 

[justinh]

Oh my gawd....I thought I researched things pretty good cuz I'm looking at getting an 07. But everything you've just said is giving me a headache (of confusion)!!

Here's something I found:


Hmm.....I'm curious to know... that when you get an 07 TRD Sport package with an Limited Slip differential - is that a mechanical LSD (inside the diff) or the 'AUTO LSD' (uses the brakes)??? I was under the impression it was a mechanical LSD.
Hmmm..... perhaps a phone call to the dealership is in order.

It is manual, it is the same one that was previously available in Tundras.

 

[itsmeagain5789]

ok,those three slots are completely empty on mine. i got the trd offroad 4x4 DC auto. from what iheard, i think they only have VSC in some states, not all.

 

[Slergio]

I'm curious to know... that when you get an 07 TRD Sport package with an Limited Slip differential - is that a mechanical LSD (inside the diff) or the 'AUTO LSD' (uses the brakes)??? I was under the impression it was a mechanical LSD.

I'd like to know as well. Anybody?

 

[tacosupreme]

So when you turn off TRAC your turning AUTO LSD on. So what is the difference between TRAC and Auto LSD? Does TRAC limit engine power and BFD, and Auto LSD only use BFD?

Is the A-TRAC on the taco the same as the FJ? (descriptions sound the same)

So from what I can tell you can choose in 2wd, TRAC, Auto LSD, VSC/TRAC, or good ol nothing.... In 4wd you can choose A-TRAC or nothing... Am I reading this all correctly?

Does anyone have a link to the 07 repair manual, as it has a VSC off swtich now?

Dude you are reading way too much into Toyota's marketing hype. It's all the same system. Simply put, a wheel slips and the brakes get applied. There are 5 different acronyms describing this wonderous function, and one switch to disable it. A-Trac is just Trac on the front axle. Trac gets turned off automaticly when the locker is engaged on models so equiped, and VSC doesn't come on untill 9 miles an hour so you aren't locking up a wheel backing out of your driveway. I did a mod to disable all that crap and ABS, because it's no fun. I still use it on wet autobahn or when the wife is driving, but that's about it. The only thing different to the 07 manual would be one pin added to the 4WD ECU for the VSC switch, wich is on connector F-12 if you feel like poking around behind the glove compartment.

 

[ah64id]

Dude you are reading way too much into Toyota's marketing hype. It's all the same system. Simply put, a wheel slips and the brakes get applied. There are 5 different acronyms describing this wonderous function, and one switch to disable it. A-Trac is just Trac on the front axle. Trac gets turned off automaticly when the locker is engaged on models so equiped, and VSC doesn't come on untill 9 miles an hour so you aren't locking up a wheel backing out of your driveway. I did a mod to disable all that crap and ABS, because it's no fun. I still use it on wet autobahn or when the wife is driving, but that's about it. The only thing different to the 07 manual would be one pin added to the 4WD ECU for the VSC switch, wich is on connector F-12 if you feel like poking around behind the glove compartment.

Thats kinda what I thought, but the repair manual and owners manual refer to them as different systems. The main thing I am confused on is the difference in Auto LSD and Trac, as in 2wd I can select one or the other. And also turn VSC off, so there have to be some differences, otherwise why be able to select independant systems?

 

[Janster]

It is manual, it is the same one that was previously available in Tundras.

Good to know! That's what I wanted....
I won't have all the other stuff (VSC, H...D...). My husband has all that on his Acura and it's all too confusing. Just give me a transfer case with 4hi/lo and plain old ABS without all the extra stuff. More sensors and stuff to go faulty.

 

[K20Z3Si]

If you have an off road you dont have an LSD. You dont have TRAC or A-TRAC only VSC is an option.

http://www.toyota.com/vehicles/minisite/fjbulletin/index.html?section=1.2.1

A trac is like a locker. for the front, its an OPTION on the FJ-Cruiser only and the FJ comes standard with the TRAC system and VSC. The Tacoma is all Mechanical

 

[ah64id]

If you have an off road you dont have an LSD. You dont have TRAC or A-TRAC only VSC is an option.

http://www.toyota.com/vehicles/minisite/fjbulletin/index.html?section=1.2.1

A trac is like a locker. for the front, its an OPTION on the FJ-Cruiser only and the FJ comes standard with the TRAC system and VSC. The Tacoma is all Mechanical

Sorry, but some of that info is inaccuarte. You are correct in the offroad does not have a mechanical LSD, but mine has and Auto LSD. According to my window sticker I have TRAC. According to the repair manaul I have A-Trac as well. I have a switch, as previously stated that allows me to turn off TRAC, or VSC, or both. Please re-read the info above, its correct.. .your info is wrong. I am simply asking the differences in AUTO LSD and TRAC, as both are 2wd features and I am pretty sure I can select betweem the two. As well as turn them and VSC off.

And on the FJ A-TRAC is for the front AND rear. With the locker engauged, TRD FJ's and post NOV production FJ's it only works the front, but with the rear locker disengaguged it works front and rear.

 

[K20Z3Si]

And where is this magical LSD? You can only have a locker or a LSD not both. A Auto LSD means its going to engage automaticly when it slips.

Traction control is not cool for off roading, its a sheeple safty feature

Normally Traction Control and VSC are combined. It turns off in 4WD or somthing. The manual can explain it. With the locker on you have no electric driving aids, because it would make the locker useless the whole point of the locker is to have both wheels spining. You can get a LSD with out the sport package and it comes standard with the sport, the only ways to get it.

 

[ah64id]

And where is this magical LSD? You can only have a locker or a LSD not both. A Auto LSD means its going to engage automaticly when it slips.

Traction control is not cool for off roading, its a sheeple safty feature

Normally Traction Control and VSC are combined. It turns off in 4WD or somthing. The manual can explain it. With the locker on you have no electric driving aids, because it would make the locker useless the whole point of the locker is to have both wheels spining. You can get a LSD with out the sport package and it comes standard with the sport, the only ways to get it.

Again, your wrong. Auto LSD is a Brake driven LSD, not a mechanical LSD. And Auto LSD means that the brakes are used to control wheel slippage. LSD's dont have on off switches, unless they are driven by an ECU and are not mechanical. If you can turn it on and off, like in the 07's, it cant be mechanical.

Your telling me to read the manual, like your an expert. I have read the manual and am asking the questions I have on here.. for people who know what I amd they are talking about. And since you gave me a link to a toyota page I would assume you have looked around there, so you must have seen where it talks about the different LSD's, mech and auto.

Do a little looking aroung, I know what mech LSD's are.. i HATE them.. I know what a locker is and how to use it. Check out the 92 in my sig. Done a little wheeling in my day. Just trying to figure out all the features of the new ECU driven 4wd system.

TRAC works great in AWD in my 4runner, and i think it has the ability to work as well in the A-TRAC mode in my taco when in 4WD. I do like that I can disable it and still use wheelspin for the occasion when I need it. With the begining of my family my wheeling habbits are changing. A-TRAC will be great with 4 chains in deep snow, and if it inhibits me I just turn it off and keep on truckin.

I still want to know the difference between Auto LSD and TRAC. Both are 2wd functions that I can control independently of VSC. I know VSC is for skids, and will limit throttle. I am going to guess that Auto LSD and TRAC dont limit throttle with the application of brakes. Or maybe TRAC also montiers front wheel speed in 2wd for assistance and Auto LSD only moniters the rear chanels... Would be nice to know.

And since you brought up electronic aids and the locker, A-TRAC works in conjuction with the locker on TRD FJ's and post-NOV production FJ's. In essence the A-TRAC works as a auto BFD locker up front with the mech locker out back.. really slick... would love this in my taco.

And you can too have an LSD and a locker, just not in a toyota axle..

 

[K20Z3Si]

I have none of those options then, how much did all of that cost?

 

[Mmtoy]

And where is this magical LSD? You can only have a locker or a LSD not both. A Auto LSD means its going to engage automaticly when it slips.

Traction control is not cool for off roading, its a sheeple safty feature

Normally Traction Control and VSC are combined. It turns off in 4WD or somthing. The manual can explain it. With the locker on you have no electric driving aids, because it would make the locker useless the whole point of the locker is to have both wheels spining. You can get a LSD with out the sport package and it comes standard with the sport, the only ways to get it.

You're perpetuating some pretty strong myths here.

On the tacos:

1) VSC (vehicle stability control) is a method used to reposition the center of gravity of the vehicle when the computer detects a dangerous situation. It uses selective braking and engine control to do so. This is turned off when 4-wheel is engaged or speed is low.

2) TRAC (Traction control) is a method of decreasing wheel spin on sudden acceleration by braking ALL powered wheels and/or by decreasing engine RPMs.

3) Auto LSD is a method of transferring torque to the wheel that can best use it, by braking the slipping wheel. This IS different from traction control, as it only applies to a single wheel and does not operate in 4-wheel drive mode. Auto LSD only brakes the wheel that's spinning, while traction control brakes all wheels.

 

[KANEMAN23]

I don't care for those features and I've got them all on my 03' 4Runner. I'm probably in the minority but I don't like the VSC, TRAC, HAC, DAC either.

I don't like the way everything lights up, beeps, brakes the wheel(s), and takes away the ability to throttle. I want to be in control of my vehicle and not the other way around. Give me a manual 4wd selector lever and the rear locker. An option for a front one would be nice too.

I still love my 4Runner but I like my 99' more for it's simplicity.

 

[ah64id]

I don't care for those features and I've got them all on my 03' 4Runner. I'm probably in the minority but I don't like the VSC, TRAC, HAC, DAC either.

I don't like the way everything lights up, beeps, brakes the wheel(s), and takes away the ability to throttle. I want to be in control of my vehicle and not the other way around. Give me a manual 4wd selector lever and the rear locker. An option for a front one would be nice too.

I still love my 4Runner but I like my 99' more for it's simplicity.

I love the systems in my 03 4Runner. I have only really used them on compact snow as its the wifes rig, but wow what a great system.

Mmtoy: Thanks for the info. I hadnt thought of it that way, thou it makes perfect sence.

It was an $850 option in the JBL TRD Offroad package.. if it works like my 03 I will love it and think its worth it. Its one of the reasons I got the JBL Package.

 

[Mmtoy]

I love the systems in my 03 4Runner. I have only really used them on compact snow as its the wifes rig, but wow what a great system.

Mmtoy: Thanks for the info. I hadnt thought of it that way, thou it makes perfect sence.

It was an $850 option in the JBL TRD Offroad package.. if it works like my 03 I will love it and think its worth it. Its one of the reasons I got the JBL Package.

I love these systems too. In fact, it took me two years (of on-and-off looking) to find a taco with them and also with 4x4...And I HOPE it'll be wasted cash for all of these systems, including the side curtain airbags.

The reason I love them? Because, nearly all situations that they're going to become active are situations where I've already lost some amount of control of the vehicle.

Perfect made-up example: You're towing a full load in the rain and the person in front of you (too close, you tail-gater), driving a corolla, suddenly brakes. What can you do to avoid destroying their vehicle?

1) You can brake, but the fact is that your 11000 pound vehicle (truck+load+trailer=max capacity of 11000 pounds) isn't going to stop before the corolla stops. ABS is designed to provide you with steering control under hard braking conditions (if your wheels are locked, you have little/no steering), but it won't shorten your braking distance. Unless you steer away from the car, you are going to hit it.

2) You can swerve. If you swerve poorly, you'll likely jackknife and smash the corolla anyway. As soon as you turn the wheel, your braking distance is lengthened. The harder you turn, the less traction your wheels have, so the less braking power and less control they give you. So if you swerve incorrectly, you're not only going to hit the corolla, you're going to hit it at a higher speed (and the energy of the collision is proportional to velocity squared). You'll also likely roll your truck because now your center of gravity is all screwed up. You were better off just braking.

3) If you have computer controlled stability control (and the ABS it relies on), you can brake AND swerve, and you can do it safely (well, more safely). As you're turning into the other lane, your computer will recognize that the center of gravity and rotational vector of the truck is not right and will selectively brake certain wheels, depending on which ones need to be put back into place. ABS won't allow your VSC to lock those wheels, so you'll still have steering control. You will be able to successfully avoid plowing through the corolla.

Now, imagine that your wife is the one driving the corolla and the truck behind her has been tailgating for far too long when she looks away from scowling into the rear view mirror just in time to see the deer and brake/swerve (also utilizing her own VSC).

Do you really want to trust your family's lives to some yahoo's driving abilities? I'd prefer to trust a computer and the physics behind it... The same people building these systems are building the spacecraft that go to Mars, they're the same people building the rockets that launch your GPS satellites into space, they're the same people building the GPS systems. I've got tons more faith in their understanding of physics than I do in my (or any random Joe's) driving ability.

I'd say a 30% reduction in head-on collisions in Japan is proof enough...

http://www.google.com/search?q=vehicle+stability+control
http://money.cnn.com/2003/09/25/pf/autos/what_is_esc/index.htm
http://www.consumeraffairs.com/news04/stability_control2.html

Of course:
Once we go offroad? I'm not going fast enough to matter, so I'm happy as a clam that they're turned off as soon as I engage my transfer case.

Wow, that's way too long a post...Sorry.