ATRAC in 4LO only, not 4HI?

[chaz]

i know its been brought up over the years & debated so i thought id start this thread so that hopefully enough senior members will chime in & we all may finally find the correct answer to is ATRAC always active in 4wd or only on in 4LO.( not referring to the 4th gen trail edtion or 5th gen.) this is from my 06 v8 manual, " the active traction control system automaticly helps prevent the spinning of 4 wheels when the vehicle is started or accelerated on slippery road surfaces. when the ignition key is turned to on the system automaticlly turns on. theres more but it states nothing about being active in 4LO only. heres a post by bulldog at 120 that seems to agree with this, ATRAC vs CENTER DIFF LOCKER - Toyota 120 Platforms Forum i know that THAI also has some posts on atrac. so here it is to end the debate, will any & everyone with information please post to help eliminate cluttering/debating of other members post on subjects different than atrac. im sure myself & others would like to know the correct answer so as not to give out bad info to new members. :thanks:

 

[rebelbowtie]

Well if ATRAC doesn't work in 4Hi my truck has problems because it works in 4Hi...or at least what I think is ATRAC working. Makes weird popping and clicking noises

 

[JB.]

Bulldog's post says it well.

It's a nomenclature thing as the usage of the term ATRAC has changed over time. In the 4th gen (I guess minus the TE) the brakes are always active in controlling wheel spin in response to lost traction. This gets more aggressive in low range. That's about it.

 

[rebelbowtie]

So what's different about the ATRAC in the 4th gen TE?

 

[Synister]

The 4th gen TE has a dedicated ATRAC switch which only works in 4LO. This version of ATRAC is extremely aggressive and seems to engage at a far lower rate of slip. I wheeled a couple months ago with Tacoma and there was significantly more wheel spin before his braking system engaged to regain traction.

 

[mrpanic7]

i know its been brought up over the years & debated so i thought id start this thread so that hopefully enough senior members will chime in & we all may finally find the correct answer to is ATRAC always active in 4wd or only on in 4LO.( not referring to the 4th gen trail edtion or 5th gen.) this is from my 06 v8 manual, " the active traction control system automaticly helps prevent the spinning of 4 wheels when the vehicle is started or accelerated on slippery road surfaces. when the ignition key is turned to on the system automaticlly turns on. theres more but it states nothing about being active in 4LO only. heres a post by bulldog at 120 that seems to agree with this, ATRAC vs CENTER DIFF LOCKER - Toyota 120 Platforms Forum i know that THAI also has some posts on atrac. so here it is to end the debate, will any & everyone with information please post to help eliminate cluttering/debating of other members post on subjects different than atrac. im sure myself & others would like to know the correct answer so as not to give out bad info to new members. :thanks:

I know you made this thread because of the guys on that other discussion, so i'm going to copy and paste my same response to contribute :

Here the facts.

-ATRAC is ALWAYS on and can only be disabled when the "Zero Point" is erased.

-ATRAC works in 4HI and 4LO. NOT just 4Lo. I know I use it all the time including this past weekend. (This video I made demonstrating ATRAC, was taken in 4HI A-TRAC Demonstration - YouTube)

-Not sure about the 4th Gen Trail Edition, but there is NO switch for ATRAC like there is in the FJ for example.

-I have done ZERO research on the 5TH GEN, so it may indeed be different than what I said above. BUT everything I said is correct regarding 4TH GEN's.

 

[chaz]

yes, & thanks to all.

 

[Synister]

Here the facts.

-ATRAC is ALWAYS on and can only be disabled when the "Zero Point" is erased.

-ATRAC works in 4HI and 4LO. NOT just 4Lo. I know I use it all the time including this past weekend. (This video I made demonstrating ATRAC, was taken in 4HI A-TRAC Demonstration - YouTube)

Both not true.

From my 09 TE manual Ch 2-4 Pg. 182 "Active Traction Control System(L4 mode of 4WD models)"

"System operation"
"Vehicles without the A-TRAC switch Stop the vehicle, shift the shift lever to N and turn the four-wheel
drive control switch to the L4 position. Then the system will auto- matically activate.
Vehicles with the A-TRAC switch
l When activating the system with the center differential lock unlocked
Stop the vehicle, shift the shift lever to N and turn the four-wheel drive control switch to the L4 position. Then the system will auto- matically activate.
l When activating the system with the center differential lock locked
Stop the vehicle, shift the shift lever to N and turn the four- wheel drive control switch to the L4 position. Then press the center differential lock switch.
Press the A-TRAC switch to activate the system.
At this time, the active traction control indicator will come on.
To cancel the system, push the switch again."

 

[JB.]

That's an example of the changing terminology.

In the '03-'07 4runner manuals (can't say about '08) the acronym "A-TRAC" doesn't appear. The term that does appear "Active Traction Control" makes no distinction between high and low range in those manuals. I guess based on that you could say that A-TRAC didn't appear in the 4th gen until '09. The manuals, however, are not the only Toyota publication.

How the brakes act to control wheel spin is pretty simple. It's the inconsistent terminology that's difficult.

 

[mrpanic7]

Both not true.

From my 09 TE manual Ch 2-4 Pg. 182 "Active Traction Control System(L4 mode of 4WD models)"

"System operation"
"Vehicles without the A-TRAC switch Stop the vehicle, shift the shift lever to N and turn the four-wheel
drive control switch to the L4 position. Then the system will auto- matically activate.
Vehicles with the A-TRAC switch
l When activating the system with the center differential lock unlocked
Stop the vehicle, shift the shift lever to N and turn the four-wheel drive control switch to the L4 position. Then the system will auto- matically activate.
l When activating the system with the center differential lock locked
Stop the vehicle, shift the shift lever to N and turn the four- wheel drive control switch to the L4 position. Then press the center differential lock switch.
Press the A-TRAC switch to activate the system.
At this time, the active traction control indicator will come on.
To cancel the system, push the switch again."

Dude, did you miss the point about idk about the TRAIL EDITION. You have a Trail Edition. You have a ATRAC switch....non-Trail Editions don't.

If you read over what I said the 4th Gen's (Not sure about the Trail Editions)
there is NO ATRAC switch, and ATRAC does operate in 4HI. I was outside using it all day yesterday, w/o the center diff locked even.

Next time you want to claim some's statements "not true" read the entire post first. You simply cannot say any of what I said isn't true, because my ATRAC gets a workout a lot. In 4HI, not just 4Lo.

Here's the manual: http://www.panavi.kz/toyota/4runner/215/owners_manual/t4r_owners_manual_04.pdf

ATRAC starts at pg. 170, nothing about only works in "4 Lo"

This thread also has some great info: http://www.toyota-4runner.org/general-discussions/12-01-up-4wd-system-trac-vsc-torsen-t-3-a.html

--If I sound rude or offensive, I do apologize, that is not my intention, just to provide accurate information for everyone.

 

[JB.]

It sounds like, starting with the 09 TE, the term A-TRAC is now used for the more aggressive mode that works only in low range and requires the push of a button.

The problem with this is that the lone term "traction control" has always included the ability to use either/both brake pulsing and engine suppression. In present time, there seems to be no term that describes the type of "active traction control" which is always active, doesn't involve engine suppression, and works in hi or low. In other words, the other 4th gen years when in low range or in hi range with the center diff locked.

Synister, I presume the last two sentences above describe how your truck acts when the A-TRAC button is out of the picture. Is this correct?

 

[BlackWorksInc]

You guys are right. Its mostly a terminology issue rather than an actual program difference. (Though programming may have been adjusted/upgraded along the years). What they're trying to get accross more is that as you need more and more control of the vehicle (i.e. slipping in gravel/mud/slush) and you need to get into lower and lower gears, eventually locking up the center differential, they adjust the parameters of the programming to help you out.

The Traction Control functions the same as "A-TRAC" the difference is in programming and slight differences in mechanism actuation of the system.

 

[Synister]

Interesting discussion. My manual is not a TE specific manual, its for a 09 4runner and it does address some of the unique features to that model year (i.e. the atrac switch on TE's). Your manual is an 04 manual and it addresses some unique features to that year. Ill get to the differences in a minute. ll repost what came from my manual, just pretend I don't own a TE, just an 09. Ill even remove the bits about the atrac switch and highlight for you why its relevant to the original post. After, I'll add some more stuff from the manual (just an regular ole 09 T4R) that can further clear the issue.

To recap:
From my 09 manual Ch 2-4 Pg. 182 "Active Traction Control System (L4 mode of 4WD models)"(note; not called A-TRAC yet and pertains to any 4wd model)

"System operation"
"Vehicles without the A-TRAC switch Stop the vehicle, shift the shift lever to N and turn the four-wheel
drive control switch to the L4 position. Then the system will automatically activate."

Now, the reason why discussions are great is because it highlights a very important difference between early 4th gens and later models, namely the ability to turn off additional traction features by long-pressing the VSC/TRAC button (the "gray wire mod" for you early 4th gen owners). Maybe Toyota had to separate ATRAC from TRAC in the computer to make this work right, I dunno. But I read your manual and for your truck, you are right, ATRAC is a 2/4HI/LO feature. On later years, ATRAC is 4LO only, as per the definitions (not found in your manual).

Ch. 2-4 pg 188 of my regualar ole 09 manual.

TRAC (Traction Control)
Maintains drive power and prevents the rear wheels (2WD models and H2 mode on Multi-mode 4WD models) or all wheels (4WD models except on L4 mode) from spinning when starting the vehicle or accelerating on slippery roads.

A-TRAC (ActiveTractionControl) for L4 mode on 4WD models
Maintains drive power and prevents the all wheels from spinning when starting the vehicle or accelerating on slippery roads.

So, to answer the OP, per the manual, ATRAC is indeed a 4LO only feature...at least on 09, maybe 08+? For 03-07 it does look like ATRAC is available in 2WD or any 4WD. Why Toyota differentiated between 4HI and LO starting late in the model years is curios. After all, the definition says they do very similar things, except maybe the algorithms for the ABS are a bit more aggressive for the slower wheel speeds found in 4LO, hence a more "active" traction system. And, for the very confusing ATRAC switch, an even more aggressive option for a Trail Edition vehicle. The real questions are what years did the change to 4LO occur and what are the performance differences, if any? KCCO...

 

[mrpanic7]

Interesting discussion. My manual is not a TE specific manual, its for a 09 4runner and it does address some of the unique features to that model year (i.e. the atrac switch on TE's). Your manual is an 04 manual and it addresses some unique features to that year. Ill get to the differences in a minute. ll repost what came from my manual, just pretend I don't own a TE, just an 09. Ill even remove the bits about the atrac switch and highlight for you why its relevant to the original post. After, I'll add some more stuff from the manual (just an regular ole 09 T4R) that can further clear the issue.

To recap:
From my 09 manual Ch 2-4 Pg. 182 "Active Traction Control System (L4 mode of 4WD models)"(note; not called A-TRAC yet and pertains to any 4wd model)

"System operation"
"Vehicles without the A-TRAC switch Stop the vehicle, shift the shift lever to N and turn the four-wheel
drive control switch to the L4 position. Then the system will automatically activate."

Now, the reason why discussions are great is because it highlights a very important difference between early 4th gens and later models, namely the ability to turn off additional traction features by long-pressing the VSC/TRAC button (the "gray wire mod" for you early 4th gen owners). Maybe Toyota had to separate ATRAC from TRAC in the computer to make this work right, I dunno. But I read your manual and for your truck, you are right, ATRAC is a 2/4HI/LO feature. On later years, ATRAC is 4LO only, as per the definitions (not found in your manual).

Ch. 2-4 pg 188 of my regualar ole 09 manual.

TRAC (Traction Control)
Maintains drive power and prevents the rear wheels (2WD models and H2 mode on Multi-mode 4WD models) or all wheels (4WD models except on L4 mode) from spinning when starting the vehicle or accelerating on slippery roads.

A-TRAC (ActiveTractionControl) for L4 mode on 4WD models
Maintains drive power and prevents the all wheels from spinning when starting the vehicle or accelerating on slippery roads.

So, to answer the OP, per the manual, ATRAC is indeed a 4LO only feature...at least on 09, maybe 08+? For 03-07 it does look like ATRAC is available in 2WD or any 4WD. Why Toyota differentiated between 4HI and LO starting late in the model years is curios. After all, the definition says they do very similar things, except maybe the algorithms for the ABS are a bit more aggressive for the slower wheel speeds found in 4LO, hence a more "active" traction system. And, for the very confusing ATRAC switch, an even more aggressive option for a Trail Edition vehicle. The real questions are what years did the change to 4LO occur and what are the performance differences, if any? KCCO...

It seems it may just be the 09's that are so different, according to the manual...

So what it sounds like to me, is for an 09, Traction control is basically our VSC? Does your manual mention anything about VSC? That's what your manual is making it sound like, cutting power when the vehicle is losing traction, and the ATRAC being itself, but only a 4Lo feature ( in the 09)

As for 03-08/07 (?), ATRAC is active in 4HI and Lo, except our "Traction Control" as labeled in the 09, is really our VSC.

I even read some things talking about ATRAC kicking in when in 2WD, which I can test this weekend.

So does your manual mention VSC? If not I'm thinking 09 Traction Control = VSC, but like you said, slight differences with ABS, brakes, etc.

--NOTE: Got a hold of a 2009 4Runner brochure, and it does mention VSC, so now I'm a little more lost comparing them, however it does make me want an 09 more http://www.toyota120.com/GenDocs/20094RunnerBrochure.pdf

---ALSO.... Brochure on the 09 drivetrain/diffs/traction etc setup http://www.toyota120.com/GenDocs/4RunnerTEtraction.pdf

 

[mrpanic7]

So according to both pdf's I posted above ^^, Here is the detailed info from the 09 brochure:

Traction Control: TRAC helps prevent the drive wheels from slipping if the driver
presses the accelerator pedal excessively when starting off or
accelerating on a slippery surface. <--This being the same in all of them it is what cuts our power--correct?

ATRAC: The A-TRAC operates when the A-TRAC switch is turned on with the
drive mode in L4L.
A-TRAC controls the brake hydraulic pressure that is applied to the
slipping wheel, and distributes the drive force that would have been lost
through the slippage to the remaining wheels in order to achieve an
LSD effect.<---So it seems you were correct Synister, it would appear that the ATRAC system would be more aggressive, and for the 09 year only being used in L4.

VSC: The VSC helps prevent the vehicle from slipping sideways as a result
a of strong front wheel skid or strong rear wheel skid during cornering.<--Same

Seems we are closer to the facts....

 

[Synister]

Jackpot below!! Hands down best explanation ever, 33 pages to whet your whistle, although the first few are the meat and potatoes. Only difference I can see is the 4runners added ability to either lock or unlock the center diff. The Taco's are always locked. For the 08-09 owners out there who want more clarification about additional VSC off modes, the link below is also very helpful. To summarize, the difference between A-TRAC ( 09 with the switch) and Active Traction Control (a mode available on all year T4R's in both HI and LO ranges) is A-TRAC uses a hydraulically boosted brake actuator for super strong braking and the other uses vacuum suction to boost brakes for more gradual but still effective pseudo LSD. By all means, the first page of posts below is a gem.

A-TRAC / TRAC EXPLAINED

 

[chaz]

this has turned into a good read. so let me get this right, "active traction control" as per the 03-07 or 08 manual, does mean or is referred to as ATRAC, so we can call it that, correct? also, in the pre 09 years it works in 2wd, 4hi & 4lo, BUT in 09+ toyota changed the way it worked slightly, offically changed the name to ATRAC, & made it available in 4LO only, correct? so when discussing ATRAC in general on this forum or anywhere else, we have/need to specify which years being talked about when referring to how/when it works, correct?

 

[mrpanic7]

this has turned into a good read. so let me get this right, "active traction control" as per the 03-07 or 08 manual, does mean or is referred to as ATRAC, so we can call it that, correct? also, in the pre 09 years it works in 2wd, 4hi & 4lo, BUT in 09+ toyota changed the way it worked slightly, offically changed the name to ATRAC, & made it available in 4LO only, correct? so when discussing ATRAC in general on this forum or anywhere else, we have/need to specify which years being talked about when referring to how/when it works, correct?

a good read indeed, but a couple things I want to clarify on what you said:

-ATRAC is named the same for all the years, not just 09.

-The major difference is that in 09 (and those models Taco/FJ) that have the switch, ATRAC is more aggressive in L4, but still functions in H4 and 2, just not as aggressive.

 

[mrpanic7]

Jackpot below!! Hands down best explanation ever, 33 pages to whet your whistle, although the first few are the meat and potatoes. Only difference I can see is the 4runners added ability to either lock or unlock the center diff. The Taco's are always locked. For the 08-09 owners out there who want more clarification about additional VSC off modes, the link below is also very helpful. To summarize, the difference between A-TRAC ( 09 with the switch) and Active Traction Control (a mode available on all year T4R's in both HI and LO ranges) is A-TRAC uses a hydraulically boosted brake actuator for super strong braking and the other uses vacuum suction to boost brakes for more gradual but still effective pseudo LSD. By all means, the first page of posts below is a gem.

A-TRAC / TRAC EXPLAINED

Awesome write up indeed! Great find! I'm going to put all of our information to the test this weekend and test ATRAC in all modes, and try and video it up as best I can so we can review.

I think it would be a good idea to sit down and do a really clean, simple, and factual write up of ATRAC/TRAC, along with some video action.

Since everyone contributed, I think what I posted below sums up our teamwork ...

 

[JB.]

With the breadth of information out there, perhaps a basic view of 4th gen 4wd would be useful.

Forgetting the VSC yaw sensing (for simplicity), the response to low, traction is pretty basic. The brakes pulse to control wheel spin. Sometimes this can involve engine suppression. Two things, that's it. The basic operation is more straight forward than the naming. So, for nearly all 4th gens in 4wd, traction is handled thusly:

Hi, center unlocked---brakes active=yes--throttle suppression=yes
Hi, center locked------brakes active=yes--throttle suppression=no
Lo, center unlocked--brakes active=yes--throttle suppression=no
Lo, center locked-----brakes active=yes--throttle suppression=no

The manual is incomplete in addressing engine suppression for low range, unlocked. Having used the mode extensively, I've never experienced engine suppression, nor have I heard about any. It's been widely reported that atrac is more aggressive (not dramatically) in low range than in high and that agrees with my usage but it's not anything official.

Anyway, terms that have been used by people for a long time to describe the traction management in the 4 modes above are as follows. (A-TRAC does not appear in the 03-07 manuals, though. Probably '08 too. The term used there is the full phrase Active Traction Control)

TRAC or VSC
A-TRAC
A-TRAC
A-TRAC

Some of the reading linked here seems to call into question whether the acronym A-TRAC should have ever been applied to the pre-09 4th gens. That would mean that A-TRAC is not an acronym for Active Traction Control. Considering how early the acronym appeared and how widely it has been used in describing the 4th gen, that would be surprising, if true. I'm skeptical that Toyota has been completely consistent with the terms for over a decade now across models, generations, and various departmental publications Many will remember the amount of Toyota misinformation about features in the early stages of the 5th gen rollout. In any event, that's why I like descriptions of the operations, sans labels. Much easier to stay out of trouble that way.

I guess I'd have to own a newer model to care enough to put the effort into learning all the traction modes and their names. It's still just brake application (with added levels of aggressiveness) with or without engine management. I realize catchy names aren't going away anytime soon, but the mode descriptions could easily be captured by something like, say, BTC 1, 2, 3 or 1+, 2+, 3+ (brake traction control with numbers denoting levels of aggressiveness and plus sign denoting engine management ON).

It will be interesting to see what continues to come out of this thread.