A-TRAC vs. TRAC

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From FJCruiserForums.com:

Trac : Traction control. All FJ's have this, both 2WD & 4WD. Works automatically when ignition is started (no push button needed). Works by applying brakes and controls (decreases) engine throttle to give added traction to varying wheels when system detects wheel slippage/spinning ("think spinning your wheels on ice"). Works all the time in 2WD and in 2H & 4H (AT) or HL (MT). This system basically helps to maintain traction in slippery conditions such as wet/icy for forward movement by applying brakes and controlling engine throttle to regain/maintain traction as a safety feature.
TRAC is disabled in 4LO. Again, you don't want this system to control engine power when you are climbing obstacles.

ATRAC : More aggressive form of TRAC & for 4WD OFF ROAD use only. Does the same thing as TRAC except it doesn't cut/control engine throttle. Instead, it transfers torque from slipping/spinning wheel(s) to non slipping wheel. This gives added traction & forward momentum to overcome Off-road obstacles. This can only be engaged while in 4LO (AT) or LL (MT) and by pressing the "ATRAC" switch.
Also, only 4WD models with the Rear Diff Locker have ATRAC capability. Even then, you need the $50 ATRAC switch installed to use this system if you didn't purchase either Upgrade Pkgs with your FJ (UP or UR).
*AT: to go into 4Lo, stop, put into Nuetral, then shift into 4Lo (short knob).
MT: refer to manual, sorry I have the AT.

Auto LSD: found on 2WD models. Similar to ATRAC for 4WD. Must press the Auto LSD button/switch to activate it.

VSC (vehicle stability control) : integrates ABS, TRACtion control, engine control, etc to prevent the vehicle from skidding when cornering. Prevents oversteering or understeering & will save your ass if your car loses control (Thai). Detects angular momentum and tries to control direction of skid. VSC is automatically activated when the FJ reachs 9mph or 15km/h.
*VSC automatically turns itself off (VSC off light on dash comes on) when 4H/HL or 4Lo/LL is activated (AT/MT) or when the Rear Diff is locked. VSC is for preventing rollovers at high speeds thus not used while wheelin' in 4Lo/4H.


Rear Diff Locker : Not all 4WD models come with this. Switch/button activated. You must be in 4Lo or LL. It locks the rear axle so that it acts as one rod. If one wheel turns, so must the other so that not all power/torque is lost to the spinning wheel. Diff b/t Rear Locker and ATRAC is that with
Rear Diff Locker, both rear wheels spin in unison and steering tends to be rather difficult (so be careful near small ledges, ruts, drop offs). ATRAC, rear wheels are not locked and steering is not comprimised so you have more control of the vehicle. Apparently one works better than the other for certain situations while wheelin or you can do the Atrac-Locker Hack and have the best of Both worlds.

So at relatively high speeds TRAC will slow you down & aid in traction control in slippery situations, while VSC will give your more control during turns, skids, and saving your ass (roll over prevention).

While ATRAC and Rear Diff Locker is specifically for use in 4LO. While either of these are engaged, the TRAC and VSC is turned off. This makes sense, b/c they are safety systems to slow you down when you're going to fast, while ATRAC and RDL will aid to move you forward when you're going too slow or stuck.

Other Recommendations: Not necessary to be in 4H when it's raining or lightly snowing in the city, since this will deactivate VSC. VSC is what will save your ass at high speeds (per Thai). If you stay in 2H, you have TRAC and VSC to make necessary corrections if you slip & slide. If you do choose to put it in 4H for these situations, at least you still have TRAC working for you. But again, Thai says TRAC is turned off after 40+ mph or so. Many here feel you shouldn't be going fast (>40mph) while in 4H. 4H is probably more appropriate if you encounter thick/compacted snow or icey roads as FJJack mentions. You can quickly find out which is better with a test this winter. Try 2H and 4H and make up your own mind.

4H and 4L should generally be reserved for off roading use. 4H for light trails (gravel/dirt roads) and 4Lo for mod-large rutts/rocks. Obviously if a meteorite hits your town and all hell breaks loose then by all means put her in 4H/4Lo as needed.
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I did mine just like is shown in THIS thread or you can use...

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That description from the FJ Forum is not correct. Both systems are known as "Active TRAC" per Toyota. It's us wheelers that choose the term when we write, TRAC or ATRAC.

The systems are the same. Again, it is Active TRAC.

Their are a few differences between years and model Toyotas. The differences are:

*Wheel sensors (for accuracy)
*Software (different for each vehicle type...programmed to accomplish different agendas...In a LC or FJ it's for traction first and there's no throttle cut. In a Sequoia it's slow it down to a stop via throttle cut first and then traction control if possible)
 
Shotts, you need to do some more home work. At least for the FJ, there is Trac for high range and A-trac for low range. It may be different in the 100's. Have a good day. Robbie
 
powderpig said:
Shotts, you need to do some more home work. At least for the FJ, there is Trac for high range and A-trac for low range. It may be different in the 100's. Have a good day. Robbie
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On ALL Toy vehicles the "programming" or "flash" or "software" is different for each vehicle and differs as well in high or low range. On the Seq it even can cut throttle.

The "name" for the system is "Active TRAC" for all the models.
 
powderpig said:
Shotts, you need to do some more home work. At least for the FJ, there is Trac for high range and A-trac for low range. It may be different in the 100's. Have a good day. Robbie
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Oh, and I am aware Toyota markets the system a bit differently on the FJ because "Active Trac" is an "option".

On the FJ they make you "buy" the option pack in order to get the "A" part. In reality it's there in the CPU and we all know a free work around wiring-wise. In the 100 you just get both standard so there's no marketing/option/name confusion.
 
For the Fj, Trac is for high range only and will cut power and brake a tire(if senses wheel spin). if needed to make you go forward. In low range A-trac uses no cutting of throttle, but will brake the wheels if it senses wheel spin.
I agree that they market it differently for different models, but also to the extent of how sensitive the computer programing is.
So you say on the Sequia A-trac will cut power in low range or just in High range with 4 wheel engaged(most Sequias are multi mode systems)? I think you are confusing the Landcruiser model with the rest of them. I will look into this more, Hopefully you will too. Robbie
 
powderpig said:
For the Fj, Trac is for high range only and will cut power and brake a tire(if senses wheel spin). if needed to make you go forward. In low range A-trac uses no cutting of throttle, but will brake the wheels if it senses wheel spin.
I agree that they market it differently for different models, but also to the extent of how sensitive the computer programing is.
So you say on the Sequia A-trac will cut power in low range or just in High range with 4 wheel engaged(most Sequias are multi mode systems)? I think you are confusing the Landcruiser model with the rest of them. I will look into this more, Hopefully you will too. Robbie
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Regardless of how the system works on each vehicle, my statement was to point out that the system Toyota uses is called Active TRAC. Other makers use the system as well. How and when they kick in varies though the traction control system is the Active TRAC system.

*In the FJC...VSC (which is standard) cuts throttle in High, not the traction control system. Traction control activates the brakes.
*In low, VSC is disabled so no throttle is cut. Traction control is there and ready to go IF you have the option or do the mod. This is where marketing confuses the issue by having a A and non-A on the FJC.

Regarding the Seq? I don't know for sure how the software works. I do remember reading:
**Traction control was slow to kick in. More wheelspin than most.
**Soon as you hit the sand they said the traction control kicked in and the thing cut throttle which ended up with the stuck vehicle, and ASAP. I would GUESS that they were in 4-LO if in the sand and if so the Seq is different for some reason (big, more intrusive for safety, etc). IF they were in 4-Hi then the Seq isn't different because I'd bet it was VSC that kicked in, in testing and not traction control.

Nothing "system-wise" on the FJC is unique. Like other Toy SUV's it has VSC and Traction Control, Active-TRAC brand traction control.
What differs? Software and the fact that Toyota locks out the intervention in 4-LO so they can sell you an option package. Smart for them.
 
In high range in the FJC, TRAC will cut power on the engine as well as use brakes to have the vechicle move forward(in slippery situations, like snow and ice). VSC will also cut power when it senses a loss of stability or a bad corner turn(as well as a few other problems).
I do agree in low range one layer of VSC is turn off, with no loss of power to the engine in all situations.

Terms, Do you actually see Active TRAC in your manual? Or do you see Active traction control in your manual and you are imposing your word on Toyota's manual. I was looking in our 07 4/runner's book for terms. On the dash is TRAC, in the Book it is described as Active Traction Control, not Active TRAC.
The only place TRAC is showen is on the dash lights.
In low range on all (modern electronic) toyota trucks/suv's, VSC will not work to control the throttle, it will be some programing in the TRAC system. This was also a problem in some of the earlier 4/runner stuff as well. But not in the L/C stuff(if I remember correctly).
I believe that A-TRAC was coined for the FJ as a real reactive Trac system that was not found in other Toyota lines. Even in the L/C it was not as reactive. This was due to the type of ABS system that is found in the newer FJC and 4/Runners with the embedded magnetics in the wheel hub(which is not in the 100 series, so it will not react as fast using hall effect sensors instead). The newer hub sensor is more sensitive(and acurate) to wheel movement, thus wheel differentiation.
Again Shotts, due your home work, you are confusing the systems. And the models, there are differences in the different trucks. I will look at the new 200 series (and tundra) to see if the magentic hub sensor abs system is employed. This will then give the vechicle in question the ability to have more acurate info on wheel speed differential.
Look in your manual and see if the term you are using Active TRAC is in it. later Robbie
 
powderpig said:
In high range in the FJC, TRAC will cut power on the engine as well as use brakes to have the vechicle move forward(in slippery situations, like snow and ice). VSC will also cut power when it senses a loss of stability or a bad corner turn(as well as a few other problems).
I do agree in low range one layer of VSC is turn off, with no loss of power to the engine in all situations.

Terms, Do you actually see Active TRAC in your manual? Or do you see Active traction control in your manual and you are imposing your word on Toyota's manual. I was looking in our 07 4/runner's book for terms. On the dash is TRAC, in the Book it is described as Active Traction Control, not Active TRAC.
The only place TRAC is showen is on the dash lights.
In low range on all (modern electronic) toyota trucks/suv's, VSC will not work to control the throttle, it will be some programing in the TRAC system. This was also a problem in some of the earlier 4/runner stuff as well. But not in the L/C stuff(if I remember correctly).
I believe that A-TRAC was coined for the FJ as a real reactive Trac system that was not found in other Toyota lines. Even in the L/C it was not as reactive. This was due to the type of ABS system that is found in the newer FJC and 4/Runners with the embedded magnetics in the wheel hub(which is not in the 100 series, so it will not react as fast using hall effect sensors instead). The newer hub sensor is more sensitive(and acurate) to wheel movement, thus wheel differentiation.
Again Shotts, due your home work, you are confusing the systems. And the models, there are differences in the different trucks. I will look at the new 200 series (and tundra) to see if the magentic hub sensor abs system is employed. This will then give the vechicle in question the ability to have more acurate info on wheel speed differential.
Look in your manual and see if the term you are using Active TRAC is in it. later Robbie
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I'll agree to disagree as to which part of the CPU cuts throttle (TRAC or VSC) and leave it at that. I have never seen anything from Toyota in writing that mentions Active Traction Control adjusting throttle...but OK Robbie.

Yes, I am familiar with the "full name" of TRAC, A-TRAC, Active TRAC as being Active Traction Control.
**You and I are simply referring to the same system using differnet "terms".

Yes I am also familiar that in the FJC/GX they added sensors. Maybe you missed this in my post that you had a bone to pick with?

"That description from the FJ Forum is not correct. Both systems are known as "Active TRAC" per Toyota. It's us wheelers that choose the term when we write, TRAC or ATRAC.

The systems are the same. Again, it is Active TRAC.

Their are a few differences between years and model Toyotas. The differences are:

*Wheel sensors (for accuracy)
*Software (different for each vehicle type...programmed to accomplish different agendas...In a LC or FJ it's for traction first and there's no throttle cut. In a Sequoia it's slow it down to a stop via throttle cut first and then traction control if possible)
08-14-08 06:28 AM"

Regardless of model, sensors, 4-HI or 4-LO, the system Toyota uses is know as Active Traction Control. That's all I said on the post that you quoted.
 
powderpig said:
In high range in the FJC, TRAC will cut power on the engine as well as use brakes to have the vechicle move forward(in slippery situations, like snow and ice). VSC will also cut power when it senses a loss of stability or a bad corner turn(as well as a few other problems).
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Just read the enire section of the FJC owners manual. The manual makes it obvious which systems control what and a simple test can prove the conclusion.

Under "Traction Control" (both TRAC and A-TRAC): Only warnings/mentions of brake activity are noted.

Under "VSC" they mention ABS, Traction Control, AND Engine Control (throttle). They even state that the VSC CPU selects the brakes or engine to control the vehicle.

They do not mention Engine Control anywhere under "Traction Control". If Trac Cont utilized "Engine Control" they would have stated/explained it there as well.

The test? In 4-HI simply find a slick surface and use throttle to increase speed. No matter how much you use the RPM's will respond and speed will increase. In ice it may accellerate slower because brakes can fight you at the start. Snow, ice, mud....I can make the engine do whatever RPM's I want with the throttle.
I can fling mud all over the place at redline and you will never see the RPM's drop UNTIL you begin to slide or spin and VSC enters the picture with the engine throttle cut. The BEEP BEEP BEEP in the 100 confirms it. Not sure if the FJC has the beep.
 
I am currently in Los Angeles finishing up a long project. I will dig my notes out later this week to see if what I remember is correct.
But to me you have done again what you love to do John, twist stuff up. Only on the FJ Is the term A-TRAC used. The rest of Toyota's line uses Active traction control in the wording. While they could be constude to mean the same. They are similar but different. So your post #6 is wrong, while the post #2 from 5X5 is correct. You are funny some times.
See you soon on some hard trail. Besides, did you buy a FJC?
 
powderpig said:
I am currently in Los Angeles finishing up a long project. I will dig my notes out later this week to see if what I remember is correct.
But to me you have done again what you love to do John, twist stuff up. Only on the FJ Is the term A-TRAC used. The rest of Toyota's line uses Active traction control in the wording. While they could be constude to mean the same. They are similar but different. So your post #6 is wrong, while the post #2 from 5X5 is correct. You are funny some times.
See you soon on some hard trail. Besides, did you buy a FJC?
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All one has to do is read the manual Robbie. It's in there and it's very easy to understand. I'm sorry Robbie, if you think Traction Control (TRAC or I-TRAC)cuts throttle you are misunderstood or misinformed. No offense. You know 10000X more than me about vehicles though I do understand these systems quite well.

4-Hi, TRAC, there is no mention of "engine control" with TRAC
4-Lo, I-TRAC, there is no mention of "engine control" with I-TRAC
VSC, there is mention of "ABS" and "engine control" intervention

The systems work identical between Toyota vehicles and the only differences (as I stated before) are:

1. Software (programming)
2. Wheel sensors
3. Some vehicles have an "off switch"
 
John...do you really feel as though you know more than Robbie--someone who was not only a Trail Team leader on the FJC (and worked on them, wheeled them, and taught others to drive them) but as well probably the best known mechanic for 80 series LC's as well as 100 series LC's (when he was at Christo's)?

C'mon man. At some point, it is a good idea just to admit incorrectness and move on.

Christ, the guy is doing 80 series 1FZ HG's one a day for the past month for christ's sake....trust me, I've been sending him parts daily for a month!!

-o-
 
beno said:
John...do you really feel as though you know more than Robbie--someone who was not only a Trail Team leader on the FJC (and worked on them, wheeled them, and taught others to drive them) but as well probably the best known mechanic for 80 series LC's as well as 100 series LC's (when he was at Christo's)?

C'mon man. At some point, it is a good idea just to admit incorrectness and move on.

Christ, the guy is doing 80 series 1FZ HG's one a day for the past month for christ's sake....trust me, I've been sending him parts daily for a month!!

-o-
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Overall....no way, as I said above. In the case of traction control and VSC he is misinformed or misunderstood. Nobody can know everything.

To find out the facts it's very easy. It's all right inside the owners manual and in plain english.
 
Screen shots from the FJ manual:

Traction Control:

NOTICE: Only "brakes" get activated by "Traction Control" There is no engine/throttle intervention.

394981563_nSGwE-XL.jpg


2nd page:

394982329_DKDj3-XL.jpg


Active Traction Control:

NOTICE: Only "brakes" get activated by "Active Traction Control". There is no engine/throttle intervention. The name change? Possibly because "Ative Traction Control" is sold as an "option" on the 4WD FJ's. The systems work the SAME in 4-Hi and 4-Lo as ONLY the braking system intervenes.

394982290_gVx7v-XL.jpg


2nd page:

394982206_ZLsd5-XL.jpg


VSC: NOTICE: With VSC, the brakes play a part, traction control play a part, AND there is ENGINE control. Contrary to what Robbie stated, it is VSC that cuts throttle and NOT TRAC or A-TRAC. If TRAC and A-TRAC cut throttle the manual would mention it in those sections as well.

394982386_FxxCi-XL.jpg


Driving experience will show that in 4-Lo-locked (when VSC is disabled) you can do anything you want and the throttle will not intervene.
One can get fooled on ice and snow from a dead stop as the brakes activate ASAP and getting started takes added gas. If one wants they can spin all over the place on ice in 4-Lo-locked. Step on the gas and go!

In 4-Hi when VSC is active, throttle can and will cut if factors are correct.

All Toyota models operate the same way as stated above. Maybe in the Land Cruiser models they don't differentiate between TRAC and ATRAC because ATRAC is not sold as an option and/or they do not offer a rear diff lock and/or there is no 2WD mode in the Cruisers.

So once again.........the differences?

*Software programming for each model's designed purpose
*Wheel sensor qty (more in the FJC and GX...don't know yet about the URJ200)
*Is sold as an option or not

Same system, all vehicles.
 
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