TRAC - Traction Control by Bosch

Traction control is designed to help the truck accelerate without wheel slip. Typical engagement usually involves the driver operating the accelerator pedal in a rough manner and the drive wheels are on different surfaces (pavement/sand, pavement/snow, pavement/ice, etc. These statements pertain to TRAC in 2WD. Watch the video for a visual demo.

http://www.youtube.com/watch?v=OfXB0lCmXAM

TRAC in 4WD does not regulate the throttle, therefore it operates differently than TRAC in 2WD. People do use it as an off-road tool to maintain traction. See comments below.

 

My Dad worked for Bosch's power tool division for 10 years. I never realized till after he stopped working there how much random stuff they have their hands in. From dishwashers to power cells used on the ISS.... half the stuff in my Tacoma, and the 10k worth of power tools in my garage.

Honestly till I went to college about 8 years ago all I thought they made were Dremels, drills, and impact hammers.

 

Too funny!

 

good demonstration.

 

It sure makes a difference in sand... no more deflating tires to gain traction!

 

My wife has a traction control system (TCS) in her minivan. TCS works Ok as long as one tire has constantly good traction, or both tires have little traction. Once on icy incline TCS becomes not only useless but needs to be turned off.

 

Say you were in a bug sloppy mud situation. Do you want to have the TRAC on or off in 4HI? I have always been told and experienced that you want high rpms and wheel spin in that kind of situation. But with open differential (trac off) then I dont see how that is beneficial. Is there ever a "good" time to turn the TRAC off in 4HI by pushing the VSC button and turning TRAC off?

 

No. I would turn off both TRAC and VSC in that situation. Just like our owners manuals tells us to do.

EDIT: My statement incorrectly referenced the owners manual which spoke to TRAC operations in 2WD.

Yes. I do this when I don't want TRAC to interfere with my off-roading experience. I wheel with open diffs in 4Hi quite often almost exclusively. This is especially true when I want to do burn outs or donuts.

TRAC really isn't designed as a tool for offroading. It is designed to keep the vehicle going strait when starting from a stopped position.

EDIT: TRAC in 4WD is for offroading while TRAC in 2WD is not.

 

Wow, are you sure...? Hemi or another may be popping in here to correct that statement Crom! TRAC is the greatest off roading tool Tacomas have added since 4WD... and I am om my 3rd Tacoma, and have nearly 40 years of four wheeling experience.

VSC is what keeps your vehicle going straight (or the direction you are steering to), NOT TRAC... which is a lmited slip system to get you going. (period). VSC uses TRAC (and other components), but TRAC is its own animal.

In 4WD High Range, there is NO engine output regulation in TRAC... that's only in 2WD.

In 2WD you have AUTO LSD (TRAC OFF MODE) which also has NO engine output regulation.

AUTO LSD in H2 and TRAC in H4 are both the same: Limited Slip without engine regulation.

TRAC in H2 has regulation.

The names Toyota uses are part of the problem!

TRAC OFF MODE is AUTO LSD on (ie better TRAC) in H2

VSC OFF MODE is open diferentials in H2 and H4
H4 normally has TRAC but without regulation, unless you hold the VSC OFF switch in for 3+ seconds while stopped.

 

Yes.

Please reread and rewatch the video in post #1.

I disagree. I believe that A-TRAC and lockers which are designed for off-road use are the greatest tools we have.

I don't question your experience. But I think you may be misunderstanding when TRAC is actually engaging on your truck.

Please take a look at Rolands truck in this video. He did the TRAC in 4Lo mod (yellow wire mod). As far as I know it is one of the best examples of TRAC engaging on video. Just look at how much wheel spin is necessary for TRAC to engage!

http://www.youtube.com/watch?v=G0AH1yIUp0A&feature=player_embedded

Is that really happening for you on your truck too?

 

My sand experience with the new truck was in 4 HIGH, which is TRAC without enginge output regulation ('AUTO LSD' on all four, if you will)... THIS is what is different over my '05 Tacoma. This is what is the greatest improvement in Traction since 4WD... IMO.

A-TRAC is awesome, but in LOW RANGE only, is it available... Your topic is TRAC which is two different modes with the same name (bad): TRAC in H2 with engine regulation and TRAC in H4, with no regulation.

TRAC does allow some spin, but it works. Now, only the OFF ROAD Tacomas with A-TRAC have the hydraulic brake booster... which works with TRAC in H4... maybe that is where it outshines other Tacomas with TRAC using a vacuum brake booster?

If someone is using TRAC in L4 because they did the yellow wire mod, it means they don't have A-TRAC and they don't have a hydraulic brake booster. Could explain the added wheel spin?

 

If Roland didn't have TRAC and was in 2WD, he would have been stuck right there, and needed to roll back until both tires were on the ground. If he was in 4WD then the front tire(s) would keep him going. I have not noticed any amount of wheel spin like that with my truck, unless I turned off the LSD (VSC OFF MODE) and made it open like my '05 Tacoma.

 

David have you tried your Tacoma without TRAC in the sand?

My 4WD sand experience has been very positive and I wheel in "VSC-OFF Mode" (open diffs).

Without testing we can only speculate. According to the Toyota tech document the function of the brake booster is to increase force to the brake pedal.

I don't think so. If you look at the A-TRAC video thread I started, it will show that while in 4WD if one wheel spins in our trucks that translates to being stuck.

 

Crom, I have stated many times about the difference between the 2010 and the 2005... YES, I HAVE turned off TRAC (VSC OFF MODE) in the sand, tires at 32 psi and the truck bogged down and stuck! This was my first time using A-TRAC to get out... and that worked fantastic!

Once I was out, I went into H4 (TRAC ON) and drove about easily... THERE IS A BIG BIG DIFFERENCE between TRAC ON and OPEN DIFFERENTIALS (TRAC and VSC OFF) in Baja Beach Sand.

Sorry amigo, but you are very, very wrong about A-TRAC. The videos of true A-TRAC (not yellow wire mod TRAC in L4), and MY personal experience high centering the rear end, with only one or two tires in front having traction, facing uphill, PROVES A-TRAC will pull the truck out with ONLY ONE tire having traction... Didn't you see the Tundra A-TRAC demo video I posted???

Where is 'Isthatahemi' when you need him? If you don't believe any of my personal tests or my research here and on the tech sheets, will you believe hemi???

 

Nope. it is designed to send power to wheels with traction, in any situation. The first video disproves what you are saying. Besides TRAC in 4H is not traction control, it is torque distribution. Clearly it is not designed primarily to keep the vehicle straight, it would regulate throttle, which it doesn't. The only traction control our trucks have, is the default 2WD setting.

That vehicle only kept going because he had TRAC, otherwise it would have been game over. You have proven your point to be incorrect.

The fact that you are not ever getting stuck when wheeling, is a little strange. Quite simply, there is no comparison to TRAC on, and TRAC off. I fail to understand how you can think 2 wheels spinning is better than 4.

I consulted with Toyota Engineers at the corporate level, on this point before getting my 2010. The hydraulic booster is integral to the ATRAC system, so the booster is not just to increase pedal pressure.

I have respect for Crom, he is very helpful. But in this case I know him to be flat out wrong. My SR5 was useless off road until I activated TRAC in 4L. How can a system that is similar to ATRAC be a bad thing?
David, as a fellow off roader I agree 100% with your assessment.

 

Thanks Hemi... I am not trying to be a smart burro, but I want the facts to be known and understood. I have been learning and modifying my understanding of the drive modes since I got my truck in December, and all of you guys here on TW have been great. It just seems like Crom was saying new things that just threw out everything I had come to know at this point, and it didn't make any sense.

I hope that Crom will join me in Baja or the desert some day where I have seen TRAC and A-TRAC perform and out perform open differential mode. As you say, 4 wheels with torque beats two, every time!

So, should Toyota stop calling TRAC 'TRACTION CONTROL' (in H4), and call it TORQUE CONTROL instead?

 

David, I believe what you say. It's just that my experience is just different than yours. I guess the smoking gun I am looking for is for someone to get stuck in the sand and have TRAC get them out or at least confirm that that TRAC is indeed engaging while driving in the sand. My theory is that because the friction characteristics of the sand is the same for all drive tires there is no reason for TRAC to engage. And that is why I PM'd you before the conversation in this thread started.

David we both have a solid understanding of A-TRAC. And I am sorry but I should have been more clear when I wrote: If you look at the A-TRAC video thread I started, it will show that while in 4WD if one wheel spins in our trucks that translates to being stuck.

I should have wrote:If you look at the A-TRAC video thread I started, it will show that while in 4WD Lo (no A-TRAC), if one wheel spins, that translates to being stuck.

I was referring to the first video in my first post in that thread in which case I demonstrated that while in 4Lo (no A-TRAC) if one wheel spins the truck is stuck. In the same video I pushed the A-TRAC switch and became free when I pushed the accelerator.

Like I said above I believe you and have no reason to doubt you. My sand experience has been different than yours. I plan to do some extensive TRAC tests sometime in late June or July which I will video record for the benefit of all. If you care to, we could even go together.

The point I was making was that there are times where TRAC may be inappropriate and should perhaps be disabled.

I'm sorry but you misread my post. I stated that Roland's truck had TRAC enabled in the video.

I didn't write that! I have gotten stuck many times in the rocks and seriously rutted roads, just not in the sand with full psi which is where David and I were disagreeing. My experience in the sand has been different from his that is all.

For what it's worth I have written Toyota seeking to speak with a subject matter expert on all the traction systems to clarify what I refer to as gray areas. If it's not too much trouble PM me your Toyota contact or at least kindly explain to me in detail how it was that you made contact so that perhaps I can have my own questions answered.

Also any technical 'traction system' literature you may have received excluding the 2009 brake tech document that you care to share would also be very helpful.

I have respect for you as well. There is nothing wrong with TRAC, I just choose not to use it in 4Hi.

Me too. It would be an honor to wheel with you in Baja.

 

Great... Perhaps the sand you are wheeling in is not the same as what I usually drive in... and that is the deep beach sand found on the Sea of Cortez (Gulf of California) side of Baja... It is a mix of coarse sand and crushed shells... you sink! With TRAC, deflating was not needed, without (VSC OFF MODE) I soon bogged down (because tires were at 32 psi).

Now, sand conditions change and the sand in the desert near Ocotillo is far different than beach sand... Normal, open diff. 4WD is usually not a problem in our desert sand, unless you want to climb a dune... then deflating tires or having all four wheels getting torque will help.

Hemi is making it clear what we have all seen, that with open differentials, once traction is lost, torque goes to just two tires (one in front and one in back) and that just digs you in worse. With the TRAC and A-TRAC, torque goes to all four tires and thus we don't loose traction to a point where just two tires spin us in or down!

You need to come camping with me to Baja to see THAT kind of sand, or you need to find sand in the desert that your Tacoma will get stuck in at 32 psi... THEN you too will see how superior TRAC is in H4 compared to open differentials.

Thanks for the opportunity to discuss this system... it is truly awesome!

 

I have 4 videos of that exact scenario, while using TRAC. PM me and I can Email them, or if someone can tell me how to post them, I will.

 

David, Hemi,

I concede that TRAC in 2WD, is not the same animal as TRAC in 4WD. I have amended my opening post to clarify some comments for anyone that browses this thread in the future.

If I am asked how TRAC works off-road I think it's only fair to state state that I have not tested it enough to really know, but will most certainly point out and refer them to both of your positive experiences.

Also, I have known about the throttle regulation difference in TRAC 4wd vs TRAC 2wd for a while now, I just have not ever seen Toyota state why--They state that it is but they have never explained why. I know we have told each other many times over. But we are all peers here, and I am looking for something more.

One of the more interesting details I discovered last month was a hydraulic diagram that illustrated TRAC in 2WD in the pressure increase solenoid mode. In that mode, when wheel slip occurred TRAC was braking both rear wheels simultaneously. I theorize that TRAC in 4WD probably does not do this. It probably brakes only one slipping drive wheel.

The Toyota technical document does not say anything about how TRAC functions in 4WD and that is what I want Toyota's clarification on. If I make progress with them or obtain any new information I'll be sure to share it.

Thanks to the both of you for a great healthy discussion.