TRAC - Traction Control by Bosch

I think throttle is regulated in 2WD to maintain directional stability, in 4WD, with the front tires pulling where they are pointed, this is not an issue. I still think Toyota should call it ALSD, leave TRAC for when my wife is driving in 2WD.

 

Great Crom... I appreciate your quest for knowledge since I too share that desire!

I only want to help fellow Tacoma drivers understand what they have in the '09 and newer TRD Off Road 4x4s is a completely different and superior traction machine than previous Tacomas. It may look the same as my 2005 silver 4 door on the outside, but how it glides over deep sand, and climbs steep mud hills (in H4 with TRAC or L4 with A-TRAC) is totally new and superior experience to my previous 4WDs.

My experience with the 2010, so far, is in the California desert, Baja desert and beach, and some steep rutted and rocky trails that Panda Jerk calls the 'Drug Airport' off Twin Oaks Valley Road in San Marcos. Hemi's use of A-TRAC is different, living in Canada... The Great White North!

 

Somewhat, but I only use the Off Road specific features, in sand, rocks, and mud. In the snow, with my BFG AT's, I find no need for anything but 4H so far. Unbelievable how much more capable these trucks have become. This is truck #6 for me, and nothing even comes close, capability wise, off road.

 

10-4, when I say A-TRAC I also mean the 2010 enhanced TRAC using the hydraulic brake booster. L4 (with A-TRAC) is now really for the steep steep grades to crawl on, not so much for traction or tourque, anymore.

 

David, Hemi,

I finally made headway with Toyota Corp. I made contact with Mr. Roger M. a Powertrain product specialist at Toyota Corporate.

We had a really good discussion. Here is a summary of what I was told:

There are two types of TRAC

1. TRAC with ignition retard, TRAC in 2WD
2. TRAC in 4WD. I specifically asked him if this was the exact same traction system as Auto-LSD. So in effect Auto-LSD on front and rear axles. Without reservation Rodger said yes.

I asked him about A-TRAC. I stated this: Toyota states that with A-TRAC, Off-road drivability is equivalent to having the center differential locked and a limited-slip differential on both front and rear axles.

He said he agreed with that statement.

He also confirmed that small note in the documentation regarding VSC always monitoring, e.g. so you go sideways at 40 mph (yaw rate large) and push the brake pedal, VSC will intervene even if it was disabled using the VSC off switch. He was funny, he said he had not yet had a chance to test it but he was well aware of detail.

It was a very positive experience dealing with Toyota Corp.

 

Do you have his e-mail ? Can you ask him about installing a real LSD (tretrac/clutch pack one) on the rear and if it will screw up VSC

 

Hi BlueT,

I did not get his contact info, I had to go through the Customer Experience Center. The first line of people will attempt to get an understanding of your problem and then they may to try and answer your question using very basic information that is contained in your owners manual. When they can't they'll create a case # and an expert will call you back in a few days.

I have to give them credit because they called 3 times before they reached me on the 4th try. No voice mail was ever left.

My advice is to call and just work the system. I would like to know your results as well.

 

Cool. The only point I do not agree with, is; ATRAC is far more aggressive, and "tighter", than any mechanical LSD. But it is not fully locked. It is in a class by itself, having most of the good aspects of lockers, as well as LSD's. TRAC is like LSD's at both ends, very, eerily similar, yet very different from ATRAC.

 

Hemi, Crom, others...

A-TRAC proved itself as awesome beyond belief in Baja this past weekend, on the Mision Santa Maria trail... I never touched the Rear Locker button. Climbing cliffs and fording 4 foot deep water... See the photos that HB Murphy and I will be posting in the Off Roading forum.

Thanks Crom for that news on the TRAC in 4WD being the same mechanism as AUTO LSD, and differentb than TRAC in 2WD. Just poor naming by Toyota calling both 'TRAC', I guess.

 

I told y'all that a month ago!
Just kidding......

 

That's right... Hemi knows!

I will be posting in the various A-TRAC threads soon about my trip to Mision Santa Maria this last weekend... Several others along had lockers (front and rear) and the A-TRAC out performed the trucks with Front Lockers, hands down... There is NO steering issues with the A-TRAC... I just kept going and going... rocks, mud, sand. The guys who had the front lockers had to turn off the lockers just to steer the many turns. I never used my rear locker, never had a need... with A-TRAC.

Still have a ton of photos to add to that thread... stay tuned!

 

I plan on soon creating a seperate thread for the Mision Santa Maria trip report as the one now is so full of photos it is very slow to open.

As for the A-TRAC, and TRAC in 4WD... they were outstanding on this most challanging 4WD trail.

NEW USERS of 4WD TACOMAS with TRACTION CONTROL:
Don't freak out at all the options or button pushing. Just go, and in H4 the TRAC is going to impress you if you have not driven a vehicle with limited slip front and rear before. The only reason to turn TRAC off is if you want to compare the new with the old and get stuck with tires fully inflated... or if you just want to fishtail around in loose stuff. The only button that needs to be touched is the A-TRAC when you go into L4, and want to go go go where you never dreamed of before. It will get you out of a stuck too, if you weren't using 4WD and the TRAC, or A-TRAC. Click on the first link in my signature for more details. Here is a sample from that thread:


Normal Mode (no pressing of switches):

2WD (H2): TRAC & VSC on. TRAC (Traction Control) uses brakes and regulates engine output to achieve LSD (Limited Slip Differential action). VSC (Vehicle Stability Control) keeps truck moving where desired, on slippery roads

4WD (H4): TRAC* & VSC on (*engine output not regulated)

4WD (L4): (no trac, no vsc)

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Short press of VSC OFF switch:

2WD (H2): AUTO LSD on (no trac, no vsc)

4WD: no change, from above

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Long press (hold 3 seconds) of VSC OFF switch (when stopped) for OPEN Differential(s):

2WD (H2): All off (no trac, no vsc, no auto lsd)

4WD (H4): All off (no trac, no vsc)

4WD (L4): no change (no trac, no vsc)

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Press A-TRAC (Active Traction Control) switch:

4WD (L4): A-TRAC on (creates the traction abilities of front and rear lockers while in Low Range 4WD). Unless pressed again, A-TRAC will always come on when shifted into L4, from now on.

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Press RR DIFF LOCK switch:

4WD (L4): Locks the rear differential. Can be used with or without A-TRAC activated. A-TRAC only active to 3 mph with the rear differential locked.