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A-TRAC/TRAC/AUTO LSD Explained (Easy to understand, I hope!)

Discussion in 'Technical Chat' started by David K, Jan 19, 2010.

  1. Nov 22, 2012 at 7:00 PM
    #1001
    Jackass

    Jackass Well-Known Member

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    Thanks David. Good to know what my Truck can do. I really had no idea when I chose my TRD OR last week. Chose the OR because I don't like silly skewps and the "Sport" on a truck. btw, After reading this thread earlier today, I was motivated to find a place to OFF Road. Nonetheless, I found one but unfortunately my wife was screaming at me just like she did when I use to go 120+mph in my previously owned Nismo. We were just going up a steep gravel hill as she was also shouting watch out for the big hole. She was shaken by the experience as i was smiling like a boy who had just experienced his first kiss. I guess I was wrong to get rid of the sports car. My wife is not only afraid of speed but also crawling too. Doh! This is what happens when country boy meets city girl. fml
     
  2. Nov 23, 2012 at 9:19 AM
    #1002
    David K

    David K [OP] Well-Known Member

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    I hope you enjoy it as much as I... Remember with limited slip systems, even A-TRAC, that if you come to am obstacle that stops your forward movement: to give it the gas and turn your steering wheel from side to side if you wish to dive ahead (and it is safe to do so). It is like 'waking-up' the system when you put your foot into it... similar to loading up the torque converter in an automatic by stepping on the gas and brake simultaneously. The truck will crawl like a tank with all 4 tires powered. It is a beautiful thing! ;)
     
  3. Nov 28, 2012 at 12:43 PM
    #1003
    roadtared

    roadtared Well-Known Member

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    Tirse and drop-in K&N so far.
    I have a 2WD reg cab taco and want to be sure. Everything you have listed in 2WD is that applicable to 2WD models or is that only for 4WD's in the 2WD mode? Thanks
     
  4. Nov 28, 2012 at 12:47 PM
    #1004
    David K

    David K [OP] Well-Known Member

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    The 2WD modes apply to all. 2013 may have some changes but they seem to be only with the 4WDs.
     
  5. Dec 15, 2012 at 4:56 PM
    #1005
    Leggo

    Leggo slow is smooth, and smooth is fast.

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    is this normal?


    I posted about this before and nobody knew WTF was up, to me it seems that with the 12s there is no option to turn TRAC ON and VSC OFF while in 4H. My v6 was bogging badly while towing a stuck car off a slick muddy road (think hard pack slippery mud where ya dont "dig" ya just fish tail the front and rear and spin on top). I tried hitting the VSC button once and nailed the gas and went no where, it fealt like I had open diffs at that moment. Thats when I didn what I should have done at first and shfted to 4L locked the rear with ATRAC on and gave er hell. Pulled the car like a champ untill the idiot steered himself into some deep ruts, I gave him a LIGHT yank and broke something on his car. I got outta there after that......

    So ya, my 2012 does this too. Before all that happened, I thought that I could go from normal 2WD mode to 4H, and have my TRAC WITH OUT the VSC and engine regulation. But I hit the button, it turns TRAC OFF, I HOLD the button it turns TRAC OFF AND VSC OFF.
     
  6. Dec 15, 2012 at 5:43 PM
    #1006
    MonkeyProof

    MonkeyProof Power Top

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  7. Dec 15, 2012 at 7:54 PM
    #1007
    David K

    David K [OP] Well-Known Member

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    According to your signature/ vehicle info., you have a Sport...?:confused:

    Let me know if you traded up to an Off Road 4x4 so you can relate to my answers on what my Tacoma does. I will come back and give data, but do let me know which model, and year of your 4x4 Tacoma so I can best help... Thank you!

    Let me add that there may have been changes in the 2012 H4 TRAC system I have yet to see a tech sheet/ flow chart on... so until that comes out, just an educated guess that there now is TRAC and AUTO LSD with the same degree of engine regulation as they have in H2. 2009-2011 has TRAC in H4 that is the same as AUTO LSD in H2 (ie. no engine output regulation) in other words TRAC in H4 for us is like AUTO LSD, but on all 4 tires.

    The no regulation feature makes the limited slip stronger, allowing the truck to climb out of a stuck if one tire spins. With regulation (TRAC in H2) there is a combination of brake force on the spinning tire and throttle reduction to reduce the chance of spinning. This is fine for street driving in slippery weather, but off road we want POWER!:cool:
     
  8. Dec 15, 2012 at 8:06 PM
    #1008
    Leggo

    Leggo slow is smooth, and smooth is fast.

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    thanx, no I have a sport.I am getting flak over engine regulation in 4h. My truck does not seem to curb the engine rpm in 4h, but I have read threads were others swear their truck bogs down with throttle controls in 4H. If they are turning the steering wheel left and then right, would that kick in the VSC to curb the throttle back? I dont practice the left/ right thing so I don't know. this is the only reason I can think of as to why the engine would be restricted when in 4H and spinning wheels. I thought you want some throttle to get the TRAC (ALSD) to work effectively.
     
  9. Dec 15, 2012 at 8:16 PM
    #1009
    Leggo

    Leggo slow is smooth, and smooth is fast.

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    here is what is being said about my comment about engine NOT being restricted in 4H


    im not even arguing about just ATRAC. the incorrect thing stated by Leggo was that the engine doesn't limit throttle when in 4hi with trac and vsc on. which it does. anyone who has a truck with those features KNOWS it does, get stuck in the snow with everything on and in 4hi, it will NOT let you crank the fucking engine to the redline... I would call that LIMITING the throttle. idc how it does it, and Toyota can state in their manuals that ENGINE output is not regulated all they want, but the fact of the matter is that it DOES. anyone who's been stuck in snow/mud knows it.


    I guess I am wondering why my truck still revs up when stuck in 4H
     
  10. Dec 16, 2012 at 10:33 AM
    #1010
    David K

    David K [OP] Well-Known Member

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    I understand your concerns and observations... not in snow, but when climbing steep grades, I have put my pedal down to spin (well to move ahead) and nothing happens, as if the engine is regulated... but, I did not quit.. I mashed the pedal, cranked my tires left and right (to grab fresh terrain), and the truck 'woke up' and pulled me to the top... best way I can describe it... and this was in low range with A-TRAC on (no rear locker engaged). You can see this happening in one You Tube clip taken of me, called One Tri Hill... I get to the steepest point and I stop moving for a few seconds (I am mashing the gas pedal and turning my tires left and right)... then the truck responds and I continue up. However, this is with A-TRAC... which you do not have... so, all I can suggest is to use Low Range (which for you has no traction controls so no regulation... just to spin the tires and turn your tires left and right.

    In H4 (High Range, 4WD), to get the tires to spin, turn OFF the TRAC by stopping the truck, press and hold down the VSC SWITCH for a few seconds... lights will come on to tell you VSC (and TRAC) is OFF. They will stay off until you press the button again or turn off and restart the truck, or drive in an unsafe manner at which time the VSC will come back on to keep you from rolling over!
     
  11. Dec 16, 2012 at 10:55 AM
    #1011
    David K

    David K [OP] Well-Known Member

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  12. Dec 16, 2012 at 11:15 AM
    #1012
    HBMurphy

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  13. Dec 16, 2012 at 11:47 AM
    #1013
    Leggo

    Leggo slow is smooth, and smooth is fast.

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    I have never tried a hill climb, but I have tried in the snow (pushing a plow) and I get no regulation like that. Seems counter to what makes the TRAC actually work to me.
    So this chart is actually wrong? the part about 4H no regulation, trac on vsc on?[​IMG]
     
  14. Dec 16, 2012 at 12:01 PM
    #1014
    David K

    David K [OP] Well-Known Member

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    Paul: Yes indeed... that was over 2 years ago and not long after our epic Mission Santa Maria Baja adventure! Recently changed both differentials and transfer case fluids to Mobil 1 (75-140 in the rear diff and 75-90 in the other two cases). The rear looked fine, no metal pieces, the other two looked new, specially the transfer case oil... at 40,000 miles.
     
  15. Dec 16, 2012 at 12:08 PM
    #1015
    David K

    David K [OP] Well-Known Member

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    The hill climb was in Low Range with A-TRAC ON... the differentials are open and traction control only begins to brake a tire when the spin rate exceeds the opposite tire spin... to match the rotation speed (as a locker matches the rotation with gears instead of brake pressure).

    You are in High Range and do not have the hydraulic brake booster... so braking action is less forceful... and while I don't ever say the chart is wrong, I can only say there isn't supposed to be any regulation in high range 4WD TRAC... any restriction must be coming from braking... if the chart is correct.

    If you feel there is restriction, why don't you use low range, or turn TRAC/VSC OFF (as I mentioned before)? If you want some limited slip in low range, then perform the 4-low-trac mod.
     
  16. Dec 16, 2012 at 12:24 PM
    #1016
    Leggo

    Leggo slow is smooth, and smooth is fast.

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    Thanx david, I don't want to beat a dead horse here. I just want to verify whether or not engine regulation occurs when in 4H, TRAC on,VSC on. I have never experienced regulation but others are saying it does.
     
  17. Dec 16, 2012 at 12:29 PM
    #1017
    David K

    David K [OP] Well-Known Member

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    Let me know as you keep testing! The truck is an amazing off road machine... and while I have had 4x4s before with lockers on the back or center differentials, I have never felt as secure going into the sh*t off road as I have with this truck with A-TRAC.

    Just use the heavy pedal anytime the truck stops, but you know it is safe to move on... wake up the A-TRAC (if equipped) or the TRAC, as in your case with a SPORT.... and do the yellow wire (4-low-trac) mod so you can go further in low range!
     
  18. Dec 16, 2012 at 12:36 PM
    #1018
    David K

    David K [OP] Well-Known Member

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    The 'regulation' we feel as VSC corrects spin-outs could very well be braking and perhaps (even though Toyota says no) when the brakes are applied, the engine power is reduced?

    I would love to have TRAC in H4 without VSC... for the regulation as well as to kill the beep-beep-beep of the VSC alarm.

    In H2, we have TRAC without VSC up to 30 MPH when we engage AUTO LSD (traction control without regulation)... over 30 mph, the VSC comes on automatically.

    It would be sweet to figure out how to mod the system to give us 'AUTO LSD' in H4, even if only up to 30 mph! Maybe they did this for the 2012 model...?
     
  19. Dec 16, 2012 at 1:41 PM
    #1019
    Leggo

    Leggo slow is smooth, and smooth is fast.

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    But a straight push or pull, with wheel spin? Because Toyota defines VSC as corrective action during a turn condition. Could the TRAC be regulating the engine rpm during a straight pull, wheels spinning?
     
  20. Dec 16, 2012 at 1:51 PM
    #1020
    Leggo

    Leggo slow is smooth, and smooth is fast.

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    so you have open diff's when you hit the dirt? What is trac for then? I am so confused:confused:
     
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