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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. Jun 23, 2013 at 8:54 AM
    #1281
    David K

    David K [OP] Well-Known Member

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    Exactly what I think the 2012+ has, 3 modes in H4... But why have a regulated TRAC in 4WD, maybe for slippery highways?

    2012+ 4WD owners, please compare driving in H4 with it in the standard mode 'TRAC' (regulated engine output to reduce spinning for a lite limited slip), and with it it the 'TRAC OFF' mode (full engine power, but brake action on spinning tires to create limited slip) by pressing quickly the VSC Off switch (button).

    It should be like the difference in 2WD between its regulated TRAC, and the AUTO LSD (TRAC OFF) modes>>>?!

    For off roading with the most traction:
    2WD: Use AUTO LSD (TRAC OFF) (quick push VSC button)
    4WD-HI (2012+): Use TRAC OFF (quick push VSC button)
    4WD-LO: Use A-TRAC (and the rear locker if extreme) (push A-TRAC button, once, push rear locker button if needed)
     
  2. Jun 23, 2013 at 9:35 AM
    #1282
    monkeyface

    monkeyface Douchebag, or just douche if we're friends

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    Yeah, probably so. Dunno if it's better than 2009-2011.

    The time I remember best I was merging onto I-70 and there was two 18-wheelers competing to see who could get the best momentum up the hill, taking up both lanes of I-70. I was thinking I have to beat those two by the end of the on-ramp or else I'll be eating their slush. Stomped on it in default 4HI and as I said above there was some cutting in and out. I believe I hit the on ramp in 2nd gear, and felt the cutting out in 2nd and each upshift into 3rd, and 4th.

    I did beat them to the merge, but thinking about it now I probably would have been better off one-touching the "VSC OFF" button. Of course, between shifting the manual and handling the steering wheel trying to find that "VSC OFF" button would be a PITA.

    She did OK, but the engine regulation may have hampered me some.

    As for 4LO, wish I had the A-TRAC . . . .
     
  3. Jun 24, 2013 at 7:38 AM
    #1283
    David K

    David K [OP] Well-Known Member

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    To those that reported here, the next best thing is the 4-LO-TRAC (or now 4-LO-'TRAC OFF') Mod!! :cool:
    This give the non A-TRAC Tacomas, the limited slip of TRAC/AUTO LSD/ TRAC OFF (now?) while in Low Range.
     
  4. Jun 24, 2013 at 1:16 PM
    #1284
    monkeyface

    monkeyface Douchebag, or just douche if we're friends

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    Ya know, that kind of opens up another can of worms - RE: the Yellow Wire Mod for 2012+. Does completing the YWM still have engine regulation in 4LO.

    I saw from this thread http://www.tacomaworld.com/forum/technical-chat/51946-4low-trac-23.html starting on page 23 and up to page 27 there were several people that did the YWM on 2012+.

    They said it worked fine, same benefit as 2009-2011, but it wasn't crystal clear if there was still engine regulation in 4LO after doing the YWM.

    If the 2012+ truck just goes with default 4HI mode and applies it to 4LO that would mean motor regulation (maybe). Utard mentioned on the 2012+ there is a third yellow wire as opposed to two on the 2009-2011. Cutting the same wire as 2009-2011 results in both dash lights unlit in 4LO ("squiggly OFF" and "TRAC OFF").

    So maybe, just maybe, cutting one of those other yellow wires would result in lighting up the "TRAC OFF" dash light. Only one way to find out I guess - experiment.
     
  5. Jun 24, 2013 at 6:01 PM
    #1285
    David K

    David K [OP] Well-Known Member

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    I nominate you! :D

    So, I guess in H4 the TRAC OFF light (2012+) = the H2 AUTO LSD light (in that both lights = no engine output regulation... ?

    It is just so weird, to call more TRACtion control in H4: "Trac Off"! However, you can see from the 2009 charts, that in H2 they call TRAC OFF = AUTO LSD ON. There just is no TRAC OFF light in H2 or H4 (2009-2011).

    In H4 we have normally what is called TRAC OFF (now), no buttons to push... but is called 'TRAC'! :rolleyes:

    Make one wish he were drinking!
     
  6. Jun 24, 2013 at 10:39 PM
    #1286
    monkeyface

    monkeyface Douchebag, or just douche if we're friends

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    I'll dig into the wires tomorrow, try some experiments. See what dash lights light up or do not light up. And I'll try to find some mud to see if the YWM still has engine regulation.
     
  7. Jun 25, 2013 at 8:23 AM
    #1287
    David K

    David K [OP] Well-Known Member

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    Great.. and just have fun with it. YWM = Yellow Wire Mod/ 4 LOW TRAC MOD (or maybe now the 4 LOW TRAC OFF MOD??? LOL
     
  8. Jun 25, 2013 at 10:37 AM
    #1288
    jvswaim

    jvswaim Well-Known Member

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    Apparently the only way to really understand all the 4WD modes of a new 2013 is to shell out $4000 for A-TRAC. If you're not an extreme offroader, do you really need A-TRAC? Are the normal modes for a 4WD without A-TRAC good enough for winter driving on paved roads and an occasional foray onto unmaintained, flat county roads? :confused:
     
  9. Jun 25, 2013 at 1:08 PM
    #1289
    brian0128

    brian0128 Well-Known Member

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    Someone that lives near the beach that has 2012+ with A-Trac should complete similar tests as the OP.
     
  10. Jun 25, 2013 at 6:03 PM
    #1290
    David K

    David K [OP] Well-Known Member

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    A-TRAC has nothing to do with what monkeyface and I are discussing. ALL 2012+ 4WD Tacomas have TRAC, TRAC OFF, VSC OFF modes in H4. 2009-2011 4WD Tacomas have TRAC and VSC OFF modes in H4. TRAC was changed.

    The name 'TRAC OFF' mode is new for 2012, but the SAME as what was called 'TRAC' in H4 before. Now the new mode is called TRAC in H4 and has regulated engine output, as it does in H2.

    A-TRAC is a LOW RANGE ONLY system, that makes the truck climb and progress over uneven or loose terrain that previously required front and rear lockers... a "super limited slip" the matches tire rotation across the axle to the same rate as the opposite tire, when and only when traction is lost.
     
  11. Jun 25, 2013 at 6:07 PM
    #1291
    David K

    David K [OP] Well-Known Member

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    See my reply above. A-TRAC is not involved in the changes made in 2012 to 4WD Tacomas. A-TRAC is a LOW RANGE ONLY traction system, as is the Rear Locker, both ONLY available in the OFF ROAD TRD TACOMAS since 2009. The Rear Locker has been available on the OFF ROAD TRD for over a dozen years... Before 2005, TRD was only the Off Road, as there was no SPORT TRD before 2005.
     
  12. Jun 25, 2013 at 6:24 PM
    #1292
    monkeyface

    monkeyface Douchebag, or just douche if we're friends

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    Absolutely all standard 4WD modes are good for winter driving. Or mud, gravel, whatever (a caveat is good tires - the stock Dunlops are not so good).

    A-TRAC is for 4LO only - the extreme off-roading. However, the truck is still a good hill-climber stock in 4LO.
     
  13. Jun 25, 2013 at 6:43 PM
    #1293
    monkeyface

    monkeyface Douchebag, or just douche if we're friends

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    I got the glovebox out, pulled the connector, inspected the wires. There wasn't much slack in the wiring harness, and my soldering gun went bad on me so I'm not gonna fool around until I get a new one.

    Then, I f'd up and didn't reconnect the wiring harness til I started the truck again, therefore throwing codes. So I had to hook up the OBDII to clear the codes. Called it a day until I get the new soldering gun. Apparently, this was not my day.
     
  14. Jun 25, 2013 at 9:23 PM
    #1294
    jvswaim

    jvswaim Well-Known Member

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    I was referring to your discussion of the YWM which is done, as I understand it, because TRAC is turned off in 4LO giving open diffs in 4WDs without A-TRAC. But YWM isn't necessary if you have A-TRAC because it and it's companion, the elocker, give you all the traction control needed across the axles in 4LO.
     
  15. Jun 26, 2013 at 8:15 AM
    #1295
    David K

    David K [OP] Well-Known Member

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    That is correct! :)

    The 4 HI mode with (non regulated) traction control does more for climbing traction than 4 LO with no traction control. I would never use L4, without A-TRAC on... The really rough places where I would want to crawl slowly (in low range) have deep ruts and loose rocks where my tires would spin from loss of contact. Traction control (A-TRAC, TRAC, etc.) diverts lost power from a spinning tire to a traction tire... and I keep on going. :D
     
  16. Jun 26, 2013 at 11:29 AM
    #1296
    jvswaim

    jvswaim Well-Known Member

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    Now that's what I needed to hear, since winter road driving and muddy bad road driving are my only reasons for buying a 2013 4WD or not. I was beginning to think that if you didn't have A-TRAC, then the 4LO with open diffs was not much better than a 2WD with an LSD. So, if A-TRAC in 4LO is mainly just for extreme off-roading, then I could pass on the $3995 TRD OR pkg which apparently also requires a V6. That means I can get into a 4WD AC 2.7 5spd with no pkgs or accessories, for $25,050 msrp less discount. Per your tire advice, I could upgrade, and apparently be good to go! :)
     
  17. Jun 26, 2013 at 11:36 AM
    #1297
    jvswaim

    jvswaim Well-Known Member

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    So if you didn't have A-TRAC, then you would do your climbing in 4 HI with TRAC on, rather than 4 LO with open diffs, even for slow crawling situations?
     
  18. Jun 26, 2013 at 12:35 PM
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    rbishopp

    rbishopp Well-Known Member

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    I've lived in the Northeast all my life and never anything fancy. I have the base 09 tacoma 4x4 and I know it will make it through everything big momma can throw at me. Save you cash for cool fun stuff.
     
  19. Jun 26, 2013 at 1:55 PM
    #1299
    jvswaim

    jvswaim Well-Known Member

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    Now that's music to my ears. If a base 4cyl 4WD for $24K will work, why pay $31K to get a V6 I don't want, just to get A-TRAC, which I don't really need.
     
  20. Jun 26, 2013 at 4:38 PM
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    HBMurphy

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    Now let's explain the wheel speed sensor - specifically why the cost $200!!!! lol :'(
     
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