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Understanding Driver Nannies - A Cheat Sheet

Discussion in 'General Tundra Discussion' started by iamkeith, May 31, 2019.

  1. May 31, 2019 at 3:00 PM
    #1
    iamkeith

    iamkeith [OP] New Member

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    I was having trouble understanding and remembering how the various driver nanny systems work in my new Tundra, so I created a cheat sheet to laminate and keep in the cab for handy reference - at least until I commit it to memory. This might be simple for those who are accustomed to driving "smart" vehicles, but I thought I'd share it in case it could help a few other luddites like myself:

    [EDIT: SEE FURTHER DOWN IN THREAD FOR UPDATED VERSION, WITH ADDITION OF "A-TRAC" FEATURE, AND DISCUSSION OF WHY]


    NannyCheatSheet.jpg
    - This is for a 2018 4WD truck. Earlier trucks would be similar, but without the PCS and BA systems. 2019 would be similar, but with the addition of something called "Smart-Stop" (SST)? I don't understand how the later differs from ABS or BA, though.

    - If you see something incorrect, feel free to let me know and I can update if interested.

    - Obligatory disclaimer: Use at your own risk. May contain errors, and definitely contains simplified and paraphrased descriptions which are not a substitute for reading your own user's manual.

    - .JPG and .PDF versions attached​
     

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    Last edited: Jun 1, 2019
  2. May 31, 2019 at 3:15 PM
    #2
    JMB

    JMB Not new, just a little old.

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    Huh, the 2018s don't have ATRAC?
    This is from my 2013 owner's manual.

    ■ A-TRAC (Active Traction Control) for 4WD mode on 4WD
    models
    Maintains drive power and prevents all wheels from spinning when
    starting the vehicle or accelerating on slippery roads.
     
  3. May 31, 2019 at 3:24 PM
    #3
    JMB

    JMB Not new, just a little old.

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    This is from a 2nd gen owner's manual. There's a thread on here somewhere about it.
     

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  4. May 31, 2019 at 4:40 PM
    #4
    iamkeith

    iamkeith [OP] New Member

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    Interesting. I just found a good thread that seems to suggest that TRAC is the 2WD version and ATRAC is the 4WD version of the same thing, but the later works on all wheels:

    https://www.tundras.com/threads/traction-control-everything-you-want-to-know.21697/

    However my manual seemed to say pretty clearly that this is not the case, and doesn't even mention the term ATRAC. I was surprised myself - even though my prior Tundra pre-dated all of these options. I didn't pay much attention when shopping because I just assumed I'd need to install real limited slip differentials or lockers.
     
    JMB likes this.
  5. May 31, 2019 at 4:53 PM
    #5
    iamkeith

    iamkeith [OP] New Member

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    JMB likes this.
  6. May 31, 2019 at 5:04 PM
    #6
    Macreggg

    Macreggg TRD No

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  7. May 31, 2019 at 5:19 PM
    #7
    iamkeith

    iamkeith [OP] New Member

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    Well, for a moment I thought 2018 might have been an anomaly - coinciding with the addition of PCS - but the 2018 brochure references ATRAC too.


    https://www.google.com/url?sa=t&sou...FjAAegQIAxAB&usg=AOvVaw0hdalOk5IA5OPbXP_lQNvO

    I'll post some excerpts from my manual when I get home. Very perplexing why there's so much contradictory information out there. Especially coming from Toyota themselves. Now that I'm looking - and between forums iH8mud, tundra talk and here - i can find claims both ways.

    So if it has ATRAC but doesn't have a button to turn it on like Tacomas, does that mean it automatically supplants TRAC in all 4WD modes?
     
  8. May 31, 2019 at 5:20 PM
    #8
    JMB

    JMB Not new, just a little old.

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  9. May 31, 2019 at 5:22 PM
    #9
    JMB

    JMB Not new, just a little old.

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    Yes, that's my understanding.
     
  10. Jun 1, 2019 at 10:29 AM
    #10
    iamkeith

    iamkeith [OP] New Member

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    OK, here's another version of the Cheat Sheet with the addition of the A-TRAC feature.

    I've read fifty different threads and watched a dozen youtube videos trying to explain the operation of the traction features in particular, but they all seem to contradict each other in various ways, most don't include explanations straight from Toyota's mouth, and none offer at-a-glance operational instructions like I'm trying to create for myself with this cheat sheet. I could still have some of this wrong, but I actually think I might finally have it:

    Three big things that make this (the traction control part) such a debated and mis-understood topic:

    1) The Tundra Owner's Manual includes no mention of having an A-TRAC system whatsoever, nor instructions on how to operate it. As per the link above, this leads some dealers to even claim that it doesn't exist. However the brochures/sales media, anecdotal evidence from people who understand how to utilize it, and input from contributing technicians tells us that it DOES in fact exist. But, unlike some other older models (including perhaps 4-runners, Landcruisers & some Tacomas?), the A-TRAC is always operational in the Tundra when in one of the 4WD modes. It is not necessary to turn it on so there is no "ATRAC" switch, but it can't be turned off either.

    2) Toyota kind of boxed themselves into a linguistic corner by constantly adding new nannies and by trying to give them all unique acronyms which, taken together, are no longer intuitive in their meanings! This might be why they didn't even try to address it in the Tundra Owner's Manual. "A-TRAC" and "AUTO-LSD" are basically similar in function, with the obvious difference that the former applies to both axles simultaneously. However "TRAC," (Automatic Traction Control, as it's termed in the Tundra Manual) which SOUNDS like it should be comparable to "A-TRAC (Active Traction Control)," is something entirely different. A-TRAC & Auto-LSD refer to the simulated limited-slip differentials, whereas TRAC refers to the part of the system that retards engine timing and restrains engine output, to try to stop a vehicle from spinning out.

    3) The Owner's Manual (and dash indicator, for that matter) describes the process for using the Auto-LSD feature as if the operator needs to deliberately turn something "on." (Achieved by a single push of the traction control button.) However, what you are REALLY doing is turning something off! The Auto-LSD feature is actually on by default, and pushing the button simply turns off the TRAC feature which - as noted above - is the thing that reduces engine output. I can't figure out if Toyota explains the process in such a convoluted way out of a mis-translation due to some East-West language/logic barrier, or if they're being deliberately misleading in an effort to get average drivers to use the vehicle in a manner that they think is most fool-proof and safe.


    [EDIT - ONE MORE, MINOR REVISION BELOW]
    NannyCheatSheetV3.jpg
     

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    Last edited: Jun 29, 2019
  11. Jun 1, 2019 at 10:40 AM
    #11
    iamkeith

    iamkeith [OP] New Member

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    Here's the factory explanation of traction systems from @JMB, above, in a web-viewable format, which seems to corroborate my explanation of TRAC, A-TRAC and AUTO-LSD above. This is the most validating piece of information I've seen - thanks! The current Tundra manual offers nothing nearly as clear.

    VSC Matrix 2nd gen tacoma.jpg
     
    Last edited: Jun 1, 2019
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  12. Jun 1, 2019 at 10:49 AM
    #12
    iamkeith

    iamkeith [OP] New Member

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    While I'm at it, here's a logic/flow-chart explanation of how the Brake Override system works. It's from a Prius or something, but I think it's basically the same. Because there are actions you can perform to defeat it, it's worth understanding if you want to have better control of your truck. People who try to drive their Tundras aggressively using a two-foot technique in technical terrain complain about this system fighting them. It turns out that you can prevent some of the conflict by: 1) Avoiding pressing the brake pedal too firmly; or 2) Using the emergency brake as a sort of hill-holder feature, instead of the regular brake.
    Toyota_BrakeOverrideSystem_Page_1.jpg Toyota_BrakeOverrideSystem_Page_2.jpg
     
    Last edited: Jun 1, 2019
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  13. Jun 1, 2019 at 11:14 AM
    #13
    iamkeith

    iamkeith [OP] New Member

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  14. Jun 1, 2019 at 3:27 PM
    #14
    iamkeith

    iamkeith [OP] New Member

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    Here's another article and diagram (referencing 2008 Tundras but still relevant here) that gets shared on the forums but is nonetheless incorrect - or is misleading at best, just like the Owner's Manual. The guy actually DOES describe the process accurately in the text part of his "normal mode" real world example, but the parenthetic part of the heading and the accompanying chart are wrong.

    In "normal" mode, the Auto LSD function is not 'off.' It's doing the precise thing it's designed to do: selectively applying brakes to wheels without traction, so that the wheel with traction can take over. It's just that it can't be utilized to get you un-stuck because the engine is being prevented from developing any power. Contrary to this chart AND the current Owner's Manuals, pushing the button doesn't turn 'on' Auto LSD - it turns 'off' TRAC so that the engine is no longer restricted.

    ( On a different note, I also find statements like the one in his last real world example (two long-pushes on VSC button to turn off all nannies) to be pretty offensive:

    "... but this should only be done by experienced drivers in very specific circumstances."

    In other words - even though this mode simply renders the Tundra to behave exactly like every other car that most of the population has owned or driven in the last 65 years (except perhaps your high-school muscle car with the true posi/limited slip rear end, and except for the fact that it does add anti-lock brakes), 'you are not capable of handling it.' Just like 'you're not capable of understanding the operation of the systems if we describe the process accurately.')

    Tundra VSC 21 (2).jpg
     
    Last edited: Jun 1, 2019
  15. Jun 29, 2019 at 10:57 AM
    #15
    iamkeith

    iamkeith [OP] New Member

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    One last, minor revision to the cheat sheet for anyone who cares. Added description for "EBD" (Electronic Brake force Distribution) system, and realized that the "Brake Override System," described in the manual, is in fact the "SST" (Smart-stop Technology) described in the sales brochures.

    NannyCheatSheetV6.jpg
     

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    Last edited: Jun 29, 2019
  16. Jul 27, 2020 at 5:49 PM
    #16
    1794-BlackTundra

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    Thanks @iamkeith for putting this together!!! THIS IS rocket science! :facepalm:
     

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