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Discussion Starter #1
Ok, doing some research the Toyota is actually a full time AWD vehicle with a 50/50 split of power between the rear and front and sending 25% to all wheels. There is no "locking" of the differential or Transfer case. That is what I expected from this vehicle. I also have a Ford Explorer which is a true 4 WD vehicle and the only time i have actually used 4WD was in deep sand and NEVER used 4 WD Low range.

Now for my question, how does this compare to that vehicle in 4WD high? If all 4 wheels are getting equal power what happens when one wheel slips or spins? Do the other three continue with the same power (75%) and the spinning wheel gets the brake applied?

The reason i ask is there is an explanation for the AWD system on this except for my question above.... anyone want to explain it?
 

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From what I have read, Toyota's AWD in their Highlanders is 50:50 front:rear fixed torque split. Whether that means torque is distributed to the slipping axles or wheels that lose traction is not answered.
By the term "fixed" though, I would suspect the torque per tire/axle is fixed and does not change. Perhaps the "Snow" feature in these vehicles changes something?

Funny thing, on the back of my HL is a nice shiny chrome emblem that says 4WD. Perhaps that has to do with the "Snow" traction option in my vehicle?

Here's a very interesting article and video about 4WD versus AWD:
http://www.rubicon-trail.com/4WD101/difference_4WD_awd.html
 

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If you read through the AWD explanation in the sticky, you'll find it did address your question (for the highlander). While power is variably applied between front and rear, it uses the brakes on each wheel to prevent wheel spin. So if 50 percent of the power is sent to the rear, it's still sending that power to the right rear even if it begins to spin but it will use the brakes on that right wheel to keep it from spinning. Kind of like stepping on the gas pedal and the brake at the same time, except it does it on a wheel-by-wheel basis.

Did that answer your question, or did I misunderstand your question?
 

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^ Moose,

Why do most descriptions call it AWD yet on Toyota's site it's called 4WD? There's a difference between AWD and 4WD. Why Toyota has discrepancies to their description is curious.

I figured it out from the Sticky-Video

It's not 4WD. It's Full Time AWD, but Toyota likes to call it 4WD for some reason. BIG DIFFERENCE.
 

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EDIT: Disregard what I said below. I didn't know what I was talking about at the time.:D

AWD systems send power to all 4 wheels constantly. Take Subaru for instance, they're sending power to all 4 wheels all the time. Toyota doesn't do that. The 4wd highlander is a 2wd vehicle that becomes 4wd when circumstances warrant it (ie when it senses wheel slippage). Thus, it's a 4wd system.
 
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That makes perfect sense. A 2wd vehicle that is only part time 4wd is considered a 4wd vehicle. :confused:
Actually, my tacoma is a 2wd truck that is only a part-time 4wd vehicle. The highlander is a full-time 4wd vehicle. You cannot turn off the 4wd in it. So I use the term 2wd loosely. Take the situation where you're traveling down the freeway on dry pavement. No wheel slippage, therefore only the front wheels have power...thus you're in 2wd mode. Now if you hit sand and the front wheels slip, it kicks in the rear wheels. Full-time 4wd system. My tacoma will let the rear wheels slip in this instance and will stay in 2wd mode unless I manually flip a switch to put it in 4wd. When I put it in 4wd, it can only turn all 4 wheels. No 2wd mode available unless I turn off the 4wd. Thus, it's a part-time 4wd system (part time being only when I turn it on/off). You cannot turn off a full-time 4wd system. It's just like it states, it is full-time.
 

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Discussion Starter #8 (Edited)
If you read through the AWD explanation in the sticky, you'll find it did address your question (for the highlander). While power is variably applied between front and rear, it uses the brakes on each wheel to prevent wheel spin. So if 50 percent of the power is sent to the rear, it's still sending that power to the right rear even if it begins to spin but it will use the brakes on that right wheel to keep it from spinning. Kind of like stepping on the gas pedal and the brake at the same time, except it does it on a wheel-by-wheel basis.

Did that answer your question, or did I misunderstand your question?
Thanks.. but kind of. What I was questioning is Toyota says that there is 25% power going to each of the 4 wheels all the time. Hence AWD or "full time 4wd" with no low gear... that part I understand. What I meant to say or ask is if 25% power goes to each wheel all the time, if one wheel slips does 100% of the power go to that wheel and none to the others until breaking occurs or does the 25% per wheel stay constant regardless of slippage or not?

Also, if I turn off TC/VSC will all power go to the spinning wheel or [still] to all 4 wheels regardless and 25% to each?
 

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Discussion Starter #9
Actually, my tacoma is a 2wd truck that is only a part-time 4wd vehicle. The highlander is a full-time 4wd vehicle. You cannot turn off the 4wd in it. So I use the term 2wd loosely. Take the situation where you're traveling down the freeway on dry pavement. No wheel slippage, therefore only the front wheels have power...thus you're in 2wd mode. Now if you hit sand and the front wheels slip, it kicks in the rear wheels. Full-time 4wd system. My tacoma will let the rear wheels slip in this instance and will stay in 2wd mode unless I manually flip a switch to put it in 4wd. When I put it in 4wd, it can only turn all 4 wheels. No 2wd mode available unless I turn off the 4wd. Thus, it's a part-time 4wd system (part time being only when I turn it on/off). You cannot turn off a full-time 4wd system. It's just like it states, it is full-time.
Maybe I read this wrong... you are saying the Highlander is 2wd unless it needs it? Correct me if I am wrong, but I do not believe there is a viscous coupling or anything like that... just a transmission with a front, middle and rear differential. I believe all wheels are powered at all times...but I may be wrong.
 

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Maybe I read this wrong... you are saying the Highlander is 2wd unless it needs it? Correct me if I am wrong, but I do not believe there is a viscous coupling or anything like that... just a transmission with a front, middle and rear differential. I believe all wheels are powered at all times...but I may be wrong.
Actually, I read it wrong.:headbang: I hadn't realized the newer highlander and sienna had switched systems. Sorry about that.

I was describing the full-time 4wd system used on the RAV4. Evidently, Toyota switched to full-time AWD on the Sienna and Highlanders. But you still can have only 50% going to the front and 50% going to the rear (all the time in this case). I still think your question is answered (if not by omission) in the article. Unless you have a limited slip differential you can get all power going to one wheel (which I don't believe we do because what's the point with an AWD system and electronics controlling each wheel's spin...they even removed them from the Tacoma in '09 in exchange for an e-LSD using the brakes at each wheel). But in the case of their AWD system, it only sends 50% to each axle. Since only 50% of the power can go to the rear axle, you can't get more than 50% going to one rear wheel. But if you test it out on a slippery surface (like I did with out old RAV4 years ago), you'll find that the systems engage so fast that you'll hardly notice it (if at all with the newer electronics). I'll be testing it out during the first snow storm this winter. Always good to test everything out so you know what it will do in an emergency and to know what it feels like.
 

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Discussion Starter #11
Last year was the best snow year we ever had in NJ, but I did not have the Highlander... Just my Explorer. The Explorer plowed through 30" of untouched (powdery) snow without a hiccup. Do you think the Highlander is capable of this as well? I sure hope so, because I was up at 5 AM dressed and ready to go 4 Wheeling with my son and daughter! I never got stuck in the 6 years I owned the Explorer and hope the experience is the same in the Highlander...anyone want to chime in?
 

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As long as you don't stop for any length of time and have good tires, you'll be fine. If you stop, you can get stuck no matter what vehicle you're in. I did that in my Tacoma last December (but I knew it would happen, I just needed it out of the garage to get the snow blower out). Snow was at the top of the tires and I went through it fine. But after parking, the packed snow in front and behind the tires will freeze and act like ice blocks trapping you. Fresh powder that isn't packed down is very easy to plow through in almost any vehicle. It isn't until it's compacted together that you get into trouble (packed either under the vehicle or around the tires). Even snow that's been sitting for a few hours compacts which can cause problems. Within 12 hours, snow that was 12 inches deep will usually compress to just 8 or 10 inches (if you live in snow country and measure it, you already know this). It's denser. I've watched (and helped to dig them out) a family in a Ford Expedition (who BTW never got stuck on their road with fresh deep snow) get stuck on an unplowed road in the spring because the snow was deeper than their clearance underneath the vehicle. They had no idea that the snow had compacted and hardened over time which left all 4 wheels in the air with no traction. Fresh powder, though, is a piece of cake (or should I say it's the frosting on the cake?).
 

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4wd

I've owned an '02, 06 and now '09 HL Limited and all of them were full time AWD. The Rav4 is one that I believe changed to FWD and AWD on demand.

Peter
 

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Now for my question, how does this compare to that vehicle in 4WD high?
If you do a search of this forum you'll turn up two or three threads regarding the Highlander and off-road use, with some extensive reviews by yours truly.....:D Suffice it to say, I have extensive off-road experience with a number of 4X4s, including my presently-owned Samurai, and I consider the Highlander to be as effective off-road as a true 4X4 in high-range. The one, single condition you don't want to get the Highlander in is what you indicated above, which is losing traction on two wheels. Twice I've been in situations where I was crossing a deep ditch in a tight turn, whereby one front wheel and one rear wheel lost contact with the ground, and I was immediately stopped in my tracks. Other than that specific circumstance the Highlander performs extremely well in deep sand, technical, rocky terrain, ice, and snow. I use it more than my Samurai now because it's so damn comfortable being in the Highlander. :thumbsup:
 

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Discussion Starter #16
If you do a search of this forum you'll turn up two or three threads regarding the Highlander and off-road use, with some extensive reviews by yours truly.....:D Suffice it to say, I have extensive off-road experience with a number of 4X4s, including my presently-owned Samurai, and I consider the Highlander to be as effective off-road as a true 4X4 in high-range. The one, single condition you don't want to get the Highlander in is what you indicated above, which is losing traction on two wheels. Twice I've been in situations where I was crossing a deep ditch in a tight turn, whereby one front wheel and one rear wheel lost contact with the ground, and I was immediately stopped in my tracks. Other than that specific circumstance the Highlander performs extremely well in deep sand, technical, rocky terrain, ice, and snow. I use it more than my Samurai now because it's so damn comfortable being in the Highlander. :thumbsup:
I did read that post and that is EXACTLY what I was wondering.... what were the two wheels that contacted the ground doing? Wouldn't the power be diverted to those wheels?
 

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I did read that post and that is EXACTLY what I was wondering.... what were the two wheels that contacted the ground doing? Wouldn't the power be diverted to those wheels?
If you mean did I look out the window to see if they were turning or not, no I didn't. Nevertheless, what happens is the Highlander does not shunt more power to the wheels still in contact with the ground and in a two-wheel contact situation mentioned above you're left with 50% power to the wheels. I was lucky in both the situations because I was driving up canyon, and was able to use gravity to back up successfully. If I'd been on totally flat terrain I would have been stuck and had to get out and shovel dirt and boards under the wheels to get her going again.

As you probably read in the other thread, when you take the Highlander off-road it's best if you shut off VSC/TRAC under some circumstances to improve traction/movement. Driving in sand or moving across ice are the best situations to shut it off, as it prevents the engine from dethrottling on you and getting you stuck. The situation where it's highly recommended to leave VSC/TRAC on is going down steep, especially slippery/loose hills or slopes. Engaging the Downhill Mode under those conditions provides phenomenal traction.

Thanks to that a**hole Wwest, I'm compelled to say: Turn off VSC/TRAC at your own risk. Please consult your owners manual which describes conditions recommended by Toyota for when to use the VSC/TRAC button Toyota has provided to Highlander owners. :D
 

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Discussion Starter #18
WWest... that's funny... does he work for Honda or something? His posts are plastered all over Edmunds, here and a few other places bashing the Highlander and trying to make his case on "F/AWD"....

Anyway, thanks. Even though this AWD system will not be as good as my Explorer in 4WD high I feel confident it can go to 99% of the locations I used my Explorer in 4-Hi. the only place i doubt it would work is deep sand in the OBX... but my explorer struggled through there even at 17 PSI in the tires! I actually got stuck but was able to get out after unloading my passengers and stomping on it....actually not quite, but it was fun crawling out of there. I took a lot of flack from my good friend driving his Sequoia behind me.
 

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Funny thing that wwest have never owned a Highlander but loves to bash it. I've driven my 2008 HL AWD through 3 Ohio winters and never had any issues. Needless to say that HL was never designed as an off road vehicle and it would be unrealistic to expect it to perform as real 4x4. I totally agree that there are better 4WD/AWD designs out there but for everyday city/suburbia use HL is more then adequate.
 

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WWest... that's funny... does he work for Honda or something? His posts are plastered all over Edmunds, here and a few other places bashing the Highlander and trying to make his case on "F/AWD"....
He has an obsession regarding Toyota and its AWD systems. Apparently he thinks Toyota has created a monster that is one step away from killing every owner, and he wants to inform the world about it. :facepalm: He's been banned from several forums for his :kookoo: antics, including TN. For those who don't already know, he threatened to sue me and TN for recommending to members to turn off VSC/TRAC under certain conditions, a button and a feature Toyota installed in the Highlander in the first place to help drivers! :facepalm: He never had a prayer of winning such a lawsuit, but what concerned me was having to spend megabucks defending myself if he had brought such a lawsuit, thus the reason I've stuck disclaimers in all the references to VSC/TRAC. Life could be so simple, and so less litigious, without so many nannies in the world....
 
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