I have read conflicting information regarding the Highlander's AWD operation. Some info says it's a full-time AWD, other says the V-6 operates like the Hybrid's system - i.e. "on-demand" AWD.
I don't like "slip-grip" systems very much, having been spoiled by our various Subarus. However, Subaru has no models with the interior room of a Highlander, so we're thinking about going with the Toyota.
My issue is that the SUV is used often in the Canadian Rockies on very challenging winter roads to access trailheads. Our Subaru Forester, on Blizzaks, has just enough to get us in and out, and we've seen RAV-4's struggle, so if the Highlander's system is similar to the RAV's, I'm hesitant to go that route.
So, anyone know for real how the Highlander's system operates?
Nice that it's a full time AWD system, sucks that none of the diffs are LSD. Looks like Toyota relies on the traction control system to direct torque. I'd much prefer at least rear LSD, allowing three wheel AWD operation.
Maybe I'll wait until a bad winter day arrives and test drive one then...
Nice that it's a full time AWD system, sucks that none of the diffs are LSD. Looks like Toyota relies on the traction control system to direct torque. I'd much prefer at least rear LSD, allowing three wheel AWD operation.
Maybe I'll wait until a bad winter day arrives and test drive one then...
Like Moose suggested, we've got a number links to past threads located in the same sticky that summerwind mentioned, which cover the Highlander in snow, sand, mud, and other off-road or foul weather conditions. My experience is that it has always performed very well, but best of all when you turn off the VSC/TRAC systems as suggested in your owners manual.
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2008 Highlander Base 4WD
2002 Avalon XL
1987 Suzuki Samurai 4X4 - Treading where no Jeep can follow....
Disturbing number of posters driving in winter conditions without winter tires. I take it few Americans, even in the snow belt, use dedicated winter tires?
Most of us don't tend to have much in the way of constant ice/snow on the ground. Between storms we're driving on pavement which wears them down faster. Or in my case, you drive down the hill and you're in an elevation that only gets rain (or they plow the roads and then you're just dealing with patches on the road while most of it is dry). So it doesn't make sense in a lot of cases. On top of that, dedicated winter tires like the blizzaks and such don't perform as well in deep snow. They've got a soft rubber compound to deal with ice, but drive around in 1-foot deep slush all the time and you'll see they just don't do as well as an AT tire.
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Originally Posted by Chalkie
That's why he be a moderator and we be the peons... cleverness!
I live in Ohio and went through 4 winters without any issues on OEM Bridgestone Duelers. They should last for another season. Never felt I'd need winter tires.
Ah. We have reasonable urban driving conditions, but thanks to cold temps (well below freezing) winter tires work much better as they stay soft. All-seasons freeze hard like a hockey puck.
I drive on poorly maintained mountain roads that can have a great deal of snow, so a dedicated snow tire is an absolute must. The older WS-50 Blizzaks are horded by Subaru-owning back-country winter enthusiasts as they work well in both deeper snow and ice. For urban driving (plowed, but icy) the newer WS60/70 tires are better as they have better ice performance.
Nice that it's a full time AWD system, sucks that none of the diffs are LSD. Looks like Toyota relies on the traction control system to direct torque. I'd much prefer at least rear LSD, allowing three wheel AWD operation.
Maybe I'll wait until a bad winter day arrives and test drive one then...
My impression has always been that (in general), traction control based systems are more than adequate for most on-road inclement weather situations. For more heavy duty off-road or deep snow situations, a more robust differential will probably perform better. They tend to react quicker, transfer more power and operate at higher speeds. Problem is, they also cost a lot more and have more costly maintenance, so many vehicles don't offer them any more. Those that do often only have them in the center differential and use traction control to send power left-to-right. I believe some current systems, like Jeep Quadra Drive, still have robust differentials in all three locations, allowing much better peformance in off-road and deep snow situations. Of course, in practice, there may be little difference among them depending on your particular use. So, finding accounts from someone who has similar use might be the best information you can find. Plus, many manufacturers are intentionally vague about their AWD systems, so it can be hard to tell what the hardware really is.
As a newbie owner of an '08 HL Sport, why would the operator turn off the VSC/TRAC systems. Are they not there to aid in traction in the winter ? Sorry if it's a silly question, but had to ask. Winter is not far away up here and this could be quite important.
As a newbie owner of an '08 HL Sport, why would the operator turn off the VSC/TRAC systems. Are they not there to aid in traction in the winter ? Sorry if it's a silly question, but had to ask. Winter is not far away up here and this could be quite important.
Gary
Gary, take a look at the links posted up in the Common Problems & Solutions sticky that refer to driving in snow, ice, sand, etc., which will offer some in-depth explanations. The short of it is that with VSC/TRAC engaged the engine detects the slippage and dethrottles the engine which inhibits forward motion, but if you turn off VSC/TRAC the engine will not dethrottle while the AWD system handles slippage and you can move with confidence. I would never turn off VSC/TRAC on open roads and high speed driving, but rather as the owners manual states at very low speed conditions it can become advisable to turn it off in order to improve traction.
Here's a photo, Gary, of a section of dirt road I was driving over that was solid ice laying on top of the dirt and covered with snow, and although it doesn't look like it it's actually about a 6% to 7% grade. Driving under normal conditions with VSC/TRAC on I immediately bogged down and stopped at the beginning of that bend with all wheels spinning. I backed up, engaged the Snow button, and proceeded forward and only made about six more feet up the hill before the engine dethrottled and I ground to a halt. I backed up again, turned off the Snow button and turned off VSC/TRAC, and then proceeded up the hill with an estimated 15% slippage of the wheels, but the overall movement was confident with no sliding at all. This was done with the OEM Bridgestone Duelers (laughable, I know, in off road conditions) and when I was going through the learning process of how to get the most out of my Highlander in off-road conditions, and it's a good example of what turning off VSC/TRAC can do for you. Again, consult your owners manual for additional information.
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2008 Highlander Base 4WD
2002 Avalon XL
1987 Suzuki Samurai 4X4 - Treading where no Jeep can follow....
The Following User Says Thank You to TrailDust For This Useful Post:
Thank you, awesome info TrailDust .... but, does turning off these systems effect still operating as an AWD - other than the traction control, etc.? As an example, my wife has an '06 330xi and you can disable the DTC system and in effect run as rear wheel drive vs all-wheel drive.
Thank you, awesome info TrailDust .... but, does turning off these systems effect still operating as an AWD - other than the traction control, etc.? As an example, my wife has an '06 330xi and you can disable the DTC system and in effect run as rear wheel drive vs all-wheel drive.
Gary
Nope, no affect on AWD...all four wheels receive power and keep turning. The primary benefit is the engine is not allowed to dethrottle, and as some of our members have found out that's a showstopper particularly in sand. Personally, I recommend turning off VSC/TRAC ahead of time if you're driving off-road and are about to head into sand, mud, ice, or snow, or if you anticipate doing so. I've never been stuck in my Highlander, and that's with my suckie Duelers too. After Tahoe, I've got my eyes focused on a set of Yokohama Geolanders which, relative to my Duelers, blow them away in all performance characteristics.
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2008 Highlander Base 4WD
2002 Avalon XL
1987 Suzuki Samurai 4X4 - Treading where no Jeep can follow....
Nope, no affect on AWD...all four wheels receive power and keep turning. The primary benefit is the engine is not allowed to dethrottle, and as some of our members have found out that's a showstopper particularly in sand. Personally, I recommend turning off VSC/TRAC ahead of time if you're driving off-road and are about to head into sand, mud, ice, or snow, or if you anticipate doing so. I've never been stuck in my Highlander, and that's with my suckie Duelers too. After Tahoe, I've got my eyes focused on a set of Yokohama Geolanders which, relative to my Duelers, blow them away in all performance characteristics.
The Highlander system must be different than I thought. In a typical system with three open differentials, it is the traction control modulation of the braking system that allows power to be shifted from a slipping wheel to a non-slipping wheel. There is inherently a significant loss of power in this system, but you can effectively send at least a small amount of power to the 4th wheel even if the other 3 lose traction and are being modulated. In such a system, the advantage of turning off traction control is specifically to send all the power to a single wheel, even though it is slipping. It sounds silly offhand, but the idea is that you can sometimes "rock" a vehicle from being stuck by alternately going forward and reverse. You can also allow that one wheel to spin at a higher speed, which may also be a benefit in specific situations. Outside of that, disabling the traction control system would tend to have an adverse effect on traction in this type of AWD system.
Now, it may well be that the Highlander does have one or more differentials that limit slip by a means other than traction control. This could be a viscous coupling or something more mechanically advanced. These systems tend to allow much more power to be transferred from a slipping wheel to one that is not slipping and also would not necessarily require any de-throttling. If this is the case, disabling the traction control system could have additional benefits in certain situations, depending on how the traction control system is integrated.
Well, that's my understanding of it, anyway! Perhaps an expert while chime in to clarify if I got something backward.
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