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Toyota 4WD systems explained

2487 messages,  Last post on Apr 28, 2012 at 12:48 PM

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What is this discussion about? Toyota Sequoia, Toyota Highlander, Toyota 4Runner, Toyota Land Cruiser, Toyota RAV4, Toyota Tacoma, Truck, SUV

Messages Page 247 of 250

#2454 of 2487 Re: Toyota 4WD in recently models [vavavavolvo] by wwest

Dec 27, 2010 (10:48 am)

Replying to: vavavavolvo (Dec 26, 2010 1:57 pm)
"..you cannot disengage traction control.."
 
I strongly suspect that's because TC is automatically disabled with a TPMS warning light on.
 
Early TPMS's used the ABS "tone wheel" to judge that a tire was under inflated. TC also relies on those same ABS tone wheels to detect the onset of wheelspin/slip. The TPMS fault indicates that use of the tone wheel for TC functionality might be "suspect" so I doubt it would be, remain, active.
 
Check your owners manual.
 
But ABS might also be disabled for the same reason. If so it would not be a good idea to drive in adverse conditions with a TPMS fault indication.

#2455 of 2487 Re: Toyota 4WD in recently models [mdhutton] by wwest

Dec 27, 2010 (11:17 am)

Replying to: mdhutton (Dec 26, 2010 5:12 pm)
For all practical purposes I do own a 2008 HL 4WD....
 
Mine just happens to be a 2001 RX300 "F/awd". With the advent of the use of TC starting in '01 the TC remains in the "mix" but with the viscous fluid reformulated to forever remain "flaccid".
 
So I have the very same drive train implementation as you.
 
The first thing I did was add wheel spacers all around and 17x8 wheels with the appropriate +1 summer use only tires, Brdigestone Turanzas, to be exact. The spacers not only allowed for wider tires, more roadbed contact area and wider "stance", but also room between the suspension and tire in the rear such that I could make use of tire chains in the rear initially and only add the front chains at times of real need.
 
I would NOT advise disabling TC as a rule of thumb, not, NEVER, on a FWD or F/awd vehicle. TC is a totally REACTIVE feature, only activating AFTER the fact, after wheelspin/slip has already become an issue to be dealt with, URGENTLY dealt with.
 
Engage the snow button, YES, indeed.
 
Tires..Mixed bag.
 
The following is my personal opinion ONLY.
 
I am of the firm belief that the clear majority of the time my summer tires provide superior traction, above ANY wintertime specialty tire. The "clear" majority being dry, wet, icy, or packed snow roadbeds. Specialty tires have less surface CSA, less traction on a "solid" surface roadbed. Winter tires are only advantagous on "soft" roadbed surfaces wherein that tread blocks have something to "dig" into.
 
But my advice to you is to buy the best all-season tires you can find and trade up to a R/awd or even a RWD vehicle ASAP. I had expected the new 2011 HL to have adopted the Venza, Sienna, and RX350's new F/awd system but apparently not. This new F/awd system could be easily modified to a PART-TIME 4WD system using a manual switch to over-ride, temproarily close the circuit to the rear clutch. Obviously that switch should ONLY be used in KNOWN adverse conditions, SLIPPERY roadbeds.

#2456 of 2487 Re: Toyota 4WD in recently models [vavavavolvo] by wwest

Dec 27, 2010 (12:33 pm)

Replying to: vavavavolvo (Dec 26, 2010 1:57 pm)
What is the advantage, cost, etc, of purchasing a set of dedicated wintertime wheels and TPMS sensors vs just simply having a tire shop swap tires twice a year..?

#2457 of 2487 Re: Toyota 4WD in recently models [wwest] by vavavavolvo

Jan 07, 2011 (2:04 pm)

Replying to: wwest (Dec 27, 2010 12:33 pm)
Reasonable question. The price for four BlizzaK Tires mounted on new steel wheels is about $650, and the TPMS monitors are $116 for a set of four (Honda sensors are inexpensive compared to many other brands for some reason). So it is about $775 for the whole shooting match including sensors.
 
The Blizzak's alone are $430. Mounting and balancing around here is about $20 per tire.
 
So here are my options and the prices:
 
Dedicated tires/rims and no sensors: $650 (one time charge-I change these myself) Disadvantage- either cannot turn traction control off, or --as you suggested--traction control is always off if system sees no TPMS sensors. I think that ABS still works in this vehicle under these conditions.
 
Dedicated tires/rims with sensors: $775 plus $80 twice a year for the Honda guys to reinitialize car's computer each time for the alternate set of sensors (winter vs summer tires).
 
Tire shop swaps tires twice a year: $430 plus $80 twice a year (this time the same $80 is spent on the tire changeover instead of the sensor re-programming)
I guess I wasn't considering this because it is so convenient for me to just switch out my own tires in the driveway with a floor jack vs taking it to a shop and waiting. Also, my nice rims don't get mucked up in the winter.
 
Thanks for the comment about the possibility that traction control is already disabled with TPMS light on...I never thought of that and will research this more and comment back. Just read the post today.
 
Many thanks.

#2458 of 2487 Re: Toyota 4WD in recently models [vavavavolvo] by misaak

Jan 07, 2011 (2:19 pm)

Replying to: vavavavolvo (Jan 07, 2011 2:04 pm)
Where do you buy the tires for $430 for Blizzaks?

#2459 of 2487 Re: Toyota 4WD in recently models [wwest] by daniell

Jan 07, 2011 (2:46 pm)

Replying to: wwest (Dec 27, 2010 12:33 pm)
1) You can get cheaper winter beater wheels.
2) You can get -1 or -2 size wheels. With those, you will need tires with taller sidewall which give better traction in snow and slush. Those are cheaper too, and the difference is significant for most brands.
3) I am not sure how much it costs to swap tires, say $50-$80. That's $100-$160 per year. Over a few years it adds up. If you keep your vehicle for a long time, it's proably cheaper to get the second set of wheels. Swapping wheels is something I can do myself in my garage, it takes me about 40-50 min., probably less than driving to a tire place (with 4 dirty tires in the trunk), and have them balance and swap the tires.
4) All that repeated swapping can't be good for tires.
Etc.

#2460 of 2487 Re: Toyota 4WD in recently models [wwest] by oldad1

Feb 10, 2011 (12:22 pm)

Replying to: wwest (Dec 27, 2010 11:17 am)
"F/awd system could be easily modified"
 
My 09 HL one wheel drive is nearly useless in the snow and I am wondering how one would go about modifying it as you described using a switch to over-ride the the clutch.
 
In your opinion would this help substantially or is it just wishful thinking?
 
I am pretty handy with a tool and would seriously entertain this idea, realizing of course (hoping really) that it would be like locking in a tranfer case.

#2461 of 2487 Re: Toyota 4WD in recently models [oldad1] by wwest

Feb 11, 2011 (11:15 am)

Replying to: oldad1 (Feb 10, 2011 12:22 pm)
Sorry, but I was referring to the NEW F/awd system now used in the Sienna, Venza, and RX350. Those have an electromagnetic clutch just forward of the rear diff'l that is used to dynamically apportion engine torque to the rear drive.
 
In those a simple switch might be used to fully engage the rear clutch provided that there is absolute certainty of a non-tractive, slippery surface.
 
Basically a "part-time" 4WD system.

#2462 of 2487 Re: Sequoia, Land Cruiser and 4Runner [cliffy1] by donovancook

Jun 24, 2011 (9:30 pm)

Replying to: cliffy1 (May 16, 2001 3:59 pm)
2003 Toyota Sequoia 4X4
 
Is there a way to override the TRACS and VSC system? I was heading up a muddy slope and it felt like the rev limiter kicked in and I couldn’t power up the rest of the way – it felt like it was trying to get traction and slowing the revs of the motor to do so.
 
Am I able to flash my ECU, pull a fuse, or snip a wire? Did I just buy a soccer mom taxi?
 
Thank you in advance for any insight or explanation anyone can extend.
 

#2463 of 2487 Re: Sequoia, Land Cruiser and 4Runner [donovancook] by wwest

Jun 25, 2011 (9:49 am)

Replying to: donovancook (Jun 24, 2011 9:30 pm)
In a true 4X4 if you lock the center "diff'l" that automatically disables TC and VSC. Sounds like in the conditions you had you needed to be in "locked" 4X4 mode.

Messages Page 247 of 250

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