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Toyota 4WD systems explained



  • wwestwwest Posts: 10,706
    :confuse: :cry: :surprise:
  • guchguch Posts: 12
    I need help with understanding sequoia system.
    I am planning on buying this truck for my wife. Since it is a RWD truck I worry about her driving it on wet roads and in snow. Switching to 4WD seems to eat a lot more gas so it seems like a waste to drive in 4WD in just little rain or snow. How is Sequoia's traction control and vehicle stability control going to do in these conditions? Dealer says it does greatith VSC alone withput need to turn on 4WD.
    My other option is to get Lexus GX 470 or 460 when it comes out , these are full time AWD.

    Thank you for your advise and help
  • Do any current SUV's have a selectable 4WD/AWD mode, it seems to be more fuel efficient while most of your driving is generally 2WD. Thanks
  • wwestwwest Posts: 10,706
    In reality RWD vehicles are a lot more safe in adverse roadbed conditions than their FWD and/or F/awd "brotheren". Even if your wife should leadfoot it a bit inappropreately the RWD vehicle will still have available traction at the front with which to sustain or assume directional control.

    Whereas with FWD or F/awd absent Trac she would be in rather serious jepordy. That's why owners are complaining so LOUDLY about the aggressiveness of TC in their FWD and F/awd vehicles. Absent TC's aggressiveness upon detection of even the slightest level of wheelspin/slip there would undoubtedly be a lot more accidents attributed to FWD and F/awd vehicles.

    Just think of TC as the inverse equivalent of ABS, it's there to save your life.
  • I have a 2000 LC (love it, had since new) and have run dedicated snows on it in the winter. I have DMZ2 Bridgestone and hit something in the road that trashed one tire. They have low miles (<5k). I cannot find a 275-70 16 DMZ2 to replace it as they have not made them now for several years.

    NTB/Sullivan Tire are both telling me I need to replace all 4 tires or I will trash the AWD system as different snow (even the DMZ3) will have different tread pattern = differnt rolling resistance. They claim the AWD system will see slippage all the time instead of temporary (as it was designed for) and wear out the system.

    They claim they will not even mount a single snow of different tread type. Even if I replace 2 (same axle). My question is, is this overkill or not? I have 120K on my LC and would like to keep it and do not want to create problems, but my engineering mind says if I mount two of the same on each axle, even different treads (but close) I will be fine.

    What would you do? Throw out 3 perfectly good tires and drop $600 to replace? Replace 2? or 1?

    Thank you
  • wwestwwest Posts: 10,706
    I NEVER rotate the spare so it is always available in the kind of instance you have.

    I would NEVER replace only one tire on an AWD vehicle, 2 at the minimum.
  • Replacing 2 on the same axle is probably alright then?
  • wwestwwest Posts: 10,706
    Same tire size, and only 5,000 miles on the others, I would say yes.
  • How does not rotating the spare help the situation where one tire is destroyed? By rotating the spare wouldn't it be approximately the same treadwear as the remaining 3 tires? Then a new tire can be purchased as the spare. Once the primary 4 need replacement reintroduce the spare to rotation.
  • steverstever Posts: 52,683
    You can shave a tire to match the circumference of the other three, so that would be an option if you choose not to put the spare in the rotation, and there's a significant difference between the spare and the other three remaining tires. It may take a bit of scouting around to find a tire shop capable of shaving the tire.

    I have a flat on my Subaru right now and I'm hoping that it's an easy fix, since my spare is a space-saver.

    Tirerack has a page about replacing tires on AWD and 4WD vehicles. They recommend rotating the spare on 4WD/AWD vehicles.
  • That is where i was going. Shaving the new snow to be the same size. National Tire and Battery, Sullivans, all the major chains I have spoken with said they will not even mount a snow with a different tread pattern (never mind slightly different diameter that I would fix with shaving). Not even if I put 2 on the same axle that are different from other axle. So right now I am proabaly going to buy 4 new snows (1 free on purchase of 4 at most places right now) as I was going to buy 2 for the same axle and for the price of one more ($120) I have no worries.

    I think it is a scam. how much rolling resistance difference can there by between redesigned snows from the same mfg? If that is really enough to quickly wear out a differential?
  • steverstever Posts: 52,683
    That's probably the best course. Tire Rack says "Mixing tire brands, tread designs and tread depths may cause components in the vehicle's driveline to fail" but they really don't go in depth about tread designs too much.

    I posted some tire sales over in Auto Parts Bargains and Coupons not long ago, but some may have expired. But tires always seem to be on sale. 4 for 3 is a better deal than the $50 or $70 off a set sale too.
  • Will there be any problems with handling, transmission, ABS system etc because I went from a tire size of 275/65/18 to a 265/70/18 on my 09 Sequoia? I realize my speedometer will be off by 1 mph. The tire dealer said no problem but now I'm worried.
  • wwestwwest Posts: 10,706
    TireRack is in the business of selling tires.

    So their sales/marketing spiel/advice will undoubtedly be slanted toward up-selling.

    These days with many AWD systems that have some sort of "soft" or "reactive" mechanical coupling (TC excluded) you really do need to be a bit more carefull that all four tires have roughly equal, within a fairly tight tolerance, circumference.

    On the other hand if your AWD happens not to have one the system designated above, say you have a Highlander or Sienna, the only downside will be early, sometimes, activation of ABS or TC.

    I rather doubt that early diff'l failure would be a result as many RV/MH owners use remcotowing(.com) technique to "drop" one front halfshaft out of "drive" so the vehicle can be towed 4-down.
  • wwestwwest Posts: 10,706
    You have no cause for worry.
  • steverstever Posts: 52,683
    I guess I'm sensitive to the circumference issue since I have a Subaru. Remco says I'd have to trailer it behind an RV.

    Actually they say that for newer Sequoias too. The Highlander is ok, with their kit.

    Interesting link, thanks.
  • wwestwwest Posts: 10,706
    Yes, except for TC intervention to prevent a wheelspin/slip the HIghlander was, is, and remains a ONE-WHEEL drive system. In TOAD mode the HL's TC will never activate so allowing one wheel to "slip" via the Remco system eliminates any question of driveline stress.

    I just went to to confirm this and it appears that Remco may have misinformed you. The Sequoia 2WD (RWD) model can be trailered as long as the rear wheels are off the ground or Remco's drive shaft disconnect is used.

    The Sequoia AWD/4WD/4X4 model can be towed 4-down for the same reason the HL can. In AWD mode, "full time" 4WD (H4F) it has three simple fully open diff'ls, front, center, and rear, just like the HL, Sienna, and the RX330 a ONE-WHEEL drive system absent TC activation.

    Put the system in H4F mode, "Open" one of the 4 halfshafts and GO...

    For some reason I had thought that the Sequoia had a more sophisticaded AWD system, center VC or Torsen, but apparently not.
  • My 2002 Sequoia is eight years old as it was purchased in late 2001. The transfer case stopped working. I only have 76K on it and we drive the beaches of New England only five months of the year. Some rare use in the winter with snow. A used transfer case was used as a replacement by the dealer to keep the cost down. (nearly $1,300) I must admit I am disappointed. I have had a Montero and a Ford Explorer previously, each lasted ten years with similar use and no 4WD problems. Anyone else had problems.?
  • cyd3cyd3 Posts: 4
    hi. so thankful to find this forum - this is my first post! i drive an 04 sequoia ltd. 4WD. we got about 2 1/2 feet of snow here last night. i shoveled out my driveway and got stuck trying to get out. neighbors had to rescue me. got out, got stuck again. rescued again - love good neighbors. all agreed my truck should have been plowing thru the snow. i don't believe i had the 4wd set correctly and can't determine the proper setting from the vague description in my manual.

    i had the truck in 4H. the 4 green tires were lit and the orange button in the center of the 4 tires was blinking. from what i can gather from my manual, the orange button should be solid which indicates the VSC system is OFF which is how it should be when driving on slippery roads/when you're stuck. i could not get the orange light to go solid. what am i doing wrong? any advice would be extremely appreciated. when i got home last night, i got stuck again coming into my driveway so i just left it there! :confuse:
  • ronnronn Posts: 398
    Hello out there,
    I live in Roanoke, Va and we have just seen one of the largest snow storms in years here, with up to 20 inches. This is my first snow with the Highlander, and I must tell you that it did beautifully in the 16 inches at my home and on the roads nearby.
    I have new HT's on my 2008 Highlander Limited, and they did great !! I had to take a friend to work and pick up at 11:00 pm when the weather was at it's worst, and the Highlander was great. Did not slide or spin on the very deep snow covered roads. I am so thankful that I feel secure with this vehicle, and I know it will get me through rough weather now. To all of you thinking about a Highlander, I highly respect this vehicle, and the HT tires. It is realiable and fun to drive, and it looks great !
  • With my 2002 Sequoia, when the 4WD button is pushed the four green lights come on and the reddish center button blinks. When the 4WD engages the red light turns off. See my post above about the transfer case. When mine stopped working the red light kept blinking and even when the 4WD button was pushed again, which usually turns off all the lights. The dealer told me that the transfer case was not communicating with the front differential and that the transfer case needed replacing. They said that trying to repair it could be very time consuming and probably more expensive than a part replacement. If the big snow storm had not been predicted for Boston I would have taken my SUV to a 4WD specialist for a second opinion, but as the storm was coming, I did the quick fix and had them replace my transfer case with a used one and it is now working fine

    Does your blinking red light turn off when you hit the 4WD button to turn off the system?
  • wwestwwest Posts: 10,706
    "..we drive the beaches..."

    Sandy beaches usually/often involve highly tractive surfaces so use of actual 4WD mode, locked center diff'l, is not appropreate unless/except to get unstuck. So using 4WD "pre-emptively" could be the siurce of your failure.
  • wwestwwest Posts: 10,706
    When you first tried to get into 4WD the spline clutch, dog-clutch, moved part-way into the locked position and became stuck there, "mid-point" between locked and unlocked.

    Should have been a simple/quick fix so be sure and take possession of the broken part or the dealer will be making double profits.
  • cyd3cyd3 Posts: 4
    blackdog4 - thanks for your reply. the blinking red light stays on even when the green tire lights are off.

    i've only used the 4wd system a few times - like literally 4-5 - since i've owned the truck - which i bought new. i can't imagine how something could be broken on it. i think i'm missing something on how to turn it on and off.

    the steps i took: 1) put truck in neutral 2) put into 4H 3) turned on 4wd button 4) turned 4 tire button on (next to 4wd button)

    this gave me the 4 green tires and red flashing light and when i drove there was a very high pitched noise coming from engine.

    i don't know that i took the right steps or did the right steps but maybe in the wrong order? as i said, my manual really stinks.

    thanks again
  • I never need to use the 4WD low on the beach. I only hit the 4WD button on the dash. In this setting you can even drive at highway speeds safely. It was my impression that this does not lock the center differential which would be unsafe for general driving.
  • cyd3 Your Sequoia is doing exactly what mine was doing and the dealers diagnosis is in a post above. The dealship moved into a huge, new, high tech, very expensive building at the bottom of the economic slump and as I said I would have prefered a second opinion. However, something was definitely wrong with the 4WD system as I have used it frequently for the eight years that I have owned it without problems.
  • cyd3cyd3 Posts: 4
    blackdog4 - since i can't get the light to stop flashing - even after turning off the car and restarting - i'm wondering if it's safe to drive. am i going to damage the vehicle by driving it this way?
  • cyd3-I drove for three days before I could get it into the dealer. Everything seemed fine except that I could not get into 4WD. I talked with a senior technician in detail before coming in and they did not advise me not to drive my SUV.

    Please let me know what you find out about your problem.
  • cyd3cyd3 Posts: 4
    blackdog4 - i will let you know what i find out. thanks so much.
  • I have a 2002 sequioa and it will never engage into 4wd H while in drive and on the move . At very low speeds I can put the vehicle into N and push the button for the 4x4 and it will engage sometimes. Or I can come to a complete stop, put the vehicle into N and get it to engage into 4x4 about 50 percent of the time and the other 50 percent of the time, I have to drive forward, drive backwards, and do this several times before it will engage. I can drive for miles without the system engaging if I dont stop the vehicle and go through the process of shifting from gear to gear and driving several feet in each direction. The same thing happens when I want to disengage.

    The other issue is that when I shift into 4x4 L and put the vehicle into L gear, the VSC is not turned off automatically. Should it be?

    I took it to a Toy Dealer. They tried to tell me that one of my tires was slightly worn more than the others and that was possibly the cause. I did not believe that and did not buy new tires. I also went on a drive with a Toyota Tech, he said that it was taking too much for the 4wd to engage, but eventually went with the tires possibly being to blame. I took it to another toy Dealer, they said nothing about the tires but said that the 4wd should preferably not be engaged while the vehicle is in D and said that it works fine while in N, they claim that they could not find anything wrong but they also had trouble getting it to engage while moving and in drive. I have taken it to the dealer 3 different times now for this problem and my extended warranty will expire in another 5,000 miles.

    Any ideas out there or is this completely normal with Sequoias? :confuse: maybe :lemon:
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