Traction control operation

The only 4runner that will transfer power to both rear wheels when spinning is the 2wd version, which has a limited slip diff.

 

I wonder how effective it would be to engage A-TRAC. Or, can A-TRAC even be engaged in 2wd. I've never tried. I might have to try that on this winter's run.

 

Lol, placebo is strong I initially had a little bit of trouble figuring out the rear locker. Be aware, that even in 4lo, the button will not immediately engage the locker. Sometimes you need to roll forward a bit and turn the steering slightly until you hear a “click” from the back. Usually it’s not hard to get it to physically engage off road if you have poor traction, because usually both wheels wont move at the same speed once you give a little gas. Basically, unless everything aligns perfectly, the rotation between tires needs to be slightly different for it to “click” locked. Once locked, the dash indicator light will change from flashing to solid.

You also have to verify that it physically unlocks when you turn off the locker. I ended up driving a few miles down a paved highway with my locker still engaged, until I noticed the light was still flashing! When you push the button, listen for the click! Roll forward or backward and rock the wheel back and forth if you have to. But verify it’s off, often you can hear it click as it disengages. Then the locker indicator light will turn off.

 

I love that pic! If anyone is interested in visually seeing the difference between pressing the VSC button once, vs a press and hold, this picture is it!

Look carefully…The deep, dark, lurid, tokyo dorifto track belongs to @Thatbassguy. However, the limp attempt above belongs to yours truly. I had not yet been taught the dark arts of VSC disengagement.

 

I wanna say a-trac only works in 4wd IRC

 

4wd low only. My Tacoma had AUTO LSD that you could engage in 2wd for basically 2wd ATRAC and TRAC in 4wd would give you a weaker version of ATRAC but without throttle control.

I blame Toyota for calling the same thing a bunch of different names with different controls which causes confusion. It's like when someone lists an oil change as a mod.

 

Thank you I did not know this. Do you know if the diff has mechanical or viscous internals? I am continuing( ) to carefully read the owner's manual.

 

I want to say it’s mechanical, but not sure. I’m sure the manual will show the type of LSD it has.

 

This may be an ignorant or misguided question but I don’t care anymore in life what others think of me. Would it be better when off roading to by default leave VSC off or on? Meaning, when putting it in 4H turning VSC off at that time. Or would it depend on the terrain you are wheeling on?

This thread has been very enlightening. All the times I got pissed off at the 4Runner for preventing me having fun when trying to burn out… of course it was user error/stupidity.

 

VSC is automatically off in 4LO, FWIW.

 

Modern Toyotas have simulated LSD with the brakes (maybe not the 86) but the diff mechanicals are open. For the Tacoma, it started in 09 when theh added ATRAC and stuff but all 5th gen Runners are open diff except for the locking diff in the OR/Pro Bro/Early Trail levels and the locking diff is open until you lock it.

 

Mine gives out one clank when turning around on residential streets.

I'll edit this when i find all the info in the manual. I imagine a viscous diff needs wheel speed to load up and don't work well at low speed. I havent driven anything with a (nonopen) diff.

edit. Read the manual.

 

I usually turn it off for off-roading, but I could see it being helpful in some situations. I generally don't want it on for mud, in case I need to spin the tires to clear them (or just for fun).

 

i’ve never had a limited slip. Is this what they do? You can hear them open up when turning?

 

I believe my Supra had a limited slip. I don't remember ever hearing it.

 

I was half joking and I'm pretty new. But conceptually the LSD engages and limits the ratio of wheelspin between the two wheels. If you make a tight turn (like a uturn or multiple sharp turns in a parking lot) you could have this situation with the outside wheel turning more times to cover the larger outer turn radius, and the diff might lock down and drive the inside wheel in turn. That clank could be it or something else (including something bolted to the driveline), it's barely audible at 4mph.

ALSO the whole point of the LSD is it's more manageable while turning, and perhaps braking, than a locked diff. Because when the diff locks and drives that inside wheel, that wheel is pointing outside of the arc the front wheels are making. Power understeer. So I wouldn't be surprised if the 4runner lsd stays open during turning in circles with no additional wheelspin.

 

Yeah that makes sense.

Your post reminded me. I put an LSD in my 2001 Eclipse way back when. It did something like limit the difference to 60/40 or something between the two wheels when turning. The interesting thing that it did is when you were in a low speed turn, like in a parking lot or pulling a u-turn is that when you let go of the steering wheel and let the wheel spin free in your hand until it finds straight again, it sometimes wouldnt. If you had the wheel turned the right amount and you were giving the right amount of gas like maybe if you you were matching the 60/40 - it would just keep turning. Something to do with front wheel drive so the LSD was also on the turning wheels.

Several times I would let go of the wheel, it would not straighten at all and instead and keep turning. I'd then need to quickly and violently recover lest I hot a car or curb.

 

@Thacrow that sounds like it could be power oversteer characteristic, which happens on fwd cars with diffs. Front axle exerts lateral force on rear wheels because the trajectory don't match. My understanding.

 

If you have really good tires FWD cars can pull you through turns and it is pretty cool.

But the weird thing I was talking about happened at low speeds when the radius of the turn about matched the power distribution to the tires.

 

Yeah I have been thinking about that since I posted. I'm not sure my prior post is very accurate. I wonder if the inner wheel pulls/holds the steering while the diff engages at low speed. (The power oversteer condition is from the power transfer to the outer wheel as the inner wheel breaks loose, compare with open diff where you understeer whilst the inner wheel spins (not at low speed))

edit this must be why toyota has a mode for AUTO LSD

 

I think it depends on your objective. Has your holiday trip turned into a nail biter due to weather and you’re just trying to get from point A to point B? Or are you just out having fun playing with your truck?

I would personally prefer zero input from the various assistance systems. Like driving a pickup before any of these systems existed. And then turning the systems on on an as needed basis (ie. oK NOW I’m stuck).

That said… traction control has saved my ass on the highway in patchy slippery conditions more than once. So I don’t complain much.

 

Since Toyota owns Torsen, I’d bet the LSD in the 2WD models is mechanical .

 

No info about the mechanical or operating characteristics of the differential in the owner's manual. The only mention of limited slip differential is in the specs published by T. I was aware of this, but still wasn't sure if it was the diff is actually lsd or it's the traction control setup.

also there is an advisory from T in there about auto lsd. So the vsc off icon illuminating alongside auto lsd is real

 

Open diff.

 

According to the brochure, the two-wheel drive 4Runners come with an automatic limited slip differential.

I'm not sure if that means it is electronic.

 

It just means it's fake from the brakes. Toyota did this in 09 in the Tacoma to save on costs and not pretty much all of their vehicles use this except for maybe the Zupra and the 86. It wasn't even a Torsen when they did have it.

 

So, it's electronic, as I mentioned. Sounds like 2 wheel A-TRAC, basically.

 

Yeah but not a mechanical like a Torsen or Truetrac.

 

Right. I don't know how they can even call it a limited slip differential when it's actually the brakes that are limiting the slip. Seems misleading.

 

ATRAC, ALSD, TRAC, MTS, Crawl control...it's all just traction control. CC I get since it's a speed function but the rest should just be TRAC and maybe TRAC Control for the Mall Terrain Select.