I know active trac will brake a wheel that is spinning and try to get it to grip on ground but does it send power to the wheels that are gripping?

 

Yes. That's the other half of how that system works.

 

So basically its a computrized locker , i have had times when i was on 2 wheels and the wheels that where in the air at times would spin and others would not? tell me your expierences

 

To an extent. If you had front and rear lockers and 3 wheels slipped, you would get 100% of the engine power to the one that still had traction. I've seen the numbers on the A-TRAC, but I forget exactly. It's something like up to 70% in the rear and 40% to the front. Not nearly as efficient as true lockers, but I've been impressed with what mine has done and by watching another. That additional 40% pulling power up front is what no one else has with a pre-'01 that has open an open front diff.

I haven't been able to witness what they do when 2 tires are in the air. It's tough driving and looking at all 4 tires, you know? I, like you are a little curious about that now. However, there has been someone else (StarNRG--can't remember if he's on this board or 4x4 Wire only) with an '02 that was in the same scenario and the 2 with traction were indeed moving and got out of whatever he was on. He said he was going to post a video of him re-doing this for someone, but has yet to do that.

Hmmm. Were you on a pretty big incline or what exactly?

 

What is active trac and how do I know if my truck has it?

 

You don't have it. It is on '01+ 4Runners and other Toyota SUVs and cars. The Tacomas still have the option of the rear locker which was replaced on the Runners with this stuff.

It does what we've stated above: brakes the slipping wheels and (should!) directs the power to the ones that still have traction.

 

Check your owner's manual. The first truck I saw it on was my '00 Land Cruiser, then my '01 Sequoia. What's interesting about TRAC is that it sends the torque from the slipping wheel only to the other wheel on the same axle, from what I've read. The potential (and realized) downside is pulling into traffic on a wet road because along with active trac (TRAC) control comes reduced engine power output when you may need it most. I hope it's been refined for '03, but it was possible to run out of torque from TRAC/ECU engine power management (retard) when a locker ('99 and earlier Land Cruiser) would've pulled through.

 

VSC cuts power, not A-TRAC. This is solved by locking the center diff which also disables VSC.

Okay, I need a breather now. Someone else step in.

 

Both VSC and TRAC may cut engine power, as witnessed by separate dash indicator lights and tones when either is engaged on an '00 Land Cruiser. It takes a little more work to get the VSC light and tone, though!

 

Well, since I don't have it, I'm out...

 

I found this thread doing a search.

Try doing donuts in sand or snow with the center diff locked and the computer will kill your throttle, so my analysis is Darren is wrong.

Active TRAC is basically an electronic limited slip differential. However, it doesn't help you if you aren't moving and you have a wheel in the air for more than a moment. The reason is, the computer applies the brakes in short pulses, and if the opposite tire isn't able to grip and move you forward during a pulse, when the pulse is over, you'll be right back where you started (not moving). It would be sweet if Toyota could re-program the chip to allow it to keep the brake appied for increasingly longer pulse durations until it sensed acheived traction.

 

Bring back an old enough topic there, Mike?!

Try getting stuck in any situation (like snow) where only 2 wheels will spin and the system doesn't work at all. You'll still have all the RPM's you can throw at it. Sounds like you've experienced something different than what I ever have. Donuts are different than the above scenario, but my throttle remains affected only by VSC. TRAC has NEVER inhibited this.

By the way, you can email me that slide show we talked about awhile back whenever you get around to it. Thanks!

 

Hmmm. I know what you're talking about, Darren, as far as the spinnig wheels go. I experience that, too.

Maybe it's when you're on a surface where there's some traction, but not a lot, the computer limits the throttle. (As opposed to what you're describing, which I think is where there's no traction at all.) I exeperinced that just this weekend in the snow, where I was sucessfuly climbing a hill, and basically I had the pedal floored, but the throttle wouldn't go beyond a certain point. It felt like the computer was limitting it.

 

So I brought this up from the dead.. does anyone know if you can retro fit the A-Trac in the earlier models????

 

I have an '02 4Runner. I recently was playing around in some pretty wetsnow about 2' deep. I had the center diff locked, in 4 low.

I was trying to back up on a flat surface. Via my rear view mirrors it appears that when I punched it only one of the rear tires was spinning. The front appeared to kick snow out in front from both wheels alternating between them.

I'm just curious how this system works. Does it only apply pulses to the spinning wheel or does it hold the wheel to allow the other one to spin?

In any case I think I'm going to get a tru-trac in the rear as I'm tired of VSC/TRAC kicking in in 2wd in slightly slippery surfaces with the open diff.

Thanks

 

Anyone, Anyone, I couldn't find much w/o allot of filter in the search of previous posts.

 

I have ATRAC on my 2006 4Runner. I've taken it on trails but don't wheel it like my 1989 truck. Although I don't like all the noise and the fact that a wheel actually gets the brakes, I can't say it's ever failed me. I've always made it up the rock or muddy/snowy/leafy incline. So, I guess as a traction system it's OK. Maybe were just resistant to change. I dunno.

I will say, either lift your latest generation 4 Runner or put rock rails & Bud Builts on or all of the above. On my first trip on a real trail I really did some damage to the fake skid plates they put on these days and really dinged up the undersides off the plastic bumper covers.

You just about need 33s under it and a small lift to not hit the underside. Sad.