4WD system differences

I'm new to my 19' Limited DC, coming from a first gen TRD. I have questions about the system and features. I haven't RTFM yet but sometimes you people here do a better job of explaining what works and how.

First, I do not see a "trac off" button. Is the trac system going to hinder my ability to get some wheel spin up for tricky terrain? Do I even have a trac system?

Second, what's the deal with the "auto lsd"? Is that just a glorified system to use the brakes to transfer power to another wheel? Does it work all 4 wheels or just the rear?

Even tho I have a plow in my 1st gen I rarely ever needed the locker.... only if I got hung up on a snow bank or something. I do NOT plan on plowing or off roading the 19' but I did buy some GY Ultra Terrain tires which I'm sure are going to suffice for anything I throw at the truck....hopefully!

 

This thread describes everything pretty well: https://www.tacomaworld.com/threads/3rd-gen-traction-control-modes-explained.530695/

 

The "Trac off" button should be found in the overheard console. It should cycle through Auto LSD with quick presses and with a long press ( about 4 seconds) it should shut off Traction control.

Auto LSD is simulated limited slip differential that uses ABS and brakes to transfer power from the wheel without traction to the wheel with traction. The ABS will apply the brake on the spinning wheel to force the nonspinning wheel to turn. This system only works in 2hi.

 

Thank you.....I would have preferred an OR version but I found this at a VW dealer that was on the lot for 177 days, they were asking 39,995 and I offered 34,500 and they took it!
I got almost 5000 dollars off book so I couldn't resist even though it doesn't have an MT.

 

So in 4 low I'm straight up open diff 4WD? No trac, no LSD?

 

Yes.

 

Now swap it for the OR you wanted.

 

Open diffs in every trim except the off-road and pro. You can add aftermarket lockers to any trim.

 

Is it different for different trims or model years?

Auto-LSD works in 4-LO on my '18 Sport MT... The first time it kicked in I wasn't expecting what it would do, it actually stalled the engine because I wasn't giving it enough additional throttle.

 

From the manual, page 251 and 252. On the first page, second section, it states can be used on 2WD models and in 2WD mode on 4WD models. Auto LSD is only available in 2WD regardless of model.

 

That's interesting...
Some type of system definitely kicks in any time the tires break loose while in 4-LO. It fully feels like the brakes automatically clamping down on the slipping wheels to divert the torque to the wheels with traction. Whatever it is, it's not two open diffs operating just nakedly.

 

TRAC operates in 4lo on trims other than the OR and Pro. See link in 2nd post.

 

Ah, Ok. That would be it then (great link BTW, Bookmarked!).
I had seen Auto-LSD in the OM, but missed that it's called TRAC in 4WD (indeed the OM is a bit convoluted as to all the modes and their names & functions).


Alright, carry on fellas!

 

Auto-LSD is not called TRAC in 4wd. They are two separate traction control modes. There’s a fair amount of misinformation on the web that labels the various traction control modes as Auto-LSD, but in the owners manual Auto-LSD is one of several modes.

I think of TRAC as a general purpose on-road nanny that is always available, whereas Auto-LSD is for getting unstuck when in 2wd. I use it in the winter to get out of parking spots and intersections when switching to 4wd is inconvenient.

 

Honestly that’s the stupidest feature I’ve ever seen on a truck with 4wd. WTF do you need a pseudo rear lsd that only operates in 2wd? I can rationalize conditions where you wouldn’t want it to engage in 4wd but isn’t that what the switch is for?

 

I don't think you understand. It also operates in 4hi. So far, this truck has not got stuck and all features work as advertised. Where you need a 2wd low mod is for those that have manuals and want to back up a trailer. Helps immensely to keep from slipping the clutch.

 

Same reason you would want LSD in a RWD car - for when you need it. The purpose of LSD isn't to get you unstuck, it's to direct power to a wheel that has traction. This can be used to help you in a situation where you're stuck, but more generically, it's for when one wheel has traction and the other doesn't, so it could be while driving on a wet road hitting a puddle and one tire hydroplaning, or turning around a corner, or hitting a patch of snow.

Obviously if you're in a situation where traction is going to be continuously challenged you'd want to put it into 4WD, but that isn't practical for normal driving.

 

I mis understood, I thought it was only operable in 2wd.

Time to RTFM!!!!
I will say Toyota has one of the best operating manuals in the industry. I’ll have to put it next to the “throne” for my dedicated reading time

 

Like I said, Auto-LSD is useful when engaging 4wd is inconvenient.

For example:

- getting started in a snow/ice filled intersection where the road ahead is dry pavement
- getting out of a snow/ice filled parking spot when the rest of the parking lot is dry pavement

It's very common in cold-wet climates to have roads that are 95% dry pavement and 5% snow/ice. Driving in 4wd is not convenient because of bind up in the drive train when turning.

Also note that Auto-LSD is better than TRAC for getting unstuck. Unlike TRAC, it will not cut the throttle to avoid wheel spin. It also seems like it is more aggressive at minimizing uneven wheel spin than TRAC. In the traction control modes explained thread, I posted some results of some experiments with Auto-LSD. I can't find the post today.

I don't know why Auto-LSD is not available in 4wd. It's possibly because the ABS vacuum booster is not capable of operating on 4 wheels with the more aggressive braking. That's just a wild guess. The OR and Pro have off-road traction control in 4lo (A-TRAC/MTS), but they have a different brake booster presumably to offer more aggressive and longer lasting braking.

See the traction modes explained thread for more info.

 

Auto-LSD is 2wd only. I think you might be thinking of TRAC. See the traction modes explained thread linked above.