Why the auto LSD on a 4x4? (non OR)

all I was asking is if I have a front LSD and a rear LSD

I understand I didn’t get the rear locker because I wanted my truck to color match and not look like I love chrome... because I don’t,


But what I just read is I have LSD in my front diff as well as my rear diff, On my TRD sport,


Simulated via breaks? Can you really call it LSD at that point

 

Correct, no truck 09 and on has had an actual mechanical clutch pack LSD in the rear only. No 2nd gen (or any tacoma... 1st, 2nd, or 3rd gen) have ever come with anything other than an open diff up front. We dont get the cool front elockers like the hilux does overseas *cry*

 

Auto LSD/ TRAC does work up front though

 

As simply as I can state it , YES in 4H you have electronic LSD both rear and front. It is an electronic LSD system not mechanical.

 

Just to be clear:
AUTO LSD is a 2WD mode, so the rear only.
TRAC and TRAC OFF work all four wheels in 2WD and 4WD-HI.

"LSD" in AUTO LSD (limited slip differential) is a poor name Toyota used, along with "TRAC OFF" in my opinion because the differential is not where the limited slip is being applied, so it confuses people.
TRAC OFF, as stated before, is not TRAC turned off, but a stronger TRAC with the engine regulation turned OFF.

 

Not sure if there are variations on this in different years, but mine does *not* apply any kind of engine regulation in any mode while in 4WD. There's also only 2 modes available on mine in 4WD..... TRAC with no engine regulation (default), and stop and hold the button until it completely shuts down.

 

Great information here on a subject that's as clear as mud in the Owner's Manual. So our trucks do not have a mechanical (internal / differential clutch actuated) limited slip function which would available full time with no need to engage or disengage it. But they do have a brake actuated limited slip function that works by braking the wheel that's spinning faster. The advantage of this system is that you get limited slip functionality without the extra parts that eventually wear out and you can turn the functionality off.) I had limited slip axles front and rear on my 1995 Ford F-150 (Yes, they were an option.) and it was pretty weird when you stomped it in low traction situations. (But it did get me out of some pretty nasty situations.) The disadvantage of our system is that one has to manually select / de-select the functionality. And if one does not understand what the different options are, you can get (or stay) stuck when in actuality, with the right functions selected, you could get yourself out.

That brings me to my actual question. A good friend of mine told me when I bought my 2014 Tacoma TRD Sport that if I wanted maximum traction, I should put it in 4Hi, then press the Trac button on the dash briefly. (Not hold it until the Trac Off light comes on with it.) His reasoning was that this would give me 4 wheel drive with (brake assisted) limited slip front and rear. Is that correct?

 

I remember drilling through all of this when my truck was new, but last time I needed to get out, I just engaged the locker.

What is the real difference (at low speed, say, parking spot example from earlier) between A-LSD and engaging the locker?

Locker is a bit of a pain once you’re already stuck due to being mechanical, while A-LSD is electronic.

Anyone push the A-LSD?

 

A locker turns your rear axle into a spool where each side is locked together. That means in a tight turn, your inside wheel is going to chirp / chuck as it tries to make the same number of revolutions as your outside tire. Some folks say both tires will chirp since they're fighting each other.

With limited slip, the system is just trying to prevent one tire from spinning faster than the other. A clutch based system does this by sending more power to the wheel that's not slipping. In a brake based system this is done by braking the wheel that's spinning faster. In either case, you won't get much, if any chirping. If you're really in deep tapioca, I'll take a locker any day of the week.

 

Last time I needed it, it was just a deep sand parking lot. Took the open parking spot but was only digging in when trying to back out.

No issue engaging the locker and getting out. But, forgot I had the A-LSD option, too. Maybe would have been sufficient but wasn’t willing to dig in deeper in front of all the soccer moms in 4runners.

 

Also, what’s difference between taping the button and holding it? One has the traction control disabled but the other keeps it enabled? That’s what I infer from the dash, anyways.

 

This is correct. You can get the same effect in 4 low if you cut the yellow wire in the "yellow wire mod"

 

Man, I have posted it so much, but that's ok...

Tapping the button (moving or stopped) is for Auto LSD in H2 and TRAC OFF in H4 (2012+). Auto LSD and TRAC OFF are both full power (no engine cut) limited slip. 2009-2011 is already in the stronger mode in H4 and no button push for them.

Stopping and holding in the button is for VSC OFF and turns off both TRAC and VSC for ZERO traction control, ie open differentials.

 

Yes, many times in the rain (no snow in San Diego), but mostly for fun.

A locker splits the power evenly between the two tires and prevents one from slipping. You will have a hard time turning with the locker if on dry ground. TRAC and AUTO LSD or TRAC OFF use sensors to detect tire spin and will apply brakes to that tire so the other can have a better influence on moving you.

 

YES

 

Your signature doesn't say what year your truck is, but 2009-2011 only had two modes in H4: TRAC and VSC OFF. TRAC for us (in H4) is the same as TRAC OFF for 2012+, only we don't have to push a button.

 

Thank you to Pigpen and David K for their answers / replies. Nice to have folks like you around here!

 

awesome. Thanks for the details. That’s along what I recall what is the behavior with no buttons pressed? Open diffs?

 

No button pressed is TRAC (TRACtion control) or "light" limited slip where if one tire loses traction (spins) the system cuts the engine output and may also apply brake pressure to just the spinning tire(s).

A quick press, moving or stopped, turns OFF the engine regulation feature giving you max power to try and move from a stuck.

Stopping and holding in the button for VSC OFF is to not have any limited slip action or stability control. However, if you are driving dangerously, the system will come on to try and prevent you from crashing.

I suggest you get your Tacoma off the pavement and play with all the drive modes if you can. That is what I did in 2010 and inspired me to do write-ups on what I experienced. Now, to be fair, I did get a lot of data from TW members, some no longer on TW, with these systems but I would learn there are definate differences in them and how all of us absorb that data. That is why I explained them using different wording, many times... and like in this thread, some still have a hard time absorbing it all. Again, a lot may have to do with our driving habits as well as how confusing the Toyota names are for some of these modes... I mean "TRAC OFF," really? LOL

I like TRAC I and TRAC II instead of TRAC and TRAC OFF or instead of TRAC and AUTO LSD!

TRAC I (TRAC) is limited slip using engine regulation (throttle cut) and braking.
TRAC II (AUTO LSD & TRAC OFF) is limited slip using braking only.

Now, for the Off Road 4x4s, there is A-TRAC... maybe call that TRAC III in this example? A-TRAC is pretty close to having front and rear locked differentials but the locking (actually matching tire rotation across the axle) is automatic and only locks when there is tire spin, making steering easy.
TRAC allows some slipping and A-TRAC allows almost none when it is active (A= Active Traction Control). The third gen automatics have an advanced A-TRAC called MTS (Multi Terrain Select) that adjust the A-TRAC sensor actions for various surfaces. They also have CRAWL which is like cruise control for low range driving, very much like the DAC we have (Downhill Assist Control) where we don't touch the gas pedal or brakes except to override DAC.

 

Awesome post. Your efforts are well appreciated!

I agree, I need to take my truck out and play with the buttons again. I did it when I first got it but have only since when needing it. In those cases, I’ve gone straight for the locker after getting stuck as I only needed a bit of help but didnt want to mess around and dig in deeper.

I need to see what the A-LSD can do.

In my mind, I do my approach with the A-LSD when I think it’ll get tricky, and resort to the locker once I get stuck?

Completely forgot the button was there.