Auto LSD diff.........

Anyone know why Toyota discourages everyday use of the Auto-LSD in 2WD Tacos? As a new owner I didn't even know about the dashboard switch to activate it when I had AAA pull me out of the mud. Most vehicles that have LSD are activated all the time, in fact I have never even heard of a switch for an LSD! What's the deal here? Thanks!

 

You have LSD all the time. The auto LSD gives you more traction without throttle control which make it easier to activate when you are going slow.

 

My guess for not wanting to use it every day is because it uses the brakes to manage wheel spin. Continued use of this would wear the brake shoes prematurely.

 

AUTO LSD (2WD) is traction control with brakes but without any engine output regulation. The normal 2WD mode is 'TRAC' and uses both brakes and engine regulation (to limit excessive tire spin).

AUTO LSD is a more aggressive/ stronger limited slip for use IF you get stuck in snow or mud where one tire is slipping and the TRAC mode prevents enough engine torque to rotate the traction tire. VSC is also OFF in AUTO LSD up to 30 mph. Since VSC has been called the greatest advance to driving safety since the seatbelt, running with it off is not going to save you.

To turn on AUTO LSD: Press the button next to mirror controls (vehicle with skid lines below):



These lights will come on:


(The VSC Off light goes out at 30 mph)

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Sometimes in snow or mud, even traction control won't help and spinning the tire(s) to dig into the snow may be needed. To turn off TRAC and AUTO LSD, stop the truck (stop spinning the tires) and hold in the VSC OFF button for over 3 seconds:



To return to normal drive mode (TRAC ON), press the VSC button once more, or re-start your truck.

 

More specifically, they want you in traction control as the default (instead of A-LSD) because if you're reducing engine output while modulating the brakes, it's less wear on the brakes and less likely to overheat them in bad weather.



Responses to wheel slipping:

Traction control: Brake slipping wheel and reduce engine torque.

A-LSD: Brake slipping wheel.

 

Trust him, David K is our local A-TRAC expert.

 

Thanks to all for the info. I thought I read the whole book when I got the truck new off the lot last December, but I guess I blew it on the LSD.

I suppose I really didn't need AAA to yank me out of the mud. With the truck on a 45 degree angle, the right rear wheel in a hole down to the axle, the AAA driver asks me "has that thing got 4WD?". I'm thinking to myself, if I had 4WD, would I be calling you? Next time, I will remember the dash-switch.

 

The book is real lacking on the traction controls... I read it a lot when I got my 2010 (the salesman couldn't help me, and the service dept. was real vague on how it all worked). With help from TW, I got a lot of details, then I really tested my truck a lot to see how they all worked. With 9 drive modes to pick from, there is a lot to play with on the 4WD Off Road TRDs! Happily, the standard mode in H2 and H4 is the best for nearly any condition. Pressing the A-TRAC button in is the only thing you need to do when you go into L4, so it is always on standby if you loose traction in low range.

 

I got this question sent last night and it is of value to others here perhaps, so I think it is valuable to share:

"David I was wondering if I could trouble you for some help understanding how to use my 4 wheel drive. I have read all your posts and not being very mechanical minded (& older) I mis a lot!! I have an ("09) Tacoma access cab 4x4 without ATrac, With VCS & RSCA buttons.

Question, if I am driving along and the weather turns bad & I want to engage my 4 wheel drive should I turn the switch to 4H or should I push the VCS button and then 4H?

Question 2- If I am leaving home and the weather is already bad should I push the VCS button for 3/5 seconds and then engage 4H?. Or should I just engage 4H and forget everything else?

I do not "off road" I just like the 4x4 feature as a safety valve, but I would really like to know how to use it in these situations. I have no Idea if you will get this or not, if you do, Thanks for reading it, and More Thanks if you answer, ***"

Hi ***,

These are great questions, and I will post this without your name because it very well could help others!

The RSCA button is to turn off the Roll-Over Side Airbags if you are doing some crazy off roading and don't went them to deploy.

The normal mode when you start your truck should be fine, always! This is H2 (2WD HI) with TRAC. If you push the VSC OFF button in 2WD, it just changes from TRAC to AUTO LSD... which really is a help to those without 4WD, as it is a stronger limited slip in 2WD (no engine output regulation).

As soon as you detect loss of traction (wet or icy pavement or off road), then rotate dial to H4 (4WD HI)... you are automatically in TRAC, but stronger because there is no engine regulation in 4WD (the same as AUTO LSD in 2WD). H4 will do the most good for you with low traction issues.

If you get stuck in H4 or need extra torque to climb or pull through something, then stop, shift auto. trans. to N, and turn dial to L4 (4WD LO)... There is no traction control in your low range, so tires will spin if they have no traction... turn steering wheel left and right to grab fresh snow/ dirt.

You never should need to push the VSC button or turn VSC off, IMO. However, if you do get in a snow bank and H4 isn't pulling you through and you want to spin the tires to try and grab fresh snow... (and L4 isn't your choice) then STOP the truck, push and hold in the VSC OFF button for a few seconds (works in H2 or H4).

David

 

David,
Noob here. I have a 2010 DCSB 4x4 ( Non TRD)without an A Trac button. I only have a vsc and a ROSC button. I now have 38,000 easy miles on it and want to change the front and rear diff fluid. Is my LSD really just a function of rear brakes? If so i should just be able to change the fluid and ignore the LSD friction modifier additive, correct?
Thanks for all your information.

 

^^^^ No friction modifier needed for the 09+ trucks unless you have a mechanical LSD installed.

Question (do not want to start a new thread) does the Auto LSD work like A-trac for the front wheels as it does for the back? I'm talking non TRD off road too. Maybe this was answered somewhere but I don't recall reading it from previous searched threads.

Thanks,
Nate

 

Yes, your so-called limited slip is just a function of the brakes. You have an open differential in the front and rear of your 2010.

 

Is three years later too late to answer this? LOL

AUTO LSD can't work on the front because it is a 2WD mode. However, if you mean the same process as AUTO LSD but in 4WD-HI (that is called TRAC through 2011 models and TRAC OFF from 2012+), then I will say it limits tire spin, but not nearly to the degree of A-TRAC, which actually stops spin and matches tire rotation across the axle. Limited spin or slip is still better than no limit, off road.

 

Toyota's Auto-LSD uses sensors to detect speed difference between the 2 wheels on an open differential and engages the brake on the faster spinning wheel. In the event that slippage occurs, brakes are applied on the wheel that lost grip and spins faster. In turn, the brake torque is transferred to the slower spinning wheel. Auto-LSD should not be engaged in high grip surfaces because wheel spin at different speeds in a turn. If Auto-LSD is engaged on high grip surfaces, the truck will be difficult to turn.

 

Great info here, The owners manual is very confusing on these issues. In fact useless

 

Glad it helps others!
My 2010 Tacoma (purchased in Dec. 2009) is now 11+ years old and with only 128,000 miles. My driving has really dropped to nothing with my retirement in 2019, and now Covid halting trips to Baja!
The traction controls still work as advertised and other than a freak flashing of the 4WD light a couple times, the transfer case still does its thing!
One thing about driving less, the tires last forever! Hankook DynaPro ATM, 265/75-16.