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The LSD

14K views 20 replies 12 participants last post by  riccnick 
#1 ·
I just can't seem to understand when or when not to use the LSD.
I currently have a 2011 DC, 5.7 and have a 2017 DC, on the way. It finished production on 10/19/16 and will be here in a couple weeks.

Anyway, in my manual for the 2011, the times to use, or not use the LSD is confusing to me. I'm not really sure what it's purpose is, what it does.

Can someone please clearly explain this?... Thx ahead!
 
#2 · (Edited)
It it is not an actual mechanical LSD.

Essentially "auto LSD" activates a type of traction control that breaks the spinning wheel in order to send power to the non spinning wheel BUT does not cut engine power to the wheels. this is in 2wd. (in a nutshell)

the use can apply to many scenarios depending on what you trying to achieve. For example. I like to use it on boat ramps when pulling my boat out of the water, driving around on partially snowy/muddy/ poor traction surfaces where I need to turn often when pavement is still prevalent. This ideal because it is not good for the truck to make turns when in 4wd hi or lo on high traction surfaces. I also use it when driving on light off road trails when I just dont feel like engaging 4wd. Most of the time I turn auto lsd when ever I know I need to drive around in poor daily driving road conditions - this way i can turn with out damaging the truck. But If the roads are simply snow covered then 4wd will always be the best bet.

Hope this helps.
 
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#6 ·
If am not mistaken when 4hi or 4lo is engaged you will no longer be able to turn on or off auto lsd (so if auto lsd is left on when shifting in 4wd the truck will know that). The 4wd system will work in a different manner once shifted into 4wd hi or lo.....i believe this is where A-TRAC starts to come into play. Lastly, the auto lsd is not an actual limited slip diff. It is completely electronic - the only damage i would think you need to worry about is over working it to the point where the braking system starts to get abused because of the engine not cutting power to the wheels.......

However - if you shift into 4hi some traction control variants are still active. if you hold down the auto lsd button for 3 or 5 secs the traction control system will turn off.

best bet is to read your manual and then ask more questions. Also search Auto lsd in the search bar lots of threads on this.
 
#8 ·
Well, I've gone to "search" and looked up ALSD, also found the above pdf there. I think the pdf is outdated for my 2011 and my 2017 that's on order. Only have a LSD button, no vsc button, or light, but thank you for your time.

My conclusion, seems no one really knows how/when TO USE this feature. It's like it's not needed cuz it's basically the same as ATRAC??? No offense to those that offered help, I truly appreciate it. But there is so many different thoughts on this, I'm still confused. Yes, I have read the manual, and it's vague even to Toyota.

I never thought to search this topic. I'm a bit of a newbie here. Glad to know I'm not the only one in the dark on this.

Would really like someone to make a youtube video that clearly explains and shows what it can do. Maybe that will be me one day.

A real big thanks to all on a subject I did not know was "worn out".
 
#9 ·
Auto LSD is really nothing but a joke. It's a shame they don't even offer a locker as an option. A real locker or mechanical limited slip really can make a difference when driving on snowy roads as well as off-road
 
#10 ·
I've used mine many times. With a 2wd and going across a large variety of terrain, it comes on and does it job often enough. You don't think about it, it is there. The only time I think about it is when I get "stuck". It seems that if not moving and a tire or 2 is slipping that I turn it off so that I can get myself out. Then I go back to forgetting about it.
Dang now I am remembering that I should go buy that mechanical lsd unit.
 
#14 · (Edited)
I wrote this out a little while ago in another thread, hopefully it will help clear things up. This is how my 2010 works, and I believe all 2008+ work this way.

Here are the Systems that the truck uses
ABS - Antilock Braking System. Prevents wheel lockup during braking to keep control over directional changes while braking hard or in a panic situation. A modern 4-Channel ABS system can individually brake each wheel as needed, and monitors all four wheel speeds in relation to each other. The ABS is always "ON". You cannot (conventionally) shut it off.

ATRAC - This is Toyota's Traction Control. It applies the brakes to immediately stop a spinning wheel. Can also retard engine timing to reduce power applied to the driveline. When loss of traction is detected the wheel slip light flashes until traction is returned. This is not related to the Auto LSD function, and this light functions in all driving modes to let the driver know wheel slip is happening. ATRAC is defaulted to "ON".

VSC / TSC - Vehicle Stability Control / Trailer Sway Control. VSC uses the ABS sensors along with steering wheel angle sensor, gyrometer, and yaw sensors to determine if the vehicle is not following the path intended by the driver. Will apply brakes and cut throttle to "steer" the vehicle back into the intended line of travel. For 2011 and later year trucks, the VSC system also incorporates Trailer Sway Control, which detects trailer sway, and will apply brakes to help maintain directional stability while towing. If the VSC system is turned off, Trailer Sway Control will not function. VSC, and subsequently, Trailer Sway Control, is defaulted to "ON".

Auto LSD - Automatic Limited Slip Differential. The Auto LSD senses wheel speed differences between the two REAR tires only, and lightly applies the brakes to add drag to the wheel that does not have traction. This simulates having traction to that wheel and forces equal amounts of power to both sides of the differential. If the initial light pressure does not work, the system will gradually apply more "drag" to that wheel to help send power to the other side of the axle. It does not cut power from the engine. Auto LSD only works in 2wd, and is defaulted to "OFF".

In 2wd:
Normal (no buttons pressed, no dash lights on) = Truck will detect wheel spin and retard engine timing along with application of the brakes to the spinning wheel as needed. Vehicle Stability Control is on. ATRAC is on. Auto LSD is off.

One Push ("Auto LSD" light on) = Same as Normal, but with the addition of the Auto LSD function. Auto LSD overrides the ATRAC function, so the truck does not cut power from the engine. VSC is still on.

One Push for 3 Seconds ("Auto LSD" light on, "VSC OFF" light on) = Same as One Push, but without VSC functionality.

Second Push for 3 Seconds ("Auto LSD" light off, "VSC OFF" light on,"Traction Control OFF" light on) = No functionality of the ATRAC, Auto LSD, or VSC systems. The truck does not intervene when traction or directional stability is lost.

In 4wd High:
Normal (no buttons pressed, no dash lights on) = Truck will detect wheel spin and retard engine timing along with application of the brakes to the spinning wheel as needed. Vehicle Stability Control is on. ATRAC is on. Auto LSD is off (does not function in 4wd.)

One Push ("Traction Control OFF" light on) = Same as Normal, but without the ATRAC function. VSC is still on.

One Push for 3 Seconds ("Traction Control OFF" light on, "VSC OFF" light on) = Same as One Push, but without VSC functionality. The truck does not intervene when traction or directional stability is lost.

In 4wd Low:
Normal (no buttons pressed, "VSC OFF" light on) = Truck will detect wheel spin and retard engine timing along with application of the brakes to the spinning wheel as needed. Vehicle Stability Control is off by default. ATRAC is on. Auto LSD is off (does not function in 4wd.)

One Push ("Traction Control OFF" light on) = Same as Normal, but without the ATRAC function. VSC is still off. The truck does not intervene when traction or directional stability is lost.
 
#19 · (Edited)
@riccnick - thanks for the summary. The only thing I see in my 2016 OM that may be helpful is the addition of Trailer Sway Control which might be good to mention:
"Trailer Sway Control
Helps the driver to control trailer sway by selectively applying brake pressure for individual wheels and reducing engine torque when trailer sway is detected.
Trailer Sway Control is part of the VSC system and will not operate if VSC system is turned off or experiences a malfunction."
Here's the button:
Text Cartoon Line art Coloring book Diagram


And a PDF version of riccnick's post with my comments added (hope you don't mind riccnick!). Should make it easier to print - Feel free to download and print.
View attachment Tundra Driver Assist Systems.pdf
 
#21 ·
Updated my post to include Trailer Sway Control as well, I forgot about this as my truck is the last year without it officially being a "feature". Back in 2011 when they were making a big deal about it, I read somewhere that Toyota had already had the program logic for TSC incorporated into the VSC, but just did not advertise it as a separate feature. I have no idea how true that is, however.

@ChucklesToy, that .pdf looks great! I can see how it would be very handy, you did a great job on the format, very neat!
 
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