Question about Auto Limited Slip

This is my first Tundra and first post. The window sticker reads, "4WDemand Part-Time 4WD w/Elec Controlled Transfer Case and Auto Limited Slip Diff."

Reading through the owners manual last night I stumbled on some wording that Auto Lim Slip is only for 2WD. Do they mean 2WD Tundra 'models' or 2WD 'drive mode'? Is that even correct?

Do I have to be in 2WD, or switch traction control off? Does TC have to be on? Do these matter for Auto Lim Slip Diff to work?

As an aside, my Ridgeline was full time AWD with specific modes for snow, sand, mud and normal. My particular Tundra does not have the TRD offroad package although I know the TRD trucks have these modes plus others. (My Tundra has the auto leveling pneumatic rear suspension).

Anecdotally, the way it worked on my Ridgeline, when I was stuck in the mud, if you feathered the gas it wouldn't move unless you had enough speed difference between the spinning wheel and the one not turning, but if you punched the gas it would see the difference and apply brake to the spinning wheel causing both of them to turn and move smartly out of the stuck predicament.

For the Tundra I would have thought it should be enough to just be in 4WD, and maybe turn TC off, but hopefully not have to go into 2WD for the Auto Lim Slip to work.

 

Hello.

Auto limited slip differential in tundras is nothing more than computer applying brake to the spinning wheel to get the non-spinning wheel going.

 

ALSD works similar to your ridgeline’s system and as @EmergencyMaximum noted - it’s the computer applying the brakes to limited wheel speed. Though, there are some things to note about using it

ALSD only functions in 2wd (on both 2wd and 4wd vehicles), and only at lower wheel speed. If you are in muddy or slick conditions and feed it some pedal, it will only cut power and shut down your attempt. Instead, feed it steady throttle input to raise the RPMs to 1500-1800 and let it do it’s thing. It takes a second to “read” the tire traction scenario, but will bias enough power to move the vehicle so long as one whee has enough traction to do so. You’ll hear the ABS clicking and clunking which is a good sign. Hold it steady and pint it where you want it to go. I’ve crawled through ditches flexing out the suspension using the feature with success.

In 4wd, Toyota no longer calls it ALSD, but rather ATRAC, which is the same thing just in 4wd. The torque biasing program is different from 2wd to 4wd (you don’t want the front brakes applying in 2wd, for example) so they just call it something differently entirely.

ATRAC is also great for loose terrain management where wheel speed is kept very low. In mud or other terrain where higher wheel speed is desired, disable the ATRAC and/or traction control and let it eat. That usually requires a few push/hold button procedures.

There are some very big differences between the Ridgeline AWD and the tundras selectable 4wd. AWD on the ridgeline is a part time system - it runs in 2wd then automatically selects AWD if it senses wheel slip. There is also a differential between the front and rear axles in the transfer case; this is necessary for operating 4wd on dry pavement (making it AWD instead of 4wd) but just like a standard open differential in your axle, power flows to the path of least resistance and you can get one wheel spinning while the others r standing still. That’s why it’s necessary to use the braking system to limit wheelspin.

The tundras 4wd system locks the front and rear driveshafts together pushing a 50/50 torque split front to rear. The brakes only need to differentiate side to side on one axle rather than try to manage torque for all four wheels, if that makes sense. This system is generally more robust and effective in off pavement or low traction situations, but is not suitable for high traction like pavement as all four wheels turn at different speeds in a corner.

To confuse the mix even more, older Gen sequoias have all drive modes - 2wd/AWD/4wd/4Lo/4LoAWD. They use a true helical gear type limited slip differential in the transfer case to bias torque front to rear, keeping all the torque from being sent to one wheel, while differentiating front to rear so it can be driven on pavement like the ridgeline. But push a button and it locks the front and rear axles together like your tundra for true 4wd.

Just trying to help muddy the waters a little for u…