Mystery button on my 2001 Limited 4Runner dash

I don't have my user manual, not really sure if I ever had one, bought this 2001 back in ~2010...

But I never thought much of this button before, and I've taken my 4Runner off-road in 4WD plenty of times, mostly at the beach, but it works great. Just a pushbutton engagement on the 4H-4L shifter to put it into 4WD.

Initially I thought maybe it engages a rear diff locker, but checking under the vehicle, there is no locker hardware on the rear diff.

Anyone with a Limited recognize this button and know what it does? The symbology on it made me think it had something to do with 4WD, but maybe it's for disabling traction control? Not sure, could use some help!

Thanks in advance!

 

It's for center diff lock.

 

It's on all 4x4 4Runners for 2001-2002. I have it on my SR5.

 

Yep, you have a lockable center limited slip differential you can use in any conditions including on-road.

Just not when locked.

 

Thanks, I feel a little embarrassed I didn't know my 4Runner had that "feature". Not sure how that'll help me off-roading other than I'll need to make sure it's "locked" from now on, would rather have the locking rear diff, like my 2022 Taco features.

 

It really is a great four-wheel drive system, it's funny how it's more advanced than the one they offer now.

If I recall correctly, they discontinued the rear locker availability in 2000, 2001+ got ATRAC instead.