July 7, 2023

2023 4runner - Locker, A-trac, Multi-terrain, Crawl control

This is all the stuff that you presumably paid the extra money for when you selected an Offroad trim model. If not, you should have saved money and got yourself an SR5 (which is still a great vehicle).

I found the following simple explanation enjoyable: 

4WD Low
Atrac turned on
Locked rear dif

GOES LIKE HELL in just about every off road condition.

That's all you really need to know.

What do I have overhead?

I do not have DAC (Downhill Assist Control). This would keep my downhill speed under 15 mph (but must be engaged only when stopped). But I don't have it, so never mind.

Overhead I see 3 buttons and 2 knobs.
There is an "SOS" button also on the far right that we won't talk about.

The 3 buttons are, from left to right:

An icon of a vehicle with curved lines below the wheels and the word "OFF"
A-TRAC
An X on the rear differential (the locker)

The first button is auto LSD. I am confused by this. Some literature says that it works only when in 2 wheel drive. Other says that it only applies to AWD vehicles (i.e. the "limited"). But the button is clearly there on my offroad premium. Maybe it is something I can activate when in 2 wheel drive when I don't want to go whole hog and shift into 4x4? But the button is labeled "OFF" implying that it is on by default and I press the button to disable it. But the owners manual says to push the button to activate it.

The next button is A-TRAC. You must be in L4 to use this. To shift into L4, stop the vehicle, shift to N, shift to L4. Then push the A-TRAC button. It only works for speeds under 4 mph

The next button is the rear differential locker. It will only work in L4 and should only used for short intervals when it is required. It deactivates ABS, Hill start assist (hey! good idea), and multi terrain.

The two knobs are "crawl control" on the left (with 5 settings, 1 mph to 5 mph) and "multi terrain select" on the right. The MT select knob spins endlessly in either direction, but there are only 4 modes. See below for details.

Videos by Overland Pacific

This series of videos seem good. The guy has a decent microphone, puts real effort into the video production, makes it worth your time to watch the video. He doesn't ramble on about his dog, his wife, the weather, every other vehicle he has owned. And the videos are not excessively long.

You can look up these features on the forums, and it becomes clear pretty quickly that most people don't have a clue what they are talking about and all kinds of misinformation is being cycled around. As near as I can tell, the above videos are giving authoritative information.

This guy has the factory locker on the rear axle and an ARB air locker on the front axle.

The following are by and large my notes from watching his videos.

A-Trac and MTS

You have to understand both MTS (multi-terrain select) and A-Trac to know when to use one or the other. Both are about coping with wheel spin.

A-trac detects wheel spin and applies the brake to that wheel, this delivers torque to the other wheel on that axle and allows you to move forward. A-trac uses hard brake control, is for low speeds, and is for getting moving again once you are stopped.

MTS is designed for use while in motion. It is very different from A-Trac. A-Trac aims to entirely stop the spinning tire, but MTS aims to allow controlled amounts of wheel spin. A-Trac uses only brakes, while MTS uses both brakes and throttle control. Be aware that when using MTS you won't be the only one controlling the throttle.
MTS offers 4 settings: MTS is for active driving at low speeds (under 7 mph). Unlike A-Trac, MTS can be used in both 4-low and 4-high. However only "mud and sand" will work in 4-high.
Using MTS in 4-high can be better than using 4-low when trying to get moving on ice.

Crawl Control

You get 5 settings (1,2,3,4, and 5 mph). All you do is steer. You will hear a lot of noise.

To engage it, you must be stopped in 4-low, with shift in "drive", and your foot on the brake. You can change speeds while moving. Toyota recommends only 1 and 2 for downhill and 3-5 for uphill (anything goes on the flat). Some of this may just be common sense safety considerations.

Crawl control will cancel if the transmission or brakes overheat. It will also cancel if you open the driver side door. Crawl control cancels at speeds over 15 mph, if you shift out of drive, if you shift out of 4-low.

Even though Toyota doesn't list it, he says he is most impressed by crawl control on rocky uphills. Downhill works equally well, but the concern is what would happen if the system overheated and canceled, you would need to be alert.

What about the locker?

You definitely can use the locker and A-Trac both at the same time. A-Trac only works under 3mph and will disengage itself over 3 mph.

With the locker engaged, A-Trac is controlling the front wheels and the locker is an even "better yet" solution for the rear wheels.

Have any comments? Questions? Drop me a line!

Tom's Auto repair pages / tom@mmto.org