Hi All

I have a couple of question about Crawl Control and MTS that I don’t see in the manual that I hope you can answer.

First when you use A-Trac and Crawl Control it says you may hear strange noise or feel vibrations when it is operating but it doesn’t mention this in the manual for MTS. It’s my understanding that A-Trac and MTS are basically the same function but MTS let’s you select manually. For those of that have used MTS in the hills do you also hear noises and feel vibrations when in this mode like crawl Control?

Also with Crawl Control I know you can use it independently and with A-Trac but I’m not sure about MTS. With MTS the manual says the CC must be off before engaging MTS but once MTS is on can you then turn on CC and use the two together? I tested it out in my vehicle and I was able to use CC with MTS after I turned on MTS. So it’s it ok to use the two together or not? The manual is not clear on this.

Thanks

MTS, ATRAC, and CRAWL all use the anti lock brake system ABS to pulse brake applications at each wheel's brakes to manage tire slip. The noise is you hear is the rapid firing of the solenoids that are in the brake master cylinder in the engine bay as they operate the pulses of brake pressure. You'll hear those noises in all 3 modes when one or more tires slip. And in the lower speeds of CRAWL you'll hear it most of the time. You'll also feel the jerky motion as they pulse brake applications.

I don't think the MTS or ATRAC functions make any difference in crawl control. It's already on the most aggressive traction control setting. I think effectively anytime crawl control is turned on, it's also about the same as rock mode in MTS which is the most aggressive traction control setting.

I don't know why there is ATRAC and MTS. MTS is the same thing, but with adjustable levels of engagement. ATRAC is a mid-range setting. I just use MTS and almost always end up choosing the rock setting.

What he said. ATRAC and MTS are redundant and while I like that I can use MTS in 4hi, (sand/mud), I really only need the one ATRAC button. Having driven several vehicles over the years with this multi terrain BS I can tell you it is mostly gimmicky. I'm all for using the brakes to supplement cross axle traction but as far as different levels of engagement I agree with Jet Boy, the most aggressive is usually the most useful. I think the only reason offroad and pro models still have an ATRAC button is just a holdover from sr5's. IMO the only upgrade from an sr5 as far as offroad capability is the rear locker, not MTS or crawl control.

Before coming to my 4runner I used to drive an 08 JK. While I eventually added lockers front and rear, when it came from the factory it was just open differentials, not even limited slip, but Jeep used the same "ATRAC" technology, (they called it BLD or brake lock differential), and it worked fine and could even transfer power across the axle with one wheel spinning in the air. Unlike Toyota you didn't have to push a button to turn it on, it was just on and in aggressiveness I would say it was equivalent to ATRAC.

TLDR: using brakes to simulate lockers is a great idea, not as good as lockers, but waaay better than plain open diffs, and cheaper and simpler than adding lockers or limited slip diffs. MTS or other "adjustable terrain settings" is mostly a marketing ploy IMO, while there is some difference in modes, (including throttle response), If you couldn't get through the obstacle in mogul, changing the MTS to loose rock is not going to help.

Yes that’s the way I understood it. They are all basically the same think with minor differences. I think A-Trac and MTS are identical the only difference is with MTS you can select manually where A-Trac does it automatically

What confused me was what was said in the manual. With MTS it specifically says Crawl Control must be off before you can turn on MTS. So why do you have to do this with MTS but not A-Trac? Because the manual specifically says you must turn off CC before using MTS Some people may interpret this as you can’t use CC at all with MTS. But I was able to use CC with MTS in my car but will it cause any potential problems using both together? So I was seeking clarification on this point.

Also I assumed that when you use A-Trac, Craw Control and MTS that they all make unusual sounds and vibrations when the are used. The manual states this for A-Trac and CC but mentions nothing for the MTS at least in my 2016 manual. My guess was whoever wrote the manual forgot to mention this but because it’s not in there it creates confusion.

So my assumption I assume is correct. They all make odd noises and vibrations when in use and CC can be used with MTS but you can use it only after MTS has been engage

Thanks! This was helpful!

I also wonder if later manual cleared this up.

MTS has nothing to do with the ABS system, unlike A-Trac and Crawl. It's essentially a throttle mapping system that changes output based upon the terrain you select. There should be no strange noises when using it, that's why it's not mentioned in that section with A-Trac or Crawl.

A-Trac uses the ABS to act like faux lockers. Crawl controls throttle and ABS to maintain speed on obstacles/terrain while maintaining traction as best it can at all 4 wheels. That's why you get the noise of the pulsing of the brakes when using them.

Crawl doesn't need MTS because the computer is controlling the throttle. However, if you're not using Crawl but are using A-Trac, then MTS might be helpful depending on the terrain.

Hi CajunMike

Thank you. This was helpful but to be honest I’m still a little confused.

The part about why Crawl Control must be turned off makes sense now. Because if both Crawl Control and MTS control the throttle then it’s redundant and the two could potentially compete with each other but I’m still confuse about the traction control.

In the manual it says A-TRAC is a “system (that) automatically helps prevent the spinning of 4 wheels”. For MTS is says it uses “engine control and active traction control system is controlled to enhance off road drivability ”. Because it used the term “active traction control” I assumed this meant A-TRAC. So if MTS is not using using the brakes like a faux locker like the A-TRAC, what is it using for traction control? I’m just trying to understand the mechanics of it all.

Thanks for your help.

Active traction control is not the same as A-Trac. Confusing, I know. Unless you turn it off, traction control is always active, so if you're in MTS and traction control isn't off, then the ABS will kick in if rear wheel slippage is sensed.

Also, MTS doesn't control throttle, it remaps the IO curves (in rock mode, it's more sensitive, so when you give it some pedal input the system applies a greater throttle movement than in dirt/sand mode). It works sort of like a Pedal Commander for offroad, but still requires the driver to actually do all the work.

Crawl actively controls the throttle & brakes when engaged... it's offroad cruise control. All it requires is the driver to steer.

A-Trac is essentially the braking portion of crawl control, but still requires the driver to do all the work. It will kick in when needed automatically, but until there's wheel slippage, it doesn't do anything but monitor wheel speed. It's essentially a 4wd version of the Active Traction control system that's always active under normal driving conditions. The nice byproduct is that it'll lock up a tire in the air, forcing power to the other tire on the ground, acting (sort of) like a locker.

I understand how Crawl Control and A-TRAC works I just wasn’t fully understanding how MTS does. I couldn’t understand how the mechanics of the vehicle allow for wheel slipping in mud and sand but not for rock? So let me see if I understand this right. So when you set it for mud and sand and give it some gas the computer can detect and allow the wheel to spin a little correct? So how does it prevent the sheen from spinning to much? Does it do this by reducing the power just enough to stop the spinning or does it apply a little breaking or a combination of both? I think your saying it’s doing it all through power regulation and no breaking right.


By the way, what exactly is a IO curve” a power chart?

Thanks again for taking the time to explain this.

You can also think of Crawl Control response to the wheels like ATRAC on steroids.

IO = input (pedal) output (throttlebody)

MTS has nothing to do with wheel slippage, brakes, or any of that. There's your problem understanding it. Get the idea that it has anything to do with the brakes out of your head. It's throttle mapping, plain and simple. If you put it in any mode and let off the brakes, the vehicle will (maybe) move forward at idle and nothing more. It attenuates the signal for dirt/sand (increased pedal input equal lesser throttle response) and amplifies it for rock (less pedal input equals greater throttle response).. but you still have to mash the skinny pedal yourself.

Ok, ok now I get it. The first time you said throttle mapping I miss understood what it meant. This time around I did some research and watch a couple of videos and now I understand. Before this I talked to a couple of Toyota dealers and even called their customer service centers and one really understood how the mechanics of it works. I always got a different answer.

So would this be a accurate description then?
“MTS uses throttle mapping software to adjust engine power and torque settings to deliver optimized road performance for the terrain that is selected”

So does crawl control also use a throttle mapping system? And is that why the reason the manual says to turn off crawl control before using MTS is because the two systems may interfere with each other?

Thanks for all your patience in trying to help me understand. I really appreciate it.

Crawl doesn't really need MTS. It's essentially offroad cruise control that uses both throttle and brakes and is all controlled by the computer (all the driver does is steer). It's going to apply however much throttle it needs to maintain the set speed over varying difficulties of terrain, just as it will apply the brakes when it needs to slow down to maintain the set speed. And it will do both at the same time (depending on the situation) if need be.

I'm happy with my ORP, but if I were to do it again I'd get an SR5 and put the difference into front and back air lockers. I don't need all these options just to figure out how to get through a stretch of trail. 4Lo, two foot driving, and lockers would get it done without needing a reference card with a flow chart.

I'm not certain that MTS only changes throttle sensitivity. I think it tunes A-Trac a little more wheel spin for mud where you don't want the wheels to stop at the first loss of traction. Toyota's website describes it as "With five modes to choose from, this system helps regulate wheelspin by automatically adjusting the engine throttle and traction control."

Seems to me that there is a very narrow window where MTS would be useful. There's a very small gap between being able to get through an obstacle without MTS and not being able to get through the obstacle at all.