3rd Gen Traction Control Modes Explained

Tacoma's option 6 different traction aids. Toyota's definitions are very vague and create confusion but we are going to clear that up here.

VSC (Vehicle Stability Control) is solely responsible for maintaining vehicle stability. It will accomplish this by cutting engine power as well as applying brakes to individual wheels as it sees fit. It is important to note the difference between stability and traction here. VSC is more concerned about the truck sliding out of control. It is not concerned with a wheel losing traction while crawling through a trail. VSC will kick in for things like swerving for a deer in the road or sliding from a patch of black ice. A yaw sensor and possibly other sensors are utilized to determine if the truck has lost stability.

TRAC (Traction Control) is solely responsible for maintaining traction. Making sure that none of the wheels are needlessly spinning because they have lost traction. It accomplishes this by applying brakes to individual wheels as it sees fit. TRAC will kick in anytime it detects wheels rotating at significantly different speeds – such as starting in icy conditions, driving through mud or snow and lifting a tire while offroading.

AUTO LSD (Automatic Limited Slip Differential) is a 2wd only mode that has TRAC turned on and VSC turned off. Meaning you get the brake simulated LSD functionality from TRAC while preventing VSC from intervening and cutting engine power. This is useful for powering out of situations where VSC is preventing you from getting out/started because it is constantly cutting engine power.

A-TRAC (Active Traction Control) is a 4Lo only mode that does the same thing as TRAC but turned up a few notches. Also, A-TRAC will not cut engine power. A-TRAC provides near locker like performance in that it allows very little speed difference between wheels.

MTS (Multi-Terrain Select) is a 4Lo only mode that does the same thing as A-TRAC but the amount of slip allowed can be adjusted via the various modes.

Rear Locker mechanically locks the rear wheels together.

All model’s get VSC, TRAC and AUTO LSD.
TRD OR and TRD Pro models with manual transmissions get A-TRAC and the rear locker.
TRD OR and TRD Pro models with automatic transmissions get MTS and the rear locker.

So now that we know exactly what all those are the different drive modes are simple. If it’s on, it’s going to do the above. If it’s off, it’s not.

All Models
1. 2Hi TRAC ON and VSC ON
2. 2Hi AUTO LSD. In this mode VSC is off from 0-30mph and on over 30mph.
3. 2Hi TRAC OFF and VSC OFF

4. 4Hi TRAC ON and VSC ON.
5. 4Hi TRAC OFF and VSC ON. In this mode TRAC is off from 0-30mph and on over 30mph.
6. 4Hi TRAC OFF and VSC OFF

SR/SR5/TRD Sport/Limited
7. 4Lo TRAC ON and VSC OFF.
8. 4Lo TRAC OFF and VSC OFF

TRD Offroad/TRD Pro with manual transmission
7. 4Lo TRAC OFF and VSC OFF
8. 4Lo TRAC OFF, VSC OFF and A-TRAC on
9. 4Lo TRAC OFF, VSC OFF and rear locker engaged
10. 4Lo TRAC OFF, VSC OFF, A-TRAC on and rear locker engaged. In this mode A-TRAC will turn off when speed exceeds 3mph.

TRD Offroad/TRD Pro with automatic transmission
7. 4Lo TRAC OFF and VSC OFF
8. 4Lo TRAC OFF, VSC OFF and MTS on (Crawl Control optional)
9. 4Lo TRAC OFF, VSC OFF and rear locker engaged
10. 4Lo TRAC OFF, VSC OFF, MTS on and rear locker engaged (Crawl Control optional)

Spreadsheets created by @BigWhiteTRD

 

A lot of this was brought to light in this thread so take a look if you want to do some more reading.

https://www.tacomaworld.com/threads/a-trac-in-4lo-on-all-2016-4x4-models-non-trd-offroad.437814/

@BigWhiteTRD has an excel spreadsheet that documents these modes for the various models and maps which lights will come on when. Hopefully it will be brought to this thread.

Some testing is still being done by the guys in that other thread. Hopefully the results will be brought here.

This thread is intended to be 3rd gen only. There was a lot of discussion comparing 2nd gens and 3rd gens in the other thread but many requested a 3rd gen only thread so here it is.

 

I would add...
VSC will brake any of the 4 wheels, TRAC only brakes driven wheels.
Crawl control is adjustable DAC(downhill assist control).

 

Something I found in the service manual; I don't know if it applies to auto, manual or both.

 

Seems like an explanation for the C1268 error code. Sounds like if the ECM is saying the truck is in L4 and the skid control ECU is being told the truck is not in L4 this code will be thrown. Or vice versa. If they dont match this code is thrown.

 

You're right... I was reading it as 'AUTO' A-TRAC.


#5 on your list doesn't seem to jive with this.

 

What they are describing in that 4wd paragraph is #6. They failed to mention #5. You get to #5 by simply pressing the VSC off button while in 4Hi. You can do it at any speed and you don't have to hold it down.

 

Latest up-to-date documents to my knowledge

 

@Doggman I posted a bad (low res) pic, sorry, I edited my above post for a larger pic, although the pdfs are available too...

 

My bad, I'll swap them out and add the pdfs to the OP

 

Thanks for converting this to a new thread. Hopefully someone here knows a Toyota engineer who can explain or make sense of #5 for us because I still can't make sense of it logically.

 

Bump for sticky!

 

So vsc can brake any 4 wheels, but modulate engine power only to driven wheels I assume? Why isn’t trac similar?

Also despite some earlier observations in the other thread, there is no equivalent of auto lsd ( I.e no engine modulation ) in 4wd hi?

 

Yes, that makes sense because you wouldn't need to cut engine power to non-driven wheels

Based on testing it doesn't seem so but logistically it would only make sense to have a 4hi -auto LSD mode with a quick push of a button but that doesn't seem like its the case here.

 

Opening post, #5 says Trac is off to 30 mph... Do you mean VSC is off to 30 mph, like in 2WD or the TRAC OFF light is on and it goes off at 30 mpg? Otherwise, good job!

 

Thats where i'm having a hard time understanding still is 4hi with quick press of button

 

I don't even own a 3rd gen, but this is great

 

Haven’t played with 4HI, but I’d like to find out what type of TRAC/ALSD (if any) is happening in default 4LO for non OR’s.

If it’s TRAC, it’s highly advanced.

 

Correct. All testing and documentation indicates there is no equivalent of auto LSD in 4Hi.

TRAC could brake non-driven wheels if it wanted to but that's not it's intended use. Non-driven wheels are just rolling over terrain so their traction is negligible with respect to TRAC. TRAC is to help maintain traction of the driven wheels. If say you were in 2wd and you locked up the front non-driven wheels and they were sliding ABS would kick in for those front tires. Not TRAC. It's kind of semantics in that TRAC and ABS kind of do the same thing by using the brakes to help out but it's important to distinguish the systems and their exact purposes.

And yes modulating the engine will only effect driven wheels because non-driven wheels are not receiving anything from the engine.

No, I do not mean VSC is off to 30mph. It is not the same as 2WD ALSD. The TRAC OFF light is on until 30mph and then it turns off. VSC off light is never on.

4Hi quick press of button is 4Hi TRAC OFF VSC ON. You have no traction control from 0-30mph and traction control is turned back on from 30+. You still have stability control at all times in this mode. Simple as that.

 

So crazy... but, thank you Doggman for doing this! Too bad Alabama is so far away, I would like to go wheeling with you. If you come to the West Coast, I can show you the wilds of Baja!