3rd Gen Traction Control Modes Explained

4Lo A-TRAC is basically 4Lo ALSD but even better. Same with 4Lo MTS but you also get adjustable slip.

 

I found a reason for the ecu to limit speed in H4 and L4. This isn’t related to trac off turning on after 30mph but I found it interesting. The ecu will limit speed if the front diff oil temp is too high.

I’m searching for an easy way to reverse the add position once vehicle is in 4wd. It doesn’t look easy.....

 

Just to be clear, when you say "this" and "it", you are referring to the second paragraph and not the first?

I guarantee you, in my 2010, there is a world of difference between the TRAC in H4 [without engine regulation] and H4 with just open differentials (VSC OFF).

I will need to see models with the quick press TRAC OFF vs. TRAC and see which has engine regulation, because in all previous 2012-2015 discussions, TRAC OFF was the stronger, no regulation mode.

That your research shows another change in 2016, reversing or eliminating that mode, is interesting. I bet a lot of you this weekend do some testing?

If we don't worry so much on what they are called or what lights are on, but just see what works best, that will be the most helpful...

1) Steep, dirt hill climb, standard, no button push, in H4. No speed. Just from a dead stop at the base of the hill, climb up. Mark where you get to (note if there is a lot of tire spin or the engine cuts out).
Back down safely... keep steering wheel straight if the climb was straight!
2) Quick press button (TRAC OFF light goes on), now same climb procedure as #1.
3) Press and HOLD until light VSC OFF comes on, then climb.

For more fun, do more climbs in L4 with or without button pressing and those with the Off Road TRDs, with or without the locker and with or without MTS/A-TRAC and with or without both A-TRAC and the Locker together. You have 10 driving modes at least with 2WD included.

The non-regulated traction mode should take you the furthest.
The regulated traction mode would be slightly less.
The open diff (VSC OFF) should have you spinning tires trying to climb and not go as far up as the other two.

When I did all my testing in 2010, I could climb further in H4 with the non-regulated TRAC than L4. Once I turned on A-TRAC, only then could L4 go further.

 

I believe your 2010 has 4Hi TRAC no engine regulation. The chart below that triangle figure indicated as such with the note 4. I also believe you've done more than enough real world testing to back this up.

What I don't think exists is 4Hi TRAC less engine regulation on 2011+ 2nd gens or whenever they introduced the single VSC button press in 4Hi. I think they are identical to 3rd gens in that they have modes 4, 5 and 6 as described in the OP.

The main reason I think this is the lights on the dash are identical between late 2nd gens and 3rd gens as far as I know.

 

I believe this is before lockers were installed. Stupid video for an example, but damn if the tires aint working magic for a non locked 4x4. If this is TRAC only, then it's one powerful system and it has taken leaps and bounds in this Generation. Take a look at the roosters being applied both front and rear. The fronts seem to be alternating, and Eric caught that in the photo I posted of the ALSD tracks that were left when I went to Hungry Valley. I think I posted that in another thread?? PB's mini roosters act the same (left rear tire). Like there is a puase between roosters. The brake actuating. The left rear is sporting a nice strong rooster too in this video when the right rear lifts for a split second off the ground. I can see why the other thread was misunderstood as ATRAC. Things are starting to fall into place this past hour. This new system in 4LO default is stout for non locked differentials. I've seen too much, and heard too much by now. Whatever it is, it's STRONG. And I can't wait to start applying it and enjoying it even more.

I finally understand why the heads in the other thread were so adamant in their believe that they had ATRAC or something of the sorts that was driving them forward and up where open diffs would never conquer.

https://www.youtube.com/watch?v=odr6OSaiex4

 

Hmmmm.... that video showed normal differentials (to my eyes). Because the tires spun uncontrollably and he could not continue without taking other angles of attack.

If there was traction control, you would not have that kind of spinning and the truck would keep moving uphill. Both tires spun because both had equal traction (or actually lack of traction).

If you have a video of one of the tires on the ground and one off the ground, then you would see the one off the ground spinning (no trac); or slowed way down (brake action on non-traction tire) as the truck moved.

A-TRAC (MTS) totally halts free spin and matches rotation across the axle. TRAC slows down the free spinning so more power goes to the traction tire on that axle. Only the Off Road TRD 4x4 has the hydraulic brake booster needed for A-TRAC to have that near-locker-like rotation matching. All other models have a vacuum brake booster and they cannot totally halt one tire from rotating more than the other one on that axle. They do slow it down enough that in greatly enhances the truck's ability to move on.

 

All other models have a vacuum brake booster and they cannot totally halt one tire from rotating more than the other one on that axle. They do slow it down enough that in greatly enhances the truck's ability to move on.




In my video you can clearly see the front tire in the air get halted by the vacuum brake booster traction control. Once that happens power is transferred to the right front and my truck makes it up to the top of hill.

 

Pay close attention.

In PB’s video, you can see the actuation happening. The mini roosters look more like “puffs.” Those are the brakes firing while the axle is completely on the ground.

 

DesertTaco4x4 beat me to it.

 

Excellent work guys.... This should be a sticky.

 

Once again, pay very close attention. 17-22 seconds into the video. You can clearly see the front left tire actuating and throwing roosters. Rooster, stop. Rooster, stop. Rooster, stop. And finally Rooster, stop. That’s the magic happening.

In PB’s vid, it happens 20-21 seconds into video, left rear. 2 small puffs. Puff, stop. Puff, stop.

 

And yes, at the end of PB’s vid, that left front comes to a halt. All power goes to the right at that point.

 

Great!

 

What I find funny is that a few of us own or have owned lockers and ATRAC and are describing GREAT traction. I’m as happy as I’ll ever be :0)

Both lines from the booster run to this. Must be where the magic is taking place and pulses being distributed?

 

Just looked that up and it is a brake and engine controller. Seems to be the brain of it all. Take a peak at the lower left of the page.

http://www.advics-na.com/AdvicsPages/products.aspx

 

Nice post op. I had a pretty good idea what was going on with these things but this explained it very well. I understand more now.

 

I would say instead of the Booster, the ABS Module is what is being used in Non Off Road or Pro Models.

 

Yes, that’s what I intended to mean, it’s not mechanically possible to modulate all 4 wheels in 2wd because that’s why 4wd exists.

Thanks for doing all this and bringing clarity to a very confusing but rich and exciting feature of our trucks.

 

I think definitive answers could be had if Techstream users could monitor in Active Data which solenoids are firing and when.
FWIW, both vacuum and hydro booster have separate ABS and TRAC/VSC solenoids.


VACUUM


HYDRO

 

This probably belongs in another thread but How does trac and a-trac compare to the torque vectoring awd on the ridgeline? I’m wondering if Toyota is responding to the completion by adding more traction features on all the trim levels.

This isn’t an attempt to bash the taco, I’ve one on order and chose it consciously over the ridgeline. But I’m wondering if it’s apples to apples on the non trd models, and I don’t fully understand the differences between the systems.

https://www.edmunds.com/car-buying/...yota-tacoma-trd-off-road-comparison-test.html