A-trac in 4lo on all 2016 4x4 Models Non Trd Offroad

If you read this thread https://www.tacomaworld.com/threads/a-trac-trac-auto-lsd-explained-easy-to-understand-i-hope.70551/ and substitute TRAC not working in 4LO with TRAC now works in 4LO, then you have the 3rd gen 4WD system... I think that is the only difference.

 

Close, but not quite? We (SR, SR5, and Sport MTs) do not have Numbers 8 and 9.

That is a good thread though. Thanks!

 

Front wheel







Rear wheel



Same set up. We’re crawling on 4’s on H4 and 4LO beyond 3mph.

 

So I am trying to do a pseudo scientific examination of the modes. To try and do the work logically, I always prefer to start with a bench test (if possible). A bench test isn't necessarily going to tell us everything, especially after big wheel spin or when throttle regulation occus, but I think its a good place to start. For my test I am using my 2017 TRD Off-Road (access cab) Auto. I hope somebody will repeat the test using manual tranny and using a non-Off road/Pro.

I am primarily examining open-diff vs brake enforced limited slip operations, at low throttle settings that can be simulated on the bench.
To do the test, I jacked up both left hand tires clear of the floor using floor jacks, with the jack wheels set fore-aft. Both RH wheels were carefully chocked. The steering wheel was maintained straight forward or all tests. For the test, I placed the vehicle into the test condition (by manipulating the drivers controls), placed it in drive with my foot on the brake, observed the dashboard lights. I then took my foot off the brake and observed the dash lights and speedometer, and the tire movements thru mirrors. I then applied a slight amount of gas while monitoring. If the I heard/felt the hydraulic brake actuator fire, I terminated that portion of the test, and assumed some Limited Slip Differential was in effect. If no LSD was observed, additional throttle was applied up to about ~1500 rpm maximum, at which point the test was terminated if the brakes never fired.

For tests that are known to have strong LSD or locking, only very light throttle application was used, to avoid overrunning the wheel chocks, which would have been easy. These were a bit scary. An interesting note, for all modes of brake LSD, the brakes only fire after applying throttle. In drive with LH wheels in the air, no throttle speeds of 4 mph were noted without computer intervention. Only after applying additional throttle did the LSD system activate brakes. Even with MTS active, the speedo indicated 1 mph with the LH wheels just turning away happily with no throttle application, and then even a tiny amount of throttle causes huge hammering.

(Edit to note, I won't absolutely guarantee that this table is error free. If anybody disagrees with any of the noted observations, please let me know and I will double check that particular observation)

My obersvations

 

Agreed on wishing for 2Lo. The reverse gear has me slipping the clutch more than I'd like to when backing into parking spots. Stupid high ratios.

 

Very good, Big White!
As soon as I get a day off without snow or rain, I shall attempt the same experiment with my 2.7 SR manual, and report back.
So far my tests have been limited to off road driving.

 

Nice test! I agree that the setup is nervy though. You do have some safety margin using rolling floor jacks.

I have been thinking of trying something similar using my ramps (I only have one floor jack). One right front and one left rear? That way I can observe the LF tire as the suspension flexes out.

All of the TCS systems that I have seen will allow free movement at idle in 1st gear. Your results there, even with MTS engaged, makes sense. There has to be some built in threshold to account for turns and/or an underinflated tire.

Definitely! Our last three MTs all had reverse ratios that we higher than 1st. I'm certain that the MFGs have a reason for it, but I cannot think of one other than J-turns. You'd think that they'd want to prevent those at all costs.

Also, on Tuesday, I tried a hard launch in the wet using Auto LSD. As soon as I started rolling, I got axle tramp. I rolled off the gas to settle things down, then got back on it. No wheel spin or drift angle was felt up to near redline. Once past some speed around 35mph, the TRAC Off light shut off. Auto LSD stayed lit until I pushed the switch.

 

So in the sport in 4LO, with no button pressed, you DO NOT have the "TRAC OFF" light, correct?
That is definitely different from my 17 automatic TRD Off road, which does have "TRAC OFF" light on in 4LO, until turning on MTS, etc.

I think it is probably time for a new 4wd traction control thread, because it definitely looks like the plot is thickening.

 

Exactly. In 4Lo at startup, I only have the 4wd and LO lights. With my uphill two wheels in snow and two wheel on pavement experiment, I got a TCS light to flash up when pulling out. The Taco moved without hesitation and didn't pull to the right. It might not be a strong function because I could not get a light when playing in snowy parking lots. So, it might let Sports get a bit more initial wheel spin?

I wanted to repeat the experiment with the long push / TRAC Off, but I was in someone else's neighborhood and didn't want to get anyone angry.

I agree. A new thread for all Tacos would be good. Your post and comprehensive spreadsheet would make a good initial post.

It seems that MT SRs and SR5s have the same functions as the MT Sports. So, it might just be SR, SR5, and Sport in on group and ORs and Pros in the other. It seems that AT versus MT might only be the OR A-TRAC function?

 

Interesting, I might have gone SR/SR5 had I known.
Would you be willing to fill out a copy of my spreadsheet, just with the dash lights at least. With those two data's, I will post up a new thread.

 

I would be happy to. I might be able to try the test with ramps this weekend, if I am home. It is 50:50 if will be or not.

 

Crack the code fellas!!!!

 

So I have a 2016 Sport, and when I push the overhead squiggly button down for a few seconds in 4Lo, the "trac-off" light comes on. And that's good?

I want maximum traction in 4Lo (minimum wheel spin), so wouldn't I rather NOT have the trac-off on? Bottom line, what's best in 4Lo, "trac-off" light on, or not?

 

With 99% certainty, maximum traction will be with TRAC turned on, so NO "Trac off" light.
The only thing I am not sure of is if there is any throttle regulation, for cases when you want to get momentum. (But momentum I would assume 4hi, not 4lo)

 

Ahhh... so the happiness over the "trac-off" light was because it was confirmation that apparently the trac is on automatically (default) when in 4Lo

 

That’s where this system shines. Or at least what I’ve experienced so far. All of a sudden, it does it for you, and you’re along for the ride. However, this alsd on all fours goes beyond the 3mph range. That’s what’s bad ass about it.

I’ve seen videos of a lot of different alsd’s. Toyota has a wicked alsd system on the 3rd Gems non OR’s. Honestly, and not leading the cheers, it’s just the truth.

And yes, ya’ll shall see.

 

I believe that is right, and no mods required to get that function. (And the mods are MUCH harder with the new ECU)

 

That's great to know, that at least there is some "extra" help installed for those of us without the locker.

 

I was reading one of these threads yesterday where someone was saying that "Trac Off" was like auto LSD in 4H. I checked that today on my dirt road.

4H with Trac Off light lit spun the left front and right rear tires. The "slip" light did not light up during this.

The "slip" light did light up when the "trac off" light was not lit telling me that the traction control was working. Also the tires only minimally spun then stopped.

 

The most interesting part to me (As a TRD-offroad) is that appears that in default mode for 4Lo, the SR/SR5/Sport is more capable because these default to Trac on, and the off road defaults to Trac off when switching to 4Lo. You have to switch MTS on every time in the automatic.