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

I'll second this in my SR5. I am not a fan of either so I always drive with them both off. 4wd and 2wd. Same with any car I drive if it is able to be turned off I turn it off. I trust my driving over electronic systems controlling my drive any day call me old school.

 

I do this in every car that I drive mainly because the engine limitation would kick in first, where a touch of brakes on the spinning wheel would have done all that was needed. I have found the Taco to be happily different. It grabs the brakes first, then goes after the engine if it needs to, and it doesn't seem to cut power bad enough to make it feel unsafe. Just enough to bring things back in line.

For those reasons, I have only found myself turning of TRAC / VSC if I am looking to goof off on flat ground.

 

Exactly! For the ORs/Pros, since the TRAC function is backwards, it borders on negligence.

IMHO, the OM is so far off in this matter that I would be in favor of whatever the folks in this thread agree with for descriptions.

 

Everything looks good to me except D12, E12, D17 and E17. Hard to come up with a definition there because it's really half and half. In some circumstances it'll be like open diff no throttle intervention but in extreme out of control circumstances it will be brake and throttle intervention. I'm fairly certain 4Lo TRAC OFF is identical to 4Hi TRAC OFF.

 

You sank my battleship!

 

You guys are doing great... and maybe finding the truth!?

My wife has a 2 year old Corolla, and it has a TRAC OFF switch, which has me guess Toyota wanted to standardize terms... They are not calling it an AUTO LSD switch, even though the Corolla is only 2WD.
TRAC OFF has perhaps changed? I just can't understand why even have it in H4 if it is the same as VSC OFF... only to have stability control without traction control seems odd.

EUREKA!: Maybe, it their wisdom, they made H4 TRAC (the standard, no button push, mode) the same as TRAC was in 2009-2011??? In those years, in H4 had no selectable TRAC OFF... as it was automatically in the 'no engine regulation' mode. They added TRAC OFF selectable quick push in 2012. Back then (2012-2015), TRAC OFF = AUTO LSD... just different names for 2WD vs. 4WD...
The only difference was that AUTO LSD also shut off VSC to 30 mph... From tests by 2012+ owners, in H4, VSC is not off to 30 mph.

Question: In a steep hill climbs, do you 3rd gen 4x4s find it climbs easier and further in TRAC or TRAC OFF? Not running fast and bonzai climbs, just regular 4x4 style driving. In my Tacoma, climbing is far easier with the non-regulated traction control than before without traction control.

 

Without looking at the spreadsheet to see those exact cells, I agree. Tonight I will try and separate into two columns, one for traction intervention, one for stability intervention.... just seems like it might be more confusing than helpful. (Hell, I am still busy confusing myself). If it looks too busy/complicated I will try and just document some other way.

Once that is straightened somehow, I think It will be about new thread time.... everybody here Rocks...thanks

 

I would leave names alone and maybe expand definitions.


I think more testing is needed to verify throttle control/engine cut out. The only time I’ve experienced it noticeably is on the street in two high, when merging right turns on to streets, scary. I might need to go to the dunes and verify in 4wd if the computer pulls engine power and when vs. traction control slowing things down.

 

I triggered mine this morning with a fast right turn on gravel. I was off the gas so couldn't tell if engine mod kicked in but the abs with slip indicator on was firing hard it seemed like on the left rear to straighten the slide. Orientation was nose sloped to left with right turn and left rear of bed sliding to left.

 

I feel confident it does in 4WD with both TRAC and VSC on. I wasn't sure if it would in TRAC OFF if you managed to trigger VSC but @Cold_Toad reported it did.

 

Quote

Question: In a steep hill climbs, do you 3rd gen 4x4s find it climbs easier and further in TRAC or TRAC OFF? Not running fast and bonzai climbs, just regular 4x4 style driving. In my Tacoma, climbing is far easier with the non-regulated traction control than before without traction control.


As seen in my video. The truck made it up the hill easier and further in TRAC, the default setting when switched to 4low and not pressing the vsc button.

I would not have made it up if TRAC OFF had been on , illuminated on the dash, and activated with a short press of the vsc button.

I can go test on a smooth steep uphill and see which mode climbs better at the same throttle position engine speed and gear at a later date.

 

Ok test engineer hat on time.
To test engine regulation and differential breaking (For stability control), Jack all 4 tires up and put it on good stout jack stands. Put vehicle in test condition (maybe 15 mph) and input large steering input.

I theorize the yaw rate sensor will show zero but steering angle with large wheel speed will cause a big mismatch to the computer and fire off brakes and possibly throttle cut.

Not sure, but safest thing I can think of for the bench test on 4hi and 4lo. Unfortunately I don't know when I will be able to do it, might not be until next week.

Note, just jacking the rear up on 2hi gives it a bit of conniption because front wheel sensors indicate zero speed, so it thinks it's spinning the wheels I assume.

 

Be careful with that. With the rapid change in wheel speed when the system clamps down, it could pitch you off the stands. Maybe give yourself some room, have chocks near forward and aft (be sure to account for the scrub radius), and cover the brake? Or if you can, strap the front and rear to a solid object like they do on dynos?

What I have been trying to search out is a loading dock, where the truck ramp is either locally raised or sunk. That would be a great spot to flex out the suspension. The folks who made this vid did a bunch of similar ones:


There is one behind my office, but it is too shallow. Every other one that I have searched out is either on level ground or uses a vertical retaining wall.

 

Yep, could be very scary test, but not as bad as the two wheel jack test I think.
Have to start slow. For this test I think support on the frame and strap diagonally 4 corners and a couple of straps vertically. The good thing is it easy to start with slow speed and small steering input. Not trying this at 60 mph in 4hi...

(Going to have pitch, roll, and yaw forces, but that truck is heavy...)

 

Haha! Yeah, progression is key.

I kind of think your two wheel test setup is pretty safe comparably.

 

I have been watching a few of those videos recently. A really creative and elegant way to do a test of traction control. Unfortunately around here, it seems like most of those loading docks are sunk straight down, with guard-rails of some kind at the drop-off.

 

If I can find one of those, I promise to put it to good use and abuse.

 

I mentioned this a while back. Reminded me of the “safety” sticker they put on the driver’s side door for the locker.

 

So I am second guessing myself, so somebody double check me WITHOUT LOOKING AT MY TABLE.

When in 2WD and 4Hi, the sequence of modes you get from default -> short press -> long press

2WD = (TRAC&VSC) -> (AUTO-LSD) [same as TRAC&VSC-OFF] -> (TRAC-OFF&VSC-OFF)
4HI = (TRAC&VSC) -> (TRAC-OFF&VSC) -> (TRAC-OFF&VSC-OFF)

WTF is that,
2hi short press is traction on and stability off
4hi short press is traction off and stability on

I am so second guessing myself. If I am right, is anybody else think that is retarded?

 

I feel like most everything has been brought to light. Here's my crack at backing up and explaining it all as simply as possible. With the right definitions of TRAC and VSC I feel like everything falls into place and it aligns with what we have seen from testing. Maybe Toyota didn't jack it up as much as we thought, they just didn't explain how the features work well enough.

These are the 6 traction aids that are available.

Definitions per owners manual Page 267.

VSC (Vehicle Stability)

• Helps the driver to control skidding when swerving suddenly or turning on slippery road surfaces

TRAC (Traction Control)

• Helps to maintain drive power and prevent the drive wheels from spinning when starting the vehicle or accelerating on slippery roads

AUTO LSD

• The AUTO LSD system aids traction by using the traction control system to control engine performance and braking when one of the rear wheels begins to spin. The system should be used only when one of the rear wheels spinning occurs in a ditch or rough surface.

A-TRAC (Active Traction Control)

• The active traction control system automatically helps prevent the spinning of 4 wheels when the vehicle is started or accelerated on slippery road surfaces.

MTS (Multi-terrain Select)

• Multi-terrain Select is a system that improves driveability in offroad situations.

Rear Locker

• The rear differential lock system is provided for use only when wheel spinning occurs in a ditch or on a slippery or rugged surface.

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, CC and the rear locker

It’s important to define these traction aids a bit more to understand the different drive modes that are available on a Tacoma. Toyota left a good bit out in their definitions.

VSC 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 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 cutting engine power as well as 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 is a 2wd only mode that does the same thing as TRAC but it will not cut engine power. This is useful for powering out of situations where TRAC is failing to get you out because it is constantly cutting engine power due to loss of traction.

A-TRAC 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 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.

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

Let me know if you guys see anything that seems inaccurate.