DIALS/ BUTTONS/LIGHTS for 4WD/TRACTION CONTROLS

Nice write up, David!

 

I've gone down some pretty steep hills in snow , slowly , with my foot on the gas in 4L low gear , I wonder whether this is for people that leave the truck in D in every situation .

 

DAC can control each individual wheel's brake.

 

I guess I just don't quite understand the fuction of it , you can barely coax the truck down hill in 4L in low gear with gas , so how much slower do you go with DAC ? And furthermore if it works by an application of brakes , I wonder whether it would be advantageous in snow .

 

Per Toyota:
"The DAC system assists engine braking to help improve directional control during descent on steep or slippery surfaces. When in 4WD low range and with DAC activated, if any one wheel accelerates beyond or below a two-to-four MPH low-speed setting, the DAC system will control the brakes to help ensure the vehicle continues in a straight position when going down a hill. The DAC system is automatically de-activated if the driver depresses the brake pedal, accelerator pedal, or the DAC button.
The active wheel speed sensors enable the operation of the DAC system by determining current road conditions. The system designed to determine current driver operation through an accelerator pedal angle sensor, master cylinder pressure sensor, and the setting of the L4 position switch. DAC next determines its target vehicle speed of two-to-four MPH based on road surface and vehicle driving conditions. When the vehicle accelerates during descent, allowing the vehicle speed to exceed the predetermined speed, DAC is activated. The DAC system will calculate the required brake hydraulic pressure for each wheel, allowing each individual wheel to meet the target vehicle speed."

 

Interesting , thanks

 

I've only used it a couple of times, more playing with it than anything. I have no idea how well it would work in snow. We don't see much around here.

 

Great writeup and pics, David K. Thanks for taking the time. Got my truck two weeks ago and can't wait to mess around with all these functions.

 

Have Fun! It is a TOY afterall!

 

Looking forward to reading more from you and others who have 'played' with their new Toy!

 

The DAC is described above and the recent thread on using DAC reminded me of this one.

 

The "A-Trac" works just in L4, the "TRAC" works in H4. If that is right, there is any "TRAC" light? How I know that the TRAC mode is on and the VSC is off?

 

Amen!

 

TRAC is the standard mode. Lights only in TRAC OFF/VSC OFF modes. TRAC OFF mode is AUTO LSD which is really TRAC without engine regulation. VSC is off to 30 mph. VSC OFF MODE is both the VSC and TRAC off for open differentials and no stability control unless you drive dangerously.

Yah lots of drive modes, but they're fun!

 

So, no rear LSD without "engine regulation" in H4? That is why I want to know about, H4 with LSD?

 

Don't have it yet, but want to know how it works. Will buy one in three weeks, not sure what model yet.

 

Great coverage, vote for a sticky on this one.

This weekend gave the new truck a try, shifting from 4H to 4L kept getting a flashing light saying 4L and a beeping sound with each flash. Called the dealer from top of the mountain, they said give it another go, and worked fine?? Also the hill was really steep in several spots for maybe 1/4 mile at a time. Switched on the down hill assist and never had to touch the brakes, rough rocks, worked like a champ.

 

In my 2010 Off Road TRD 4WD... I have Limited Slip TRAC (without engine output regulation) in H4 (on the front and rear)... and in H2 on the rear only when I am in AUTO LSD.

In my thread on A-TRAC and the other traction choices that the juveniles here are trying to tear up, I have listed the NINE DRIVE MODES... that we have either by doing nothing, or pressing a button or turning a dial. Here is another way to describe the 9 drive modes:

By Doing Nothing:
H2: TRAC with engine regulation
H4: TRAC without engine regulation
L4: No limited slip whatsoever.

By Pressing a button:
H2: TRAC OFF MODE is AUTO LSD MODE (TRAC without engine regulation)
H2 & H4: VSC OFF MODE for no limited slip whatsoever (stop vehicle and hold down button for a few seconds to activate, press again to return to TRAC ON).
L4: A-TRAC ON for extreme four wheeling with near 0 slip front and rear when traction is lost on any one tire.
L4: Rear Differential Locker, with open front differential.
L4: Rear Locked + A-TRAC if you start to spin the front tires, let A-TRAC take over... like letting a genie out of a bottle!

 

This where reading the instructions really helps... In your sun visor is a card that explains to go into or out of LOW RANGE, you must stop and put the tranny in N (Neutral)... not P Park... then turn dial to L4 and put truck in Drive, or even lower gear depending on how steep you are climbing... Also, if a 2009+ Tacoma, press the A-TRAC button once (On the Off Road TRD only) and that will make the L4 twice as powerful as the spinning stops and the traction tires get the torque to roll you ahead... Don't be afraid to give it the gas to climb or crawl over an obstacle.

 

In recent months, we have learned that the 2012 and 2013 4WD Tacomas have an additional traction mode, and change of names for the previous standard mode, in H4.

The new mode for 2012+ (in H4) is TRAC, and is now the same as TRAC is in H2, traction control with engine output regulation.

The new name mode is 'TRAC OFF' and is the same as what was called 'TRAC' before (in H4). The mode is traction control without engine regulation. This is the same as AUTO LSD (H2) but in H4.

IMO it is sad and makes things more confusing that they didn't call it 'AUTO LSD' in H4 instead of 'TRAC OFF'.

2012+ TRAC OFF MODE is traction control without regulation, so more traction control over standard TRAC, as is AUTO LSD in 2WD.

As always, to actually turn TRAC 'off' is to use the VSC OFF MODE (both TRAC and VSC are off).

VSC and TRAC are always on together EXCEPT in 2WD's AUTO LSD where VSC stays off until 30 mph is reached. This would have been great in H4 to silence the annoying beep-beep-beep of the VSC warning you that it is working to correct you, when you are sliding around in sand or mud, off road.

As I have not driven a 2012+ 4WD, I welcome corrections to what I have come to understand from your input. I also would greatly welcome a 2012 Toyota Tech Chart like we have posted for the 2009 traction/brake control changes...