A-TRAC/TRAC/AUTO LSD Explained (Easy to understand, I hope!)

We call them Toys, afterall!

 

Yesterday, I did a sharp turn on ice. VSC definitely works in 4Hi.

 

What year truck?

 

I have a question

Today after work I started my truck , and got a check engine light and the VSC slip indicator light stayed on solid

I'm getting the codes read on that tomorrow morning , but the thing I noticed is , with these lights illuminated , a push of the VSC button brought up the VSC OFF light but not the ALSD light

Driving , the VSC OFF light would stay illuminated until I went above approx 30MPH , at which point it would go out .

Slowing down below 30MPH re-lit the VSC OFF light

I had thought that with a push of the VSC button , once you drove faster than 30MPH it cancelled the VSC OFF mode , and needed to be reselected with the button , is that not the case ?

 

I know you know these things, but for others, let's review and maybe figure out what's happening in your 2009 Sport:

In AUTO LSD (quick push of VSC button at any speed), VSC is off until 30 mph then it comes on. If you drop back down below 30, it will go off again, etc.

The AUTO LSD is non-regulated or 'strong' traction control. Toyota calls this 'TRAC OFF'.
In 2WD, TRAC is the normal 'on' mode and has engine output regulation.
In 4WD-HI, TRAC is the normal 'on' mode, BUT is not regulated (same as AUTO LSD).

Stopping the truck in H2 or H4 and pressing VSC button and holding it in for a few seconds puts you in VSC OFF MODE (no TRAC or VSC)

Okay, for 2009-2011 this is the drive mode options.

Unless the AUTO LSD light is burned out, I don't know...??? Let us know what the code reader said!

 

My code was a P0456 , Evapporative Emissions fault

Probable cause , a not sealed gas cap or bad gas cap O ring

When the CEL is lit , the VSC system shuts off indicated by the slip indicator light ( not the VSC OFF light ) and presumably in this defaulted CEL mode the ALSD is not an option but pushing the VSC button illuminated the VSC OFF button , which switched on and off at approx 30MPH

 

yes

whenever the MIL is lit, all the electronic vsc defaults to off so that
the problem, whatever it is, does not interfere and possibly make vsc unsafe

vsc only works when all vehicle sensors provide input within expected parameters

 

Now I want to find out a way to trick the ECU into going into this mode , and have it switchable like the ABS bypass mod

 

Thinking further to this post , if the VSC is already defaulted to off with a CEL code , why then would it allow me to select and deselect VSC OFF ?

 

ask toyota not me...many many things seemingly unrelated to
vsc will force ecu to turn off the fancy stuff until code is cleared

the whole list of [what = what] I do not have, but it is known since
toyota started putting vsc and trac in things...codes make system
shut all that down for safety

vsc and trac only work when all systems are go.
vsc cannot work the engine/brakes automatically when
a code is being thrown. it won't do it.

 

All I'm saying is that it seems peculiar that if all TRAC and VSC systems are shut down , that I could still select and deselect VSC OFF

 

Ok, here is how all this stuff operates.

Start in 2WD,

If you start to slip, do this procedure below

 

Lmao...

 

That is exactly the procedure you have to follow when offroading in the tacoma! Now in its defense it works pretty well but sometimes I felt like I was preparing for flight!

 

I have a 2013 2x4 Prerunner. I wanted to know what mode if best for driving in heavy snow with chains/cables on your tires.

Also why would you ever want to have "open differentials"

Sorry if this was already covered, I only got through the first 25 pages. Great thread!

 

Hi Orion (The Hunter),

The only time you would select VSC OFF MODE (open differentials without traction control) is to let the tire(s) spin freely to clean off the tread from snow or mud or to act like a goofball and spin around. Having open differentials, as all Tacomas have (except '05-'08 Sports, in the rear), makes steering easy and less mechanical problems.

This is why Low 4WD without A-TRAC is so 'weak' compared to High Range 4WD with TRAC ON. I can climb a grade further in H4 (normal TRAC ON mode) than L4 with A-TRAC Off.

The non-Off Road TRD 4WD Tacomas do so much better after performing the 4-Low Trac Mod, to fool the truck so TRAC works for them in L4. Those of us with the Off Road TRD should push the A-TRAC button and always have A-TRAC on standby when you go into Low Range.

As for your first question... the standard mode in H2 and H4 (TRAC ON) is best for almost all driving. In L4, have A-TRAC on standby by pressing the button when you go into L4, and it will always be on standby until you push it again.

The only times to use AUTO LSD is if you don't want to use 4WD... to move from a stop should one tire spin... and if you are in snow or mud:
H4 is better than H2 with AUTO LSD to get moving.
H2 with AUTO LSD is better than H2 with TRAC to get moving... as AUTO LSD is TRAC, but without engine output regulation.

In H4, TRAC already is free of the regulation (2009-2011), so it is like AUTO LSD, but on all 4 tires... Now, we had some discussion about some changes made in 2012, which (if I recall correctly) changed the wording of the modes in H4.

 

He has a Prerunner

 

Actually, the having 9 modes (or 10 now?) all controlled by a dial or buttons is more entertaining than necessity.

For nearly every condition, no buttons are touched in H2 or H4, and in L4 only the A-TRAC button needs to be touched ONCE, and never again (unless it gets pushed on accident or you disconnect the battery).

TRAC works great, specially in 4WD... as I have proved (at least to myself) when I compared to my 2005 Tacoma in the same places. TRAC took me places that required either deflating tires before, or low range before.

A-TRAC is simply amazing as it has taken me all the places that I previously needed a locker for, and more... out of places I would have needed a buddy with a tow strap or winch to pull me out! I have never been stuck with the A-TRAC Tacoma... and I have tried many times (it's fun trying)... You may have seen the video of me easily pulling another truck up the Diablo Dropoff... and I have pulled others too, in snow and in dirt, with A-TRAC.

 

OK... then only the 2WD advice applies to him, right? Here is just for the 2WDs:

The only times to use AUTO LSD is to move from a stop should one tire spin... and if you are in snow or mud:

H2 with AUTO LSD is better than H2 with TRAC to get moving... as AUTO LSD is TRAC, but without engine output regulation.

IF you are a 2WD OFF ROAD, then the rear locker beats AUTO LSD!

 

Yep