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

Nice job!

 

Got a question for you David:

It's been raining pretty good the past few day. So, I decided to try out some of these settings. I was just messing around with the 2WD settings. Unfortunately, I couldn't really get the "Open-Diff" to go. I could click the VSC button and get the "Auto LSD" to engage. However, if I clicked again, it would just turn off (that includes pressing and holding). On the other hand, if I pressed and held from the beginning, it would just go to "Auto LSD" like before. So, what am I missing?

I noticed that there were 2 lights that came on: "Auto LSD" and another one (maybe ABS?). If I pressed and held, they would both turn on, just like when just clicking the button; however, if I tried to goose it, the ABS? light would turn off.

No matter what lights I had displayed, it ALWAYS felt like both rear wheels were breaking loose when I layed into it.

What am I doing wrong or am I just missunderstanding what the lights mean?

 

It is good that you are 'playing' with your Tacoma! They should be fun to operate, naturally!

I must tell you I first had the same problem... only when I was in H4... I couldn't seem to make it go to open differentials (VSC OFF MODE). If you read my posts from last December right after I got my truck, you will read almost the same things you are writing.

Good people here helped me... and I made it a personal mission to continue to help others with their 9 driving modes... (those with a 2009 or newer 4WD Off Road TRD).

Here is the chart on using the VSC OFF switch... note the light and dark arrows...



To go from 'normal' *or* the TRAC OFF (AUTO LSD) mode to VSC OFF MODE / Open Differential(s) follow the dark arrow and the instruction to press and HOLD the switch (while stopped) for 3 seconds.

Now, I count more than 3 seconds... but maybe I count fast... seems like 5 seconds to me!

So, while you CAN go into AUTO LSD while driving, you must STOP and then HOLD in the switch to turn off TRAC and VSC.

The Auto LSD (TRAC OFF) Mode can shut off if vehicle speed increases and the Open Differential (VSC OFF) Mode will go back to Normal Mode if your truck is going out of control.

Try it again... be totally stopped and just hold down the button for several seconds in H2 or H4 and see all the lights come on telling you VSC is off, etc. A quick press of the button will put you back in Normal mode or next time you start your truck, you will be in Normal mode.

In 2WD (3 modes):
*Normal Mode (TRAC & VSC) There IS engine output regulation in H2 TRAC.
*TRAC OFF Mode (AUTO LSD) There is NO engine output regulation.
*VSC OFF Mode (TRAC & VSC are both off) Open Differential.

In 4WD High Range (2 modes):
*Normal Mode (TRAC & VSC) There is NO engine output regulation in H4 TRAC.
*VSC OFF Mode (TRAC & VSC are both off) Open Differentials.

In 4WD Low Range (4 modes):
*Normal Mode is VSC and TRAC both off (Open Differentials).
*Rear Differential Locked (max. 5 mph recommended)
*Active Traction Control (A-TRAC)
*Rear Differential Locked + A-TRAC (up to 3 mph).

Here is another chart...

 

Thanks David. I'm a bit embarrassed. I didn't even think to stop my truck to get it to open differential.

I'll try that today.

 

No worries Barron! Just like trying to go into L4 while in PARK, even though the book says NEUTRAL... The brain sometimes doesn't see what is right there! Have fun today!

 

Of all the threads read on here this is the best and most informative for me yet! Thanks both of you for a truely awesome experience and a true understanding now as to why i couldn't get things to work right for me. You guys rock!

 

So how about 2wd trucks with just the locking rear diff, only time i use it is when I go to the forest but when I do I stop push the button let every thing activate and then proceed. I think I have gone 20-25mph with it on no problems

 

That is very rewarding to hear... thanks for letting me know!

The traction control mystery is what brought me here (TW) to ask... others helped me, and I learned then went out in 4WD and learned more... A-TRAC is way too under-rated for what it does!

 

This thread is about the traction controls on 2009 and newer 4WD Off Road TRD Tacomas. Use the search and find hundreds of posts just on the rear locking differential. I don't own a 2WD Tacoma, so I can't advise you as well as others with Off Road Pre-Runner 4x2's. Our rear locker only works in L4 unless we do the relay mod. Top speed recommended by Toyota is 5 mph... top speed in L4 is not much over 30! When you are locked, steering is more difficult since the two back tires cannot rotate at different speeds, as required when turning. Don't use it if you are not stuck or need to climb something!

 

I can now say that I have put my truck through its paces from recent trips to the Sierras and the Inyos. I love my truck. On our trip to the Inyos with 6 other vehicles we had a 4runner which was towing an off road trailer and the locker failed. An FJ with all the same stuff our Tacomas have towed the 4runner out of the tough section. Although I miss my 1st gen I'm more than happy with the improvements Toyota put into the 09+Tacomas.

 

Yah man... and I was saying the rear locker is still offered if the A-TRAC ever fails... LOL.

Thanks for the comment!

 

Nice to have everything regarding our 4X4 options in a concise, easy readable post.

Thanks again,
Scott

 

You are welcome... glad you liked it... and welcome to TW!

 

Very,Very good post,thank you very much

 

It is the least I can do for all the entertainment Tacoma World gives me!

Today, it is drizzling wet in San Diego County, so I punch it at turns from a stop light/ sign... Just the standard TRAC limited slip in H2 (with engine output regulation)... The outside tire spins, but for a limited amount and then the TRAC & VSC engage... (VSC light blinks). I move forward much sooner and straighter than my 2005 open differential Tacoma did in the same conditions... The 2005 would spin out and not stop spinning the low traction tire until I let off the gas... also the '05 would super-over-steer and I could spin-out 180º. The '10 VSC is like having the truck in 4WD on wet pavement... it corrects the over-steer and I go straight... The TRAC keeps me accelerating from a stop after a brief spin-out of the rear tire(s).

 

OK - question for you guys. I know this is really a TRD OR thread with all the talk about A-TRAC. I have a TRD Sport - but a lot of this is useful info for Sport owners also. David K has done a really good job of explaining all the different levels of traction that are available to us. I can really see why the TRD OR's are really much better for off-road due to the A-TRAC. I don't do any off-roading -so I went for the Sport (yes, I admit I like the hood scoop and color matched bumpers,mirrors, etc...) Here is my question though - what is the rationale of disabling TRAC when switching to 4LO? I understand the OR guys can go to A-TRAC in 4LO - but those of us with the Sport and non-TRD 4x4s have open diffs when in 4LO. Is there a good reason why TRAC wouldn't work - or shouldn't be used in 4LO? I know there is a mod to make TRAC available in 4LO - but why wouldn't Toyota have made it normal for TRAC to be on in 4LO? What would be the situation you would use 4LO (without TRAC or A-TRAC) - hard pulling when you have plenty of traction? If I would get stuck in deep snow or mud while in 4HI with TRAC - switching to 4LO with open diffs wouldn't really help me out too much.

 

Additionally, TRAC affects your power output. You wouldn't want that power regulation in 4L.

However, I can see where Auto-LSD would be extremely useful in 4L. Particularly when on uneven terrain.

 

Thanks guys. Yeah - I thought that TRAC would not regulate power output in 4HI. The way David K has explained it is that TRAC in 4HI is like having limited slip on both the front and rear axles. A-TRAC in 4LO is more like having a locker on the front and rear axles - allows much less slipping before brakes stop the wheel. Seems like A-TRAC in 4LO would overheat the brakes quicker than TRAC in 4LO. Just wonder why Toyota didn't give us the option to either have TRAC on in 4LO or turn it off. I'm not that worried about it - since I don't do any off-roading I'd probably never need it.

 

Thank you for your reply and nice words...

First off, traction control of any kind is superior in off roading with maybe the exception of snow.

Spinning tires (in dry weather) causes damage to roads and terrain...

Having total traction as you drive over dirt roads (4WD, limited slip, lockers) is the least damaging and will get you there nice and calm-like.

Some of us want to play like Robby Gordon in Baja and spin away and kick up dirt ('clean tires')... but that is non-productive to moving you forward.

Every rotation of your tire that has no traction (ie. spins), doesn't move you forward.
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Why no traction control in LOW RANGE (except for Off Road TRDs)?

Then there would be little to make the Off Road vehicle different than a Sport TRD. If you want maximum traction (A-TRAC and Rear Locker), you need the Off Road TRD.

TRAC in H4 is great and probably better than L4 with open differentials. One of my early tests between the 9 drive modes we with Off Road TRDs have, showed that I could far out-climb my truck in L4 (open) when I went into H4 (TRAC)... The traction control/ limited slip out climbed the more powerful torque of low range.

As soon as I turned on A-TRAC in L4 and did the climb again... I went as high as I did in H4, if not just a bit more.

So, those of you with a Sport or SR-5/ Base 4WD, stay in H4 with TRAC on for the maximum climbing or traction ability. Otherwise, you could do the 4-LO TRAC (Yellow Wire) Mod. that so many have raved about.

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I have driven many miles in LOW RANGE with A-TRAC on... no over-heating, no problems. The truck is an open differential vehicle most of the time (for easy steering).. the brakes do not work until one tire begins to spin faster than the other on that axle... A-TRAC will slow the spin down to match the opposite traction tire's rotation... so they both rotate at nearly, (if not the same rate), balancing torque 50/50 ... exactly what a locker does. A-TRAC slows or halts the spin quickly, TRAC does it a bit more gradually and not nearly a 50/50 torque balance... but it is good and a whole lot better than open differentials!

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The only benefit to turning TRAC OFF is to stop the occaisional beeping VSC warning when you slide around in sand/ mud/ snow... but then you lose traction... I would rather hear the beep beep beep than lose traction.

I have yet to test the new truck in snow...

On rainy roads, taking off from a stop, I do enjoy the AUTO LSD in 2WD for fun... like Posi-traction... no engine regulation and both tires have power, VSC is off until you reach 30 mph. TRAC is very close in 2WD, but it does regulate the engine and VSC beep beep beep.

Not sure why they didn't make TRAC in H4 also with the VSC off until 30 mph (or more)?

Anyway, thank for the questions and keep 'em coming... we are all learning!

 

True, I guess I thought he was asking why the TRAC we have in 2wd isn't available in 4L. And my comment about ALSD in 4L is pretty well answered by what David had said, pertaining to Toyota offering different options. ALSD in 4L for none OR models would severely affect their OR sales.