Mods - ATRAC & Locking rear dif in other than 4L
- Thread starter LWN
- Start date
Jeremy556
New member
After reading this novel (again, apparently), I was pissed I couldn't "like" it again.
Gabex35
New member
I looked into it but it was much more involved than the FJ. The "blue" box seems to be under the dash near the glove box. I didn't feel like taking things apart without a good grasp of how to mod it right.
serial0l0
New member
I may have misread the OPs experience, but I think if you do it without the switch you will be constantly dealing with a CEL. I think he said if he forgets to throw the switch before he turns off the truck it throws one. That may not be a concern tho.
Good question on the multi-terrain. I don't know if it was an option on the OPs year model. Do it and let us know!
edit:// Cancel that. Multi-terrain was there on the 2010! Sorry.
Good question on the multi-terrain. I don't know if it was an option on the OPs year model. Do it and let us know!
edit:// Cancel that. Multi-terrain was there on the 2010! Sorry.
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Engineer
New member
I would assume so but maybe someone else can confirm. I had my dash all apart a few weeks ago and spent an hour taking photos/confirming the wiring on my 2014.
Does anyone know why the 4runner seems to have a different 4x4 control system then the FJ. From what I understand the FJ has a 4x4 ECU and a Rear Dif Lock ECU where the 4runner it seems they have combined those units into the 4x4 ECU.
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TheWraith
New member
No it didn't throw a cell ... the original poster just added a switch as a safety precaution for idiots driving his truck and flipping the diff lock on at hi speed.I may have misread the OPs experience, but I think if you do it without the switch you will be constantly dealing with a CEL. I think he said if he forgets to throw the switch before he turns off the truck it throws one. That may not be a concern tho.
Good question on the multi-terrain. I don't know if it was an option on the OPs year model. Do it and let us know!
edit:// Cancel that. Multi-terrain was there on the 2010! Sorry.
Basically the wire does what the sensor in 4L does. Grounds it. Sooo basically by passing the 4L sensor switch...
I'll do this next week and post what happens
serial0l0
New member
Yep, sorry. I just meant a check engine light. If he turned his truck off with the switch still on he said it caused a CEL that eventually went away. I'm guessing if there is no switch it is always grounded hence possibly causing a check engine light. I haven't done this yet and may not so it is just an assumption.
Look forward to hearing your results. Finally a mod I'm not too stupid or lazy to do and I'm not sure I need it.
Thanks for the up close pics Engineer.
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TheWraith
New member
Yep, sorry. I just meant a check engine light. If he turned his truck off with the switch still on he said it caused a CEL that eventually went away. I'm guessing if there is no switch it is always grounded hence possibly causing a check engine light. I haven't done this yet and may not so it is just an assumption.
Look forward to hearing your results. Finally a mod I'm not too stupid or lazy to do and I'm not sure I need it.
Thanks for the up close pics Engineer.
Gotcha ... I'll just have to remember to not leave the switch on during start up or shutdown. I just think having a second button redundant.
I'm going to try in next time I have a couple of days off in a row.
let you guys know about the multi terrain
LWN
Member
After using this mod for several years, my only complaint is that it will occasionally throw a check engine light. It seems to happen when I exceed a speed threshold while in 4H with the mod engaged to trick the truck into thinking I'm in 4L, and it happens regardless of whether ATRAC or the rear locker are engaged at the time. But it doesn't affect performance and after a short while, the light resets by itself and turns off.
LWN
Member
I'll offer a counter opinion on this modification and some of the discussion I've read to this point (starting w/ the latter)....
W/ regards to engaging A-TRAC at higher speeds and possibly causing damage or control losses - you won't. That's not how A-TRAC works and I think some people are confusing the functionality of A-TRAC w/ TRAC / VSC. When you feel wheel spin in 4Hi and you bog it isn't because of braking - its because the ignition is getting cut by the computer.
The braking applied to the wheels to direct power to the other wheel on the axle in A-TRAC mode is minor and is not at all equivalent to riding the brakes or using an e-brake to distribute power. You are not loading the drivetrain, no more than driving a vehicle w/ an old fashioned LSD w/ clutch packs is loading the drivetrain. The clutch's in a LSD diff don't provide any noticeable drag to the drivetrain - they provide just enough drag to the wheel that is spinning so that power is diverted to the wheel w/ traction. There is ZERO attempt to stop wheel spin - just to balance it across the axle.
A-TRAC works exactly the same way, but instead of using clutches, it uses the vehicles brakes which are much easier and cheaper to service - very cool system! A-TRAC also works better than any LSD that I'm aware of, providing tighter balance of wheel spin across the axle. Again there is ZERO attempt to stop wheelspin, A-TRAC balances it across the axle. If you can't get grip with either tire, the tires will spin (vigorously). This will NOT cause any drivetrain damage in and of itself.
Vigorously spinning the tires does have the potential to overheat the system if done long enough and vigorously enough. I've done this spinning up a wet rocky mountain slope in my Tacoma. A-TRAC was doing a spectacular job pulling the truck up through the rocks w/o the rear e-locker and I was getting a little to joyful and exuberant w/ my throttle. The A-TRAC light flashes when the system is overheated and A-TRAC disengages. About 2 minutes of cool down and everything was fine. I continued on w/ more sensible throttle input and never had the problem re-occur.
With regards to the e-locker and use at higher speeds, this is the same e-locker that Toyota puts in their Tacoma Pre-Runner TRD OR models. These are two wheel drive trucks w/o a low range. My opinion on the reason that Toyota does not make the locker available except in 4L on the 4wd platforms is not because of safety or handling, but rather perceived use. They expect that if you are using the locker you are in a serious traction problem and will be in 4L.
Now for my opinion on performing these mods to my vehicles - I have no use for them. In loose traction conditions like mud, sand and snow (off road), 4Lo will easily drive the vehicle in speeds in excess of 20mph w/o over working the motor/drive train. I just don't believe that wheel spin across an axle is a significant problem at speeds above 20mph - you are not experiencing wheel stoppage at those kind of speeds, LSD/Locked Diff is not going to help you (and you are significantly increasing the potential to break something w/ the locker). For situations where the traction advantage of A-TRAC/locker is needed you should be in low range.
I know what's coming next - those who have performed this modification swearing I don't know what I'm talking about! It makes a huge difference driving in sloppy mud/sand at higher speeds. I don't doubt these experiences are true, just not for the reasons you think. When you trick the computer into believing it is in 4Lo it de-activates the traction control and VSC. Now your throttle won't cut out on you when you slide or the wheels spin while you are in 4Hi and the performance improvement is immediate and very noticeable.
Only problem is you can achieve the exact same thing by pressing and holding the Trac Off button for 5 seconds while stopped. Lots of people don't realize that you have to press and hold in order to shut the VSC off, so consequently, every time the vehicle slides it cuts the ignition and bogs the motor.
In conclusion - Modifying A-TRAC to work in 4Hi won't increase potential to damage to your system. Modifying e-locker to work in 4Hi won't damage system in and of itself, but higher speed operation does increase potential for damage with any locker, regardless of gear range in use. Despite the fact that there is little increased damage potential, I don't see any performance gains to making this modification. Toyota has thought the systems through pretty well and they work well.
David
Thanks for the response and detailed overview David. Every time I go off-road the first thing I do is disable traction control by holding the TRAC button as you described, but for me personally, that's not really my issue in mud. 4L just doesn't give me the pull and wheel spin I need for the gummy stuff - I've tried mud in both 4L and 4H with traction control off and there's no comparison, at least in my experience.
When the going has gotten really muddy, this mod has saved my bacon several times. For folks in steep rocky terrain I can see where 4L is the only option so this mod is probably irrelevant, but for folks like me that deal with flat muddy terrain, it's a big help, in my experience.
e60ral
Banned
it seems like it should be pretty easy to ground a wire in the field if you needed to
L.C.
New member
Was this using a switch or directly grounding?
TheWraith
New member
Direct ground
L.C.
New member
Do you think that may have something to do with it?
I think it was mentioned before that if the wire was grounded when you turn the ignition on it may throw a CEL or other code. Could you try a switch and see if grounding once the truck is running still yields the same result?
This is a bit discouraging since I was looking forward to doing this mod. I'd really like to know if this mod allows you to lock the rear diff in 2WD only since that's the goal for me.
Puddingpants
New member
I was wondering if you ever got this to work?
I didn't care for locking the rear diff in 4HI, but I wanted to use this to activate KDSS in 4HI.
Coming from a Jeep Rubicon where I could disconnect the front sway bar in 4HI, it bugs me I have to be in 4LO to let the sways loose in the 4Runner.
