Rear Diff Lock Anytime Mod 3rd Gen DEVELOPMENT

I put some double wall heat shrink and loom on it to snug the fit up but it was a bit much as far as added thickness so it doesn’t quite slip in now, but thought I would try it out before fiddling with it more. As it sits it actually points directly at the driver’s position though, so happy little accident there.

 

I reordered the harnesses this morning - the anytime diff lock in first, 2-lo in second.
4-hi/lo functioned normally.
2-lo seems to be functioning, i forced, and received the error message when rolling the dial back to 2 wd with the button still pressed.
Anytime diff lock seems to be working as well. LED lit up, traction control turned off.

It looks like these two products work together if connected in the right order (tho I freely admit there could be some installer error involved).

 

That is interesting, I have mine in the order you initially tried and it’s fine. Maybe a connection didn’t quite seat or something.

 

Installer error for the win! I'm just happy they work together!

 

Agreed, they will be a handy duo - very glad people figured these things out!

 

Mine showed up and I got it installed without tapping into the traction control wire. Everything functions as it should, just have to turn off traction control with the button. I don't really understand why the wire to tap into traction is even included. That seems to be most people's hang up with this kit. Should be stated its optional on the site, I imagine alot more people would buy knowing that info.

 

Mine also seems to work with traction control left on, but I've not used it a lot yet - does this eventually cause something to go off the rails?

 

Another thing is, at least on mine, I was able to snake my arm back behind everything, pop the blank out and install the switch/wire without having to remove the console.

 

I imagine if you have a trac on it could cause some issues if the brakes fight the locker. Though if your rear diff is locked a trac shouldn't be trying to assist the rear anyway. I'll only use mine with the traction control system completely shut off regardless. I just really don't like tapping into wires that are a pain in the ass to replace if they get messed up.

 

Well the times I have had it on for more than a second without TC off has been in 4HI, so A-Trac wasn't an issue there since it's 4LO only (isn't it?); and as I recall, 4LO turns TC off, does it not?

 

4 lo turns off everything including abs. A trac comes on with a short press of the tc button and you still have vsc on I believe. If you long hold the tc button it turns off trac a trac and vsc, abs is on unless your in 4lo. I would just long hold the tc button anytime your using the locker to be safe.

 

Maybe @ExperiMentaltaco wants to chime in as to the reason for tapping into the trac wire?

 

Sometimes...somtimes..............I forget things.

Ultimately I'd like to hear from Mr. Mental as far as what he found that drove the need for tapping that wire before coming to any sort of speculation fueled conclusion. It may also be possible that they're just mimicking what OEM settings are in place when the locker is on and they figured out how to do it, but may not actually know if anything goes haywire if run with TC on..

 

I don't see any reason to run the locker with Tc on.

 

I don't either and I am not trying to for any reason, but I want to know if that wire is there just for convenience, or for the safety of the truck in some form or fashion. I can't think of what it would mess up, but hell hath no wrath like an onboard computer not seeing what it expects.

 

This is my GUESS....
(And they haven't figured out how to easily shut off ABS, which OEM does as well as trac off.. )

 

Here is a view from a vehicle dynamicist. Don't forget we are talking about 2 different systems: VSC (stability control) and TRAC (traction control). My best guess is they just added this VSC/TRAC OFF function to the locker mod because it mimics what happens with the factory system. There's really no great reason to do it and only one specific situation where a locked rear may disrupt the action of the stock control systems.

Traction Control
2wd: In 2wd, the traction control systems (TRAC, autoLSD) are unaffected because these systems operate on rear wheel slip based on cross axle reference (autoLSD) or front axle reference. The corrective action is either individual wheel braking or engine cut. With the locker locked, there is never cross axle slip (both tires will always be rotating same speed) so autoLSD never even triggers. For traction control if one rear wheel slips then they both must be slipping so any corrective action (wheel braking or engine cut) will properly arrest the spin-up at the rear axle.

4wd: Same thing here and since ATRAC and MTS are looking for cross axle slip there will never be any and the system will never trigger. For traction control it's also the same, if the truck detects forward wheel slip (front and rear must be spinning (4wd) and therefore both rears are slipping (rear locked)) then any corrective action (wheel braking, engine cut) will still properly address and arrest the slipping issue as intended.

VSC:
With VSC we are interested in keeping the vehicle under control and on its intended path based on speed and steering angle. In order to do this the vehicle will compare the actual state of the vehicle to the requested state. If there is a large or dangerous discrepancy the vehicle will attempt to correct the issue by cutting engine power or apply individual wheel brakes. The only issue here is if the diff is locked and the vehicle chooses to correct a stability error by applying *individual* braking to one of the rear wheels, then that corrective action may not have the intended effect. This is because applying a single wheel brake to a locked axle is effectively like applying braking to the entire axle and thus has a different effect on the dynamics of a vehicle than applying single wheel braking to a wheel that's coupled to the opposing wheel through an open differential. What the actual implications of this are in the real world with the stock Toyota control system, I don't know. But it's the only possible situation I can come up with where a locked rear could maybe interfere with any factory system.

ABS:
Locked rear should have zero effect and the system should operate like normal.

 

Well put sir, I'll just continue turning off everything before I use the locker.

 

So, who’s gonna go be the mad man who tries to go drifting with the locker and VSC still on? Short of some electrical demon, in my mind the worst that would happen is the ABS computer beating the snot out of the wheel it wants to slow down, and it sounds like someone (more qualified than myself) has the same hunch. And that would basically just be momentarily unless you’re just out doing the aforementioned drifting.

And to re-iterate: this stems from wanting to be aware of potential damage from using this aftermarket system not quite as designed, not because I have some overwhelming desire to have a locked diff with all the systems active; is it just not ideal, or actually risks damage to the truck beyond a clearable error or something like that.

 

And this is the exact reason for the wire tapping into the traction system. To stop some poor uneducated fool from causing the systems to fight each other them blaming the company that made the mod lol. I was just out drifting in the snow we got this morning with everything off. Lots of fun, reminds me of my old truck.