DIY ADD Actuator ECU

How do these things work from factory? Specifically, what causes them to stop?
Do we think there's a current sensor similar to the auto-up window switch? Or is it just timed?

Attached is what I have on the subject...





Also... what purpose does the vacuum port serve?

 

So I don't pretend to understand the wizardry of electricity and can't help you with the electronic portion of your question. Regarding the vacuum ports (should be 2 of them), they're supposed to physically move the actuator in and out of 4WD. You should see two vacuum solenoids on the inner part of the driver side fender well (behind the battery) that have vacuum lines running down to the add actuator. My understanding is that the 4WD ECU controls a VSV that allows the correct solenoid (one for engagement, one for disengagement of 4WD) to pull vacuum.

I actually got my 4WD working on a '98 4Runner, with the same 4WD system, by hooking up a handheld vacuum pump to one of the vacuum ports and sucking the actuator into 4WD. That freed up the previously stuck actuator, and the vacuum solenoids were then able to engage/disengage the actuator properly when the 4WD selector switch in the cab was pressed.

 

Hmm so they way you say it sounds like it's not an electric actuator at all, but switching power to VSVs which activate vacuum one way or another. I'll have to take another run at the diagrams with that in mind.

 

Precisely. But note that at some point it changed over to electronic ADD actuator, and vacuum portion was dropped.

For example my '03 Tacoma has electronic ADD, but my '98 4Runner and three friends' Tacomas ('98, '99, and '00) are all vacuum operated. So I'm guessing the switch took place as part of the '01 face-lift, but I'm not positive that's when they switched it.

 

Your FSM clips are about the "1 touch 4wd" AKA bush button transfer case as opposed to the manual or "J shift case. At the end it describes the electric version of the ADD actuator (later years).
Confusion sometimes comes up because the electric ADD actuators have a vent or breather hose that looks like a vacuum line but it's just a vent. The vacuum ADD actuators have the two VSVs on the fender well with two vac lines going down to the actuator.

 

Just to clarify, one can have a push button T-case with a vacuum operated ADD, or vice versa, a J-shift with an electronic ADD. So the type of Tcase is not predictive of the type of ADD actuator.

 

You have it correct.

 

Ok, then I think that confirms I have the electric type. I have a J-shift transfer and an electric ADD front diff. Need to make something to control it.

It would seem to me based on the last image that 1-2 contains the solenoid coil that moves back and forth depending on polarity. 4 is ground, and 3 is +B (which seems to do nothing directly), so what the heck do 5 and 6 normally do?
Actually I'm not even certain I have 1-2 correct since you would think you only need to connect 4 to ground and either 1 or 2 to +12V in that circumstance.

 

You need to make something to control the ADD? As in, it’s not engaging properly when you shift the transfer case? For the j-shift case with ADD, there is a relay (called a Transmission Control Relay), which signals the ADD to shift when the 4wd switch in the transfer case is engaged. Perhaps the switch is bad? Or I’m not understanding the issue.

The wiring diagram you have above is for a VF3 transfer case, which is the part time 4wd (basically AWD) transfer case from a 4runner. I’ll have to look at the diagrams I have for our setup later, but you’ll want the one for a VF2 transfer case. Also, if you have a j-shift case you don’t have a 4wd ECU, that is only for the push button cases. J-shift uses a relay only.

 

I'm finishing a 4x4 conversion of frankensteined parts. I do not have the 4WD ECU to control the e-ADD

 

Are you using a J-shift t tcase? As @drr mentioned J-shift cases use just a relay. So maybe you can make that work

 

Yes.
I'm basically asking if anyone has a true pinout or wiring diagram for the ADD actuator plug (6 pin).
A relay isn't able to be bi-directional on its own, and my guess is current shouldn't be constant

 

I can check my FSM for my '03 Tacoma tonight when I get home and see if it's got that info. My truck has the J-shift + electronic ADD, so I can also snap some pics of the connectors on the Tcase and ADD actuator if you think that'll shed any light on things

 

See if you can find anything in your FSM, but I don't think pics will tell me any more than the 2nd pic. Appreciate it

 

Check out this thread. I created a pinout description with the plug diagrams and attached it somewhere in that thread.

You’ll need the transmission control relay mentioned in there, and will need to create a harness to go from the transfer case switches to the relay to the ADD actuator.

https://www.tacomaworld.com/threads/2-4-select-to-j-shift-conversion-help.808308/#post-29369605

 

This is exactly what I needed, thanks!

Now the question of exactly what's going on with those limit switches. Are they triggered by (within) the ADD actuator reaching their full extents? If that's the case, I can simply buy another window switch and wire in a PMOS in series with each direction, with the gates tied to the limit switches and I'm done

 

The only limit switch is within the ADD actuator you already have - once the limit switch sees that the actuator has successfully traveled the full throw (i.e. completely engaged the stub shaft in the diff) it signals the dash light which lights up.
I don’t see any need to add any other hardware? Unless you want to use that signal to trigger something else.

 

I don't think you understand my setup. I have nothing that can control this currently. I need to power the actuator both forward and backward to engage/disengage on demand. There will be no tie to my dash as that circuitry does not exist, so I have to make it.
Since there are seemingly two travel switches, I'm assuming one triggers once one direction is reached, and vice versa, and neither are active when it is moving. So I need to monitor all that so that when I manually move the actuator (with a separate switch for example), I (or a microcontroller) knows when to let go.

 

Ok this looks a lot more complicated on paper than it is lol

 

This is a 2nd gen ADD but the 1st gen is nearly identical.
You have 2 limit switches (DL1 & DL2) and a detection switch (ADD), DL1 tells the 4wd ECU when the ADD Actuator has reached the end of travel to the Locked position and DL2 is the end of travel to the Unlocked position.

The ADD switch is the physical position of the shift fork (closed in the locked position and open in the unlocked position), a spring loaded "wait" mechanism allows the actuator to move to it's limit and the spring will pull the shift fork over once the dogs on the shift collar line up in the axle.