3rd Gen Multi-Function 4WD ECU Spoofer

Gotta convince the 4wd ECU and skid control ECU that you’re in 4wd to get the function.

Yes, ARB would be an option for locking diff. Eaton also for a more simple electric locker compared to stock. I don’t even really have the computers that much, I just don’t like the delay of the ADD and think that part is unnecessary. Full manual is ideal though.

 

It’s really not bad at all. The only reason I’m going down the road I am with the multifunction box is because I’ve seen so many threads and so many comments asking for a plug and play option for each of the mods I first posted and I am happy to pitch in with anything I’ve learned to help someone DIY the crap out of these things. It gets a bit more complex trying to emulate multiple things rather than a single thing like you’ll do, especially the transfer case.

I would personally shy away from tying the relay coil ground through the 4wd mode select knob and go for a high impedance solution (like the design of the boards I previously linked) to prevent issues with the 4wd ECU or the wiring between the switch and it, but whatever works is cool.

Two tips I’ll throw in for the resistors to emulate the motors:

The original 2LM design used a large heatsink type resistor, and while I’m all about over engineering things, I do not believe that type of resistor is necessary and the primary reason for that is the 4WD ECU stops pushing power to the actuator motor when the limit switch is activated. You’ll be throwing the fake limit switch with the relay at the same time that it’s trying to send power to the motor, so it’s a fraction of a second that power will flow through the resistor and it will not have time to build up significant heat. Therefore, I believe a normal axial resistor should work fine. I have specked a radial resistor with a heat tab for the board in case I need to dissipate heat for a more prolonged sequence, but that’s still substantially cheaper than the big heat sink type resistors that were previously used.

Additionally, based on the factory service manual, the 4wd ECU is measuring the actuator motor for a maximum current of 25A but it also lists the nominal resistance range as between 1.5 and 10 ohms. Resistors capable of high current and low resistance tend to be pretty expensive, so I’ve chosen to use two parallel resistors of 18 ohms, which will equal a 9ohm circuit and meets factory spec, and each resistor specked to handle at least 1.5A or more, which is well beyond the current for each resistor tied directly between upper nominal IG voltage and ground.

I will be testing this setup extensively, but I believe it will be way beyond sufficient, and I’d recommend you do the same for cost efficiency if you’d like to go that route.

 

I’ve read through all this and am getting kinda lost.
Is there an easy way to just fool the computer to allow multi trac and locker in 4hi? I think it’s super dumb that this shit doesn’t work in 4hi. Mud in low range =stuck.

 

@dumprat Easy? Depends on your knowledge of electronics. I’ll break it down to two sections for you:

For rear locker, the mod you’d want is anytime lock. You’ll need to hack up your wiring harness and use a pwm controller to engage it.

MTS would require you to spoof that the truck is in 4Lo, which is more involved. You’d have to bypass the tcase actuator motor to a resistor so that it didn’t move as well as spoof the correct combo of open and closed limit switches. Much more difficult, especially if you don’t use a microcontroller. Additionally, I don’t believe that MTS is valuable outside of 4Lo because I believe it would be programmed for wheel speeds associated with 4Lo, however I’m not aware of anyone giving it a test run. I’d actually think that the standard TRAC in 4Hi would be better and then add anytime lock to give yourself at least 3 powered wheels, plus TRAC would be braking to transfer the front power between left and right.

The easiest solution will definitely be to wait until I get my board & box manufactured because it will be plug and play for you.

 

Well I’ve got great news! The ADD itself is stupid easy to spoof. You need a relay, and a resistor. I had 2 diodes installed (for
tying DL2 and ADD together) for testing but they are not needed - I removed them after to test again and confirmed no need for them. It is as easy as expected, you basically use a resistor to spoof the motor, and a relay to switch back and forth to tell the computer the limit switches are at their limit. Sitting still, 4x4 engages INSTANTLY at the transfer case. Less than a second per shift. This makes sense, since the ADD is the one that has to get everything lined up before shifting.

No error codes, everything just works.

I bought a new 2 lo harness and hacked it up for testing. I’ll clean it up and get all the wires to the lengths I actually want now that I know it will work.

Waiting on my FJ diff tube from Sparks Parts (parts are ordered from the warehouse and expected to ship any day now). I bought a dummy plug for the old ADD connector so I can cap the circuits off nice and clean from the elements.

All wiring for this will be done at the 4wd ECU connectors since everything needed is there. I could do it at the ADD but would need a power and 4x4 signal ran through the firewall since those don’t exist at the ADD.

Hope this helps @tcmd in his module development now that we know for sure what will fool the ECU as far as ADD spoofing goes

I’ll do a project write up for the whole thing elsewhere once done and quit clogging up this thread about ADD specific stuff.

 

Very, very nice work!!

 

Any updates here?

 

So I’ve been able to prototype the electronics and everything is working great!

I’m having trouble finalizing my plans for the box build. I would be super thrilled to find PCB mount connectors for both the 40 and 10 pin connectors, and all that I’ve found so far is the 40 pin in either female or male (can’t recall which) and I would want the other gender or both, depending on which direction I go with this. I haven’t found the 10 pin at all in a PCB mount. With all of that said, I have successfully crimped pins onto solid copper to make a prototype of making my own through hole connector, and that worked quite well for the 10 pin, but the 40 pin is a nightmare due to the minor bends in the solid wire, so I’m trying to come up with a process for terminating them after the wire is already in the hole.

Another thought I’m having is to make the box more of an open concept so that anyone with the know-how could make their own configuration of electronics inside if the decide they have some other mod they want to make. In that scenario, I’d sell the box with the connectors and they would terminate to Zif connectors for easy connector to board interfacing. This design also helps me to be able to break out the mods I’ve designed into separate modules to be able to sell them separately, which would be cheaper for the buyer, and doesn’t leave a bunch of empty holes on a single big PCB where components would be left off, like I was planning in my original design.

I would be happy to take input on any of these things, and I’m just trying to keep moving forward as I encounter obstacles.

 

It's been a long time, but I believe this thread is about making something for the 4X4 ECU. If so, just open the ECU and look very carefully for part numbers on the existing PCB connectors. My bet is you will find some, and who makes them (mostly Sumitomo and another company I can't remember right now); what is not a certainty is if they can be released to anyone but Toyota or their partner Aisin.
I've had my 4x4 ECU open and it is easy to do.

I just found a picture of my open ECU and both the 40 & 10 pin connectors are all one piece - very custom made for Toyota/Aisin. Part number 2950080041, see no manufacturer mark in my picture. There are five other possible views of the connector that I do not have.

 

Might ask the 2Lo kit developer where his builder gets his connectors from. I couldn’t find them myself but never bothered to ask, for all my custom experimenting I kept buying 2L kits to hack up, which is of course not very financially feasible.

 

I have the cable mount connectors that they use on those kits, so that’s not a problem. I need board mount connectors.

 

Bump!