3rd Gen Multi-Function 4WD ECU Spoofer

Hi fellow Taco enthusiasts.

tl;dr - I am developing a spoofing box for the 4WD ECU that can cover the full range of requested features that I’ve discovered in various threads. Please chime in with your thoughts.

Like many of you, I have recently had the misfortune of a failed actuator in my transfer case. In researching how to fix it, I came across many helpful threads here, including info from those who have swapped to an FJ tcase, which led me to all of the different electrical mods that have been made to the 4wd system.

Each of the existing mods have been approached with an electromechanical solution (switches, relays, etc.) which is working well for a lot of people and there’s no necessity to swap what you’ve got. I’ll approach these mods from a microcontroller based system, and largely solid-state electronics, except where switches and relays are obviously and absolutely necessary.

@BigWhiteTRD is an absolute legend for the R&D work he has put into these mods and he has been instrumental in providing me what he has found in techstream and experimentation. Super huge thanks to him for all of that.

In looking through all of the threads, I’ve found that these are the most important & requested features of a box like I would build:

• • Mods are plug and play.

• • Transfer case spoofing (for FJ swap mod, with no truck ignition off & back on)

• • ADD spoofing (for various front axle mods, including 2 Lo mod & ADD delete)

• • 2LM with single button press

• • Anytime rear locker

• • @BigWhiteTRD has also suggested a sort-of “Brute Force” mod to bypass the factory 4WD ECU and force voltage to the transfer case actuator and ADD as needed if the factory system is locked out. This would have a lot of caveats, but the idea is that it gives you a greater chance to drive the truck off a trail and on the highway back home if there’s a simple limit switch failure or actuator motor current leak. Let me know if you like this as a part of a multifunction box or a separate DIY build.

• • Lastly, I’m considering making an add-on digital controller & readout for the box to also act as a troubleshooting tool. The main purpose would be to see the data that is usually pulled from techstream, like limit switch timing, motor current, relay engagement and provide the reason for the dreaded flashing green 4WD indicator. I’m not totally convinced that this is worth development time unless there’s significant interest in it, but it does seem to pair well with the brute force mod idea.

Here’s the best part: I’m almost done developing the whole system. All of my recent spare time has been spent combing through data, reading the service manual, and drawing schematics.

Please chime in with your thoughts and let me know if there’s anything I’ve missed and if you’d like to see this kind of thing available.

 

I will definitely say it's definitely one heck of a first post.

BTW. POST MORE PICTURES.

 

just WHEN ??????????????

 

Wow. If this works out, I am totally in!

 

Very interested.

 

@BigWhiteTRD Ha! I haven't had to do any significant work to my truck and it seemed like every possible question was already answered somewhere in the forum, so I never felt a need to chime in til now! And there's not really anything to post pictures of right now except a box of parts and some schematics that need verifying

@84-4runner If I can get a few people to chime in on the brute force mod & digital controller, I believe I can get PCB sample in the next few weeks and give it a test run. I still need to figure out the enclosure design, which I'll likely do with my 3D printer while I wait for the board samples. I'd say optimistically that it's about 2 months out. I've got factory connectors sourced, so that's a great start and I just need to finalize the custom hardware.

@BLtheP It's gonna work out, I'm determined to make this so that all of us can improve our trucks!

What do yall think about the brute force mod and digital controller? Include on this box or leave it for another box / mod?

 

I use 2wdLo mod quite a bit to back construction trailer up a steep hill. And 4wd in snow. With both, enough lock or unlock misfires that I'd love something crystal clear telling me locking status.

 

So what I’ve always wanted to do is swap to the manual FJ transfer case and delete the ADD. the ADD would be converted to where the front diff has the solid diff tube off a manual FJ cruiser. I do not need or want 2wd so I would rather have a fully live front diff.

the 3 hindrances to me doing this swap with a manual transmission are:

1. back of transmission clearance for the shift rod (grind trans)
2. Losing 4x indicator lights on dash (since the electronic tcase would disappear and the 4wd ECU hands those signals to the combination meter via CAN, so I can’t just wire up the FJ switches)
3. ADD problems - 4wd ECU would be looking for the missing ADD and would throw up plenty of errors.

I’m kind of a stickler about stuff and don’t really want to do swaps unless I can make them about 99% as close to stock as possible. That means maintaining working lights, all features remain, etc. The spoofer harnesses work but they require keeping the tcase knob still in the equation. I’d rather delete the knob entirely and use the air conditioning trim panel from a 2WD (without smart key so no push button hole) if possible.

no need for anytime locker, actually prefer to not have that so I don’t accidentally engage the locker.

brute force I would think should be some sort of add on.

the digital troubleshooting tool would be cool.

 

Whatever you build, make sure it's on the same level, in terms of physical & electronic production quality, as the quietly famous 2nd gen 2LO mod: (https://www.tacomaworld.com/threads/2lo-kit-for-2nd-gens.554456/)

It's no longer being made but pics are here for example & inspiration. Mine continues to work flawlessly, I use it almost daily to back up a steep driveway, and at other times now and then while positioning trailers.

 

I'm taking that as a vote for the digital controller readout

 

Great points there, and it fits right in with my thinking!

So that everyone knows, my design as it stands right now is a single PCB that I can reconfigure with jumpers and only mount the needed components, which should provide the most cost effective solution for each person and their intended purpose.

Ironically, the FJ swap would be the simplest electrical design and therefore the cheapest option.

The main reason I started researching all of this is because I didn't see a great electrical solution for the FJ case swap to keep the truck traction systems happy. The spoofing designs I saw also required the truck to be turned off and back on, which would annoy the hell out of me.

I do have both ADD and tcase emulation in the design, so the truck could completely follow changes based on some input.

Regarding keeping the factory tcase knob in play, I've designed it with the flexibility to keep the factory knob or to insert your own switching source. I may just not be remembering correctly, but I don't remember the FJ case having any electronics to report what mode it's in, but I hope I'm wrong because if it did that would be the easiest way to tie in to my board. I'll take a harder look at that unless someone can just chime in and verify that.

 

FWIW the 2nd Gen 2LO Module I linked/discussed above does not require the truck to be shut off & restarted.

IMO that would be an extreme annoyance, almost a deal-breaker in fact.

 

Good to hear. Sounds like you’re pretty much after what I want in general.

the FJ does have two switches on the tcase, I don’t know how they work. I would assume they are both 2-wire and closed/open report when in one or the other. I would need to check the FJ diagrams for confirmation, but almost 100% guaranteed those switches report position to the FJ 4wd ECU, and then that ECU probably grounds the terminal on the combination meter. Either that or the FJ ECU sends it over CAN like the 3rd gen Tacoma.

If it wasn’t obvious from my post, I would like to delete the knob BECAUSE the FJ case switches started doing all the reporting of what position I’m in for me. So I guess essentially your spoofer would interpret what position my FJ case is in, then it would report that to the 4WD ECU (which would then report over CAN to the combination meter), and then when going from 2hi to 4hi or 4h to 2hi, the spoofer module would be communicating that the ADD operated successfully (even though it’s gone by that point).

 

That is a killer design and definitely what I'm hoping to achieve. I am a bit concerned for now on nailing the design of the plastic box, but with all of the tools we have at our disposal these days, I should be able to figure it out.

 

Oh yeah, I was referring to the spoofing designs for the FJ case. The 2LO mod for 2nd and 3rd gen are quite clever and easy to use. Where I'm aiming to improve the 2LM is taking it to a single switch rather than the current design which is a button press and factory knob turns.

 

Not sure quite how you would get accurate numbers but you might do well to run a market sector analysis & figure out what your TAM (total addressable market) is.

Looks like the guy who made the 2nd gen modules did maybe ?? 2 to 4 production runs of 100 units each, but there is still residual demand for his 2nd gen modules.

I'd guess the 3rd gen market is about as large as 2nd gen, maybe a little smaller, as it spans only 7 years vs 10 years for the 2nd gens.

Maybe figure out your how many you want to make -- say, 1000 units? -- and then cost that out & figure out what is affordable to design/build/market. Also keeping in mind a selling price point. I would guess that $250-$299 is a reasonable sweet spot.

One other thought -- you may not want to make them overly complex / configurable, that could get to be a problem w/ tech support for a too-wide variety of possible setups & use-cases?

 

I totally missed that it had connections when I was looking at it, I must have jumped over that to the existing solutions that ignore them. And I'd bet pretty strongly that it's just switches. Even on our 3rd gen tacos, everything is simple electronics, no CAN data, until it goes from the 4WD ECU back to the main computer, so everything can be tricked with resistors and closing contacts.

 

Check out the attached FJ electrical diagram. This should help.

Keep in mind, the automatic trans FJ has a manual shift part time t-case with the ADD. One of the tcase switches reports that the case is in 4wd, at which point the ECU then engages the ADD. The ECU directly controls the combination meter for the light, it does not appear to be CAN because there is a wire for it. So I imagine the 4wd ECU waits for the ADD to complete its shift, THEN the ECU provides the ground for the combo meter to light the “4wd” light. I don’t think there is any light specifically for 4hi or 4lo. The second switch on the tcase appears to be a neutral switch and ties into the PNP circuit so that you can start the truck with the tcase in neutral and that counts as a neutral. So the transmission could probably still be in gear and still start would be my guess. No experience with FJs so I can’t say for sure.

Manual trans FJ has a full time t-case with no ADD. So on that one I imagine you shift into “locked” center diff and then the ECU grounds
The combination center for the 4lock light or whatever it’s called. Looks like the wire for autos turning on 4wd light or manuals turning on 4lock light end up going to the same pin on the cluster (pin 2 E14 connector), so either they are turning on the same light or there are different clusters between automatic 4x4 and manual 4x4.

 

Yup, really it’s just that CAN communication between the ECU and combo meter that screws everything up. If you can trick the 4wd ECU into believing whatever, then we will finally have these hindrances put to rest.