4WD ECU Spoofer for FJ Transfer Case Install

WARNING:
I have not tested this in my own truck... All data here is my best guess, as tested on 1 truck (not mine) without me being there in person.

So you have installed an FJ transfer case in your 3rd gen (originally 4wd truck). Now you have a bunch of warning lights, (and if you have an OR/Pro you lost use of MTS/ATrac/Crawl/Rear Locker)

Introducing the 4WD ECU Spoofer for FJ... Item not for sale, build your own, come on you already did a giant transfer case mod, you can do this too.

This is the most electrically simple method for spoofing the ECU AND maintain the 4lo operating modes (for the OR/Pro trucks only) that I have found. A more simplified version could probably work if you didnt want to maintain 4lo modes, but this hasnt been tested.

However as I made it electrically simple, it also has a HUGE drawback for USAGE.

You can use your manual FJ transfer case at any time, of course.
To engage or disengage this spoofer (for 4lo modes), the truck ignition has to be OFF!

For example, you leave the spoofer switched Off normally. (The resistors and wiring in the spoofer indicate to the 4wd ECU that the ADD and Transfer case actuators are installed and are in 2Hi). You can use your FJ transfer case manual levers as desired.

To utilize the truck's 4lo goodies. Shut off truck, activate spoofer switch, switch truck to 4lo on rotary dash switch. Start truck. Truck will think it is in 4lo, Rear lock/Atrac/MTS/Crawl will be available. You can use your FJ transfer case as desired.

This mod has been tested by @Bajataco358 using a harness I built. This mod has also been completed by @bravinci . In both cases, (that I am aware of) the mod was done using the 2lo module as a basis. (https://www.tacomaworld.com/threads...-2wd-low-range-for-the-3rd-gen-tacoma.614743/)

To reiterate, this is ONLY useful if you swapped your transfer case and locked out your ADD.

This mod (in this simple form), requires (2) power resistors (1.5-5 ohms), 4pole-double throw relay with 12v coil and a latching switch.






To build this as plug and play installation, I THINK these connectors should work. But if you swapped the transfer case, why would you care about plug and play...
https://www.tacomaworld.com/threads...d-gen-development.537810/page-8#post-18502251
https://www.tacomaworld.com/threads...d-gen-development.537810/page-8#post-18502754


Proof of concept (reused old anytime lock test harness), Note COLORS DO NOT MATCH



I will try to answer any questions. But remember:
I did not test this myself
The value is primarily for people who did the transfer case swap in a OR/Pro truck
This is NOT an elegant mod to Use, its a hideous brute force solution that can be made MUCH better by someone who can do microcontrollers (not me).

[EDIT 12-22-2020, I noticed an error in the relay wiring shown in this thread. Relay pins 9, 10, 11 should be grounded.... Pin 12 does not need ground. Will correct in the next few days]

 

Nicely done! Do you know what the differences would be in a TRD sport? If I lock my ADD I think everything should work as normal, I would just need to jump the 4wd ECU?

 

I am familiar in the wiring of the sport vs OR, and its identical... so I know you could wire the same as this thread.
But the real question really comes down to functionality.

The above wiring design allowed the truck to still use the stock rear locker, MTS/ATRAC in 4lo and abs etc in 2hi.... so it needed a 2hi and 4lo spoof, controlled by a switch (for simplicity).

for the sport, off the top of my head i doubt there is as much advantage in spoofing the 4wd ecu to think it is in 4lo...

So MAYBE you dont need the relay and just hard-wire the 2hi spoof position.... not 100% sure.

Does that make sense? What do you think?

 

I think you're right... I'm not super intuitive when it comes to wiring, but I have people who are so I'm hoping I can get as much information as possible and hopefully they can help me figure it out

 

So do you think you will ever want the 4wd ecu to think the truck is in 4lo?

In the OR/Pro there was a good reason.
In the sport it disables ABS (per my memory). EDIT Note, this statement is WRONG, ABS disable only on rear locker... but TRAC impacts are discussed below.

If you dont want any functionality that the 4wd ECU gives you in 4lo, we can greatly simplify wiring from the schematic above.

Let me know if you want that schematic

 

It does disable ABS but the traction control retains its functionality, which I absolutely want. So far it's been good enough for me to put off lockers for at least a few years. But I'm not positive that the traction control functionality is controlled by the 4wd ecu?

 

From the Deleting ADD system threads, it sounds like a lot of guys are just leaving the ADD and Actuator plugs, and wiring up the dash lights to function properly with the FJ case sensors. And if I'm correct about the traction control functioning separate from the 4wd ecu, I should be able to do the same, and traction control should function as normal...

 

So the 4wd ecu does not control traction control, but the skid control ecu does and relies on status canbus messages from the 4wd ecu.

If 4wd ecu thinks you are in 2hi we can assume you will only have 2wheel traction control. So you will want at least 4hi or 4lo status from the 4wd ecu (as a minimum), So that's a definite requirement.

 

So 2nd gen electrical on the 4wd system isnt ALOT of help for 3rd gen....

Based on what you have said, I can think of a few options that will PROBABLY meet your requirements.

1. Take working ADD and transfer actuators and tie them up under your truck, hook them to the 4wd ecu as per factory, and just let them operate electrically without being attached to the ADD or transfer case. (All traction control and VSC work as expected when you turn the dash 4wd knob). *Recommended solution

2. electrically rig a spoofer that makes the 4wd think it is always in 4hi. (Traction control works as it is intended to work from factory in 4hi...). This is a simple electrical solution. - Edit NOTE, this option is not recommended by me at this time based on discussion in next post.

3. Rig a 2 position spoofer. This solution is described above. Electrically harder than option 2, but not too bad. *Recommended solution

4. Make a microcontroller controlled spoofer. Most ideal solution, that has been discussed numerous times. But doesnt currently exist as far as I know. (Beyond my skill set)... Not recommended within my skill set.

Ask more questions if these options dont make sense. I will help you with 1-3... but you will have to decide which is best and know that I HAVE NOT done this on my own truck....

 

So I have been thinking about your desire/requirement and the traction control modes the team put together at 3rd Gen Traction Control Modes Explained | Tacoma World

So first off, there are some assumptions imbedded in this logic, that have not been verified... I will TRY to identify them as I go where possible.

To have the truck utilize 4wheel traction control, I ASSUME we need the skid control to think it is in 4hi or 4low (not 2hi)... I doubt the Toyota engineers would apply traction control braking to the front wheels in 2hi, so that seems like a reasonable assumption.

Looking at the traction control chart, in 4hi you would have 3 options:
4. 4Hi TRAC ON and VSC ON.
5. 4Hi TRAC OFF and VSC ON.
6. 4Hi TRAC OFF and VSC OFF

So we could make a wiring harness so the truck always thinks it is in 4hi (always, regardless of your transfer case) and you would get those 3 options while driving...

That doesnt look ideal, the most useful option (in my opinion for off-road) of TRAC ON and VSC OFF is not available there, but it is available in 2hi and 4low.

Therefore, I believe option #2 above is NOT recommended (2. electrically rig a spoofer that makes the 4wd think it is always in 4hi. (Traction control works as it is intended to work from factory in 4hi... no abs kill). This is a simple electrical solution.)

Therefore, my best suggestions (with the skillset and items available to us right now) is Option #1 or Option #3.

 

Yes, I agree. I think I'll try option 3 then, since I really want the TRAC ON and VSC OFF.

So I will just need to follow the original diagram posted above for that correct?

 

Yep
[Edit, original post corrected 1-21-21]
(although i do have a typo i noticed in that schematic, that i need to fix properly at some later time... Ground should hook to pin 9 of the relay also, instead of pin 12 which isnt used at all)


Think you are going to try a plug-and-play type installation, or just hack into your harness?

 

I should probably try to do a plug and play, since I'm not positive this will work. Not like I care about being "reversible", but just in case I figure out a different solution, or I screw something up in the wiring, it'll be a bit easier to change.

 

I agree with you, but it is definitely 'hard' to locate the 10 and 40 pin connectors required for P&P.... (because you need a connector that simulates the ECU, and toyota doesnt sell that.)

You will need the 10 pin and 40 pin connectors. The links (to other discussions in the first post) are the best sources I have found for these connectors loose, but I dont know how good availability is now in Covid times...
Another alternative is to use the 2wheel low mod as a source of the connectors, @lapoltba MAY have some extra harnesses on the next batch coming in. You would have to modify the incoming harness. Group Buy - 2LM PnP - Plug and play 2WD low range for the 3rd gen. Tacoma | Tacoma World

Alternatively you could connect elsewhere (near the ADD and Transfer actuators) but i have not investigated these locations specifically.

 

I stopped reading after, "This has not been tested but worked for my buddy's, brother's , sister's, cousin's best friend's, aunt's, neighbor."

 

Good thing for you i put that in the first line then, to save you additional time you could use to write the message above

 

Okay!
Well I'm acquiring parts for the FJ tcase and ADD delete this week, and I have some time off next week so hopefully I'll be able to update you on how it works pretty soon!

I mean someone's gotta do it... and lucky for you I'm being forced into it!

 

Good luck

I built the test harness that @Bajataco358 put into use and tested out for me, but that was an OR.

 

So the links to the connectors in the discussions linked in the original post are broken.. Do you have any other ideas on where to find the connectors? I can't find anything using the google machine..

 

The only source (reliable) that I have been able to find is in Japan. Fair warning, the site is all in Japanese and not the most user friendly.

https://www.hi-1000ec.com/

I will have spares on this batch of 2lo harnesses. I can tell you right now, using that as a starting point is going to save you a hell of a lot of work. It's 50 wires cut to length and 100 crimped terminals just to make the splice harness. That doesn't include any of the other splices or connections you need.