4WD ECU Spoofer for FJ Transfer Case Install

Test Harness has worked perfectly.

Thanks Again!

 

Just for reference, Bajataco358 is my brother's sister's cousin's best friend's aunt's neighbor.

 

So I recently put an FJ case in my 2016 TRD Sport. I found a guy that makes a direct line to the ADD so I can actuate the front diff to the driveshaft by a separate switch. I don't have a locker or a-trac so for right now, I would just like to get my dash back to normal. How would I go about this since I have that extra ADD wiring harness?

 

You will have to be a bit more specific on your exact requirements and I will try to make a suggestion.

Do you just want to stop the dash lights you are enjoying...?
Do you plan to keep truck dash dial on 2hi or 4hi all the time?
Do you want any traction controls (which all 3rd gens have to some extent in 2hi, 4hi, and 4lo)?

You comfortable just hacking on harness, or want to build some sort of plug and play system?

 

I want to stop all the dash lights. Just make the dash in 2hi. I want traction controls. And hacking a harness is fine.
Later I plan on making a kill switch for the abs/traction control for 4Lo so that's on the list after the dash lights are normal. I hope that clarifies a little bit, thanks for reaching out!

 

So if we leave the ECU permanently in 2hi you won't have 4wheel traction control (we think). You would have these 2wd modes available

1. 2Hi TRAC ON and VSC ON
2. 2Hi AUTO LSD. In this mode VSC is off from 0-30mph and on over 30mph.
3. 2Hi TRAC OFF and VSC OFF​

We could leave the ECU permanently in 4hi, and you get 4wheel traction control, but the modes are not the most useful (traction control ON but VSC OFF is useful)

4. 4Hi TRAC ON and VSC ON.
5. 4Hi TRAC OFF and VSC ON. In this mode TRAC is off from 0-30mph and on over 30mph.
6. 4Hi TRAC OFF and VSC OFF​

You could leave the ECU permanently in 4lo, but i believe that will eventually give you errors.


So this is the issue that resulted in me designing the 2mode spoofer (goes from spoofed 2hi to spoofed 4lo).
That is the schematic on first page.
If you think you want to leave the spoofer in 2hi, 4hi, or 4lo permanently, can simply that schematic...

Does that make sense, I want you to understand the options and drawbacks first.

 

Well that's why I wanted to post because my ADD isn't locked out, I have a wiring harness for a switch in the cab, but option number one would be the best bet of acting in 2hi all time. Just trying to get it back to stock for now with the new case so later I can make those vsc and Trac kill switches. Would the wiring diagram on page 1/post 1 still be what I need?

 

Just to be clear, if you permanently spoof into 2hi, that means you wont have any front axle traction control when you manually activate the transfer case and front ADD. (as best we can tell)

I will need to double check the schematic when not tired, but the short answer is that you will use the schematic from the first post, however you can omit the relay and instead just permanently ground pin 8 and 11 on connector F13 (the second connector interconnect shown)

I will try to simplify it tomorrow (Sunday later today actually), if you think you just want permanently 2wd on the ecu.

 

I double checked and yes I'm fine with losing (as far as you know) traction control on the front in 4hi. Were you able to simplify the schematic at all? I'll probably toy around with that this next week. How many people have you talked to that have a swapped 3rd gen?

 

The only person I am aware of that I eventually assisted in the FJ swap electronics is @Bajataco358. (I am not aware of anybody else I gave guidance or suggestions to utilizing them, although they may have... per my memory). I have helped alot more people work on anytime locker for pro/OR, so its possible I am forgetting somebody for FJ case assistance.

I have revised the schematic with the following assumptions
Truck ECUs will ALWAYS think they are in 2hi
Truck dash dial MUST ALWAYS be left in 2hi
The transfer case actuator and ADD actuator connectors must be completely disconnected and insulated (not shorted out to anything, bagged and stowed).
(Let me know if these assumptions dont match your reality, such as any special ADD harness, etc.)

Note,
The wiring connections shown can be made at the ECU, or at the actuators, or literally anywhere electrically connected, but DO NOT allow grounding of any wire not explicitly annotated as grounded.... The ECU checks for current leakage to ground on the actuator circuits.
This schematic shows the connections (pin numbers and colors) at the ECU, let me know if you want to connect at the ADD or transfer actuator.
The resistors shown need to be power resistors, IF there is any risk of ever turning the truck dash dial. These resistors will see 12V if anybody ever turns that dash dial. The ECU will fault after a few seconds, but it will have quite a wattage into the resistor until then.

THIS SCHEMATIC NOT PEER-REVIEWED YET. USE WITH CAUTION. I AM NOT LIABLE IF THIS TORCHES YOUR TRUCK. I recommend double checking this data against the data in this thread before use (https://www.tacomaworld.com/threads/4wd-actuator-troubleshooting-transfer-case-and-add.578262/)

If any of this doesnt make sense, or these assumptions dont match your reality, please ask before chopping wires.

 

Yes both actuators are disconnected so the actuator wiring harnesses coming out of the ECU does not connect to anything on that end- they're just hanging now. I need some ideas on how to bag them though because I don't deal on much electronics.
As for the schematic, awesome. I'll open up to the ECU and see if I can at least point out wires I'll need to change and send pictures before I touch anything. Do you know the resistors you recommend? I'm actually a mechanical engineer so I've only ever dealt with this stuff on paper and not sure what the industry standard is or if the resistors I've dealt with were just a university thing

 

I would fill the connectors with dielectric grease (like bathed in it), which is available at auto parts store or in electrical section of home improvement store. Get a heavy duty polyethylene bag (like a vacuum sealing bag or double up ziplocks) and just secure it with a tie wraps over the connector. That should be ample for this usage in my opinion.

For resistors, I would just search Amazon for ~1.5 ohm 100w wire wound resistor, should get (2) for ~$6-8. (On phone now so pain to get a link). Those will need to be soldered and heat shrinked to some wire (do that outside the truck.)

(Structures Stress Analyst here)

 

Do you have a schematic for the whole 4WD system? I’m trying to figure out how to maintain the front axle ADD functionality. I know most people just stick it in 4wd or swap in an FJ axle but by keeping the ADD working you can throw in a lunch box locker or weld it up without having the front axle chirping while in 2wd which would be nice

 

This is a big assumption, but if the ADD is setup like the second gen (I don't see why it wouldn't be) then it's been wired up to a standalone switch before, if you dig through here.

https://www.tacomaworld.com/threads/lets-see-your-fj-case-swap.455278/

 

Wiring diagrams for the entire truck are readily available on here somewhere. I don't have a link handy but it should be pretty easy to find them by searching. If I remember correctly there are two limit switches you can monitor to see the state of the actuator. Just two wires to actuate the disconnect.

 

This is the 2016 schematic, assuming I grabbed the right one. (It is assumed the 2016+ is the same... the only thing that has changed that I know of is the Front Diff Temp Sensor has been removed in later years.)

NOTE: If you are trying to use the ECU at all, the 3rd gen ECU includes ALOT of software checks for inconsistent input from the sensors... A single momentary sensor input discrepancy from its expected values can trip it. Sometimes it feels like looking at it cross-eyed will make it Fail-Safe. The one advantage is that it does MOST of its sensor checks on startup and when changing modes (2hi-4hi-4lo-4hi-2hi).

If you are just manually driving the actuator, I am 99% sure the 2nd gen electrical ADD override is similar, but verify pin #s.

Edit, forgot to mention
Details on the position of the limit switches here
4WD Actuator Troubleshooting (Transfer Case and ADD) | Tacoma World

 

Check out my Instagram, Tonya_Tacoma, I do a full write up of the materials I used for my swap.
Not sure if it's what you want but I purchased a wiring harness that links to the ADD and back to the cab as a switch. It throws codes but I have complete control over the ADD and when to actually be in 4wd, no computer involved

 

Random data point I thought I would add. On the second gens doing an fj swap, you can unplug the 4wd ecu and it doesn’t throw any errors or lights. This made the swap pretty easy.

I was curious if that would be the case on third gens because I’m looking into helping my friend with a 2018 trd OR. We unplugged the 4wd ecu to see what would happen and it disabled the abs/vsc/pre collision warning. I assume it has to do with the status signal it sends the skid ecu.

Just thought I would share that little tidbit of info. My first plan was to unplug the 4wd ecu to eliminate dash lights and wire in the locker independently, but now moving onto plan B which is follow this thread.

 

Well join the club! Lol I currently drive around with no abs or traction control. It's not bad by any means, just sucks having my dash constantly lit up with error messages covering my digital speed readout and mpg's. Someone smarter than me will hopefully make a dual connector kit to spoof the ecu at the actuator ends
*cough cough* @BigWhiteTRD

 

Oh I’m already part of the FJ club, I love it on my second gen. My buddy with the third gen has gone through like 4 ADD actuators somehow and he’s just sick of it.