Tacoma ADD Delete Wiring Figured Out

Havent found much/any help on this topic so i spent the time to figure it out. Did the FJ AWD front diff tube setup and tackled the wiring. Here is the basic breakdown of what needs to be going on. When you try to engage 4x4, the 4x4 ECU is looking for the ADD to activate fully before signal will be sent to the transfer case.

Disregard the circled part on the diagram. Purely for a visual. (white/black is shown outside but its pinned between green/black and pink/blue)


The ADD has 6 wires that control the action as well as engagement/disengagement confirmations. Your wires may differ in color but this is what i had on my 2008. This is how my wires came in the ADD connector.

1 - Red - Power for ADD motor
2 - Black/white stripe - Ground for ADD motor
3 - Green/black stripe - ADD engagement confirmation
4 - White/black stripe - ground for confirmation wires
5 - Pink/blue stripe - (I believe this is power cut for ADD motor)
6 - Green - ADD disengaged confirmation

In 2wd, 4 connecting to 6.
In 4wd/4LOW (after the ADD engages), 4 disconnects from 6, then 4 connects to 3 AND 5.
You can disregard the ADD power/ground since you wont have the ADD anymore.

Its as simple as that. Everything is run off ground (with exception of the red wire). The problem with the schematic, is that it doesnt properly(clearly) show 6(green) being disconnect. It took me, continuity testing every little bit on the ADD actuator motor cover, to figure this out. The sweep pattern at both limits has one contact breaking connection.

This whole connect/disconnect/connect can be accomplished by a single 5 pin relay.
87a for 6(Green)
87 for 3(green/black) and 5(pink/blue)
30 for ground source (4-white/black)
85 for ground
86 for positive (switched to 4wd source)

Next, i'll figure out which wires to tap into at the ECU.

 

Subbed for any future info / development.

I am going to try to make a cable actuated ADD but barring that I'll go the FJ route. Either way I'll be needing to know what signals the ECU wants to see

 

I didnt figure out the automated ecu signal flow. I'll have to dig up the pinout for corresponding wires at the ECU. I ended up using the 5pin relay with a switch like our fog light button.

 

Why don't you just yank the 4wd ecu if you don't have the add? Are you still running the stock transfer case?

 

Mine is stock for now but I have an FJ case coming soon; right now I'm just trying to get all of my ducks in a line.

What side effects would yanking the 4x4 ECU have? Surely it would affect the Atrac or the rear locker?

 

Personally, if i were in your position, I would hard wire the A-trac with a relay using the existing switch. Also once that FJ case goes in, yank the 4x4 ECU. You will only have to connect the transfer case position sensor wires to the dash lights.

After that, pull the ADD cable, throw the lever on the FJ case and when it engages 4hi, the 4x4 light comes on. 4Lo, Lo light comes on. There is a decent thread on that FJ case dash light wiring.

 

Yeah when I do my swap this is what I am doing

 

Any chance you have a link to this thread?

 

I just ordered a latching relay and am going to try and solder it into the old ADD actuator housing/connector. I've never done anything with relays like this before, but from reading about them it sounds like the latching relay should be able to simulate the ADD using the reversing polarity from DM1/DM2 (ADD motor power) to set/reset the relay between the ADD engaged (4 connected to 3 & 5) and ADD disengaged (4 connected to 6) circuits. Will report back once I've assembled and tested.

 

But you are using an electronic AWD tcase from a 4Runner or Lexus, right?

So why not make it real clean and get the awd computer from eBay and run a non ADD axle tube?

 

I have one. Let me go try it. When I plugged it in before it just made the 4LO light flash repeatedly. From looking at the wiring diagrams it seems like it might be harder to use the AWD computer than to trick the existing computer into compliance.

 

So it does plug in?

FYI I've seen it many times on toyotas that connectors plug together but pins may have to be swapped.

Good luck. Seems like you are close to a AWD LSD traction monster!

 

Yes, the pins are in different places according to the wiring diagrams, but the connectors plug in.

 

Sub'd

 

Sub'd also, I like a good tech thread!

 

You are correct. The latching relay should work. I ordered one a long time ago to try this, but my setup works just fine with the switch so I never really bothered. Might have to dig it up and finish this project.

 

So this setup would use a manual FJ t-case, then install the FJ AWD front LSD differential and hubS?

You would run in 2WD, but when you shift the t-case lever into 4WD, it would activate the LSD AWD front differential.

Like on the fly AWD?

Just trying to understand If I'm understanding it right, sounds like a nice setup.

 

There are no LSD front diff carriers available, only lockers(aftermarket) or open(stock). The AWD FJ did not have 2wd. Its default state was AWD then you shifted into 4x4. But you would need the AWD specific transfer case which I believe was for manual trans only. It was AWD with 4x4 on the fly versus 2wd with 4x4 on the fly.

The setup lostsheep was referring to was a basic 4x4 FJ case (shifted via lever) with a custom lever/cable actuated front diff disconnect. He still wants the option to disconnect the front diff, but without the reliance on electronics. And since both mods would do away with the electronics, I was explaining that the 4x4 ECU would not be needed anymore as the dash light indicators can be wired up directly from the t-case position sensors.

Everyone uses the same standard hubs/flanges that dont have the lock/unlock option. There are aftermarket kits that allow you to convert to lockable hubs, but thats a different piece of pie.

 

OP thank you for the explanation. I have a Pre-runner. Eventually, as parts become available I plan on doing 4WD mod. I bought the engine, trans, t-case and front driveshaft out of an FJ. The engine is in. The trans and t-case are in the shop waiting for a new home. I have always been concerned about wiring. I re-read the thread. Since mine is a pre-runner, once the front differential, trans, and manual shift t-case is installed, does this mean that I really do not even have to worry about wiring? Just manually shift into 4WD like an old truck before all the electronics were introduced?

 

I'm not an expert on the wiring here yet, but since you bypass the 4x4 ECU( in your case, you won't even add it), you should be good to go. Toyota tends to wire for every option package from the factory, even if the actual option is not included, but I find it unlikely the Prerunner dash has the 4x4 lights available, so at the very least I would want to wire the sensor on the transfer case to illuminate a 4WD indicator light. A Low-range light probably isn't necessary, but a 4x4 dummy light is always nice for this dummy.