Let's see your FJ case swap

Im sure if you called or e-mailed RST they would supply you with the wiring diagram. Can't hurt to ask. I think the harness is a little over 100 dollars. I honestly can't remember exactly.

 

The harness diagram was a napkin drawing, but worth asking

 

Hey guys, I just purchased my fj transfercase the other day and planning on doing this sometime this week. Anybody have any advice? I have an automatic 06 access cab trd offroad

 

Take the cases apart carefully, or you will learn a lot more about the internals than you care too.

 

Why do need to take the fj tcase apart?

 

Guess you don't because you are automatic

 

Yeah I was under the impression it was a bolt on fix. And how do you do the ADD delete? Would I still need to mess with any electronics besides the lights?

 

Without the electronic actuator in the stock case the FJ case will require wiring for the dash lights to operate properly. When you eliminate the dash 4wd switch you need to install a new switch to activate the front diff for 4wd as the stock switch removal will disable that function. You'll need to manually activate with the case swap.

 

You can only do a true ADD delete by swappin diff tubes or SAS.

 

You're eliminating the 4wd switch because you need the switch sensor wires for the dash lights?

 

No, you are eliminating the 4wd switch because you no longer have an electric actuator on the transfer case. You need a switch to activate the front diff ADD after the install

 

When you turn the dash switch it does two things, engages the front ADD and shifts the acuator on the T-case to 4wd. When you take the electronic case out you will be unplugging the t-case acuation part of this loop making that switch useless. All the wires to make the dash lights work are located at the 4wd ecu behind the glove box. You have to cut and splice 4 wires making that loop further useless.

 

What did you guys end up doing with the empty switch slot? That info is down the important-things-to-figure-out list a ways, but curious about it anyway.

 

Bought a pre-runner blank dash piece and put the new ADD switch in place of the 4wd dial.

 

Didn't even think of that. Nice work!

 

Certainly

RST does indeed sell a wiring harness "plug and play", I think around the tune of $100-150. You can make your own for the tune of around $30 and maybe 2 hours of your time, and also customize it to your liking. The ADD circuit is no different than any of the TRD differential lock circuits, so you can replace the ECU function with a DPDT switch.

Front ADD circuit, you are dealing with the circuit in the top right of this diagram. There are a total of 6 wires that control the ADD, two for the motor, two for the limit switches which control when the motor stops in either direction (locked or unlocked) and one for a limit switch which is used to control your 4wd light on the dash. When you do the FJ swap you will now want the 4x4 dash light driven directly by the transfer case, so when you swap the FJ case in you cut and cap the wire going to the ECU from the 4x4 transfer case switch and tie it directly into the dash light circuit, this goes the same for the 4lo dash light. The limit switch on the ADD is now used as an indicator light on your new switch to tell you when the front ADD is engaged or disengaged.


You take that circuit and deconstruct it and rewire it to a DPDT switch, the carling part number is at the top of this schematic I made showing how you will rewire the circuit. It is optional to add illumination to the switch, but certainly a nice feature. To do that, simply tie into the stock illumination circuit 12V and variable ground. You can use a momentary or maintained DPDT switch, whichever your preference.


Here you can see the switch pre-fabricated getting ready to wire it into my truck.


Another switch I've made up for @HomerTaco


Here is wiring into @HomerTaco's truck


Here's a test of the switch


Another option instead of controlling it electronically is to leave it permanently engaged in the engaged position, or delete the ADD entirely. More details on that in this thread

https://www.tacomaworld.com/threads/how-to-deleting-add-system.427258/

You can put the ADD switch anywhere, but what most people have done is get rid of the 4wd stock switch and then buy the toyota pre-runner switch blank that goes there, and then put the new ADD switch in that switch blank.

On a side note, I have an ADD switch and wiring setup I'm currently not using that I'd be willing to sell if someone does not feel comfortable making their own.

 

Perfect.

 

Thanks for posting 6 Gear T. I saved your diagrams for the future.

I wouldn't call myself electrically challenged, at least compared to most, but it might take me a minute or two to wrap my brain around this DPDT thing. Perfect reading for a rainy afternoon holiday. Cheers!

 

ADDs are overrated

 

Finally started my FJ swap!