Received the wiring diagrams (thanks Charlie) and most of the diagrams between the 4wd switch and "ADD" system are nearly identical. The junctions, ecu pins, wire colors are almost all the same.

The 4wd select switch actually ties to the same connections the transfercase detection switches connect to.

So... a switch can do 1 of 2 things and have 1 of 2 different results. A simple switch can:
Open current or close current

The results could be the signal received is ground (whether self grounded or through a system) or the signal received is voltage.

In this case it doesn't matter.

In both diagrams the constant is the W-B wire to the 3 transfercase detection switches... the only variation being the outputs on ADD run through the ADD relay to the VSVs and the 4WD ECU controls the transfercase and then outputs to the VSVs. The W-B is ground as notated on pin 8 of the 4wd ecu (and they all connect).

So, in short, the 4wd switch simply sends a ground to the 4wd computer on pin 5.

It also receives a ground signal on pin 6 from the transfercase 4wd detection switch.

So... if I plug in the manual sr5 harness and it seems that the 4wd detection works, then I simply would need to jumper pin 5 and pin 6. This would effectively tell the limited 4wd computer that the "4wd switch" is clicked when the J shift transfercase "detection" switch grounds out. It seems the junction location and wiring is almost all the same... almost.


Now I could be wrong, but I doubt the 4wd ecu will actually care if the transfercase motor exists or not. The ecu simply outputs a signal to the motor (probably in actuality 2, one for in and one for out) and stops trying when it gets ground from the 4wd detection switch.

We will see....