Originally Posted by pavelvoivoda

I think that the OEM back window lock switch (or any one of the simple push button rectangular switches) used on Gen3 4Runners, that do not have power windows, can handle that power... i think! Contacts seem thicker than the 30 amp fuse's burn point in the casing.

I don't think you'd need a relay. I assume if you open/close all windows at once, it should not draw that much current. But if you have a motor or two that fight against old window seals to raise or lower the glass, then yeah you could get higher amperage draw.

Give it a try, I think that since you are always there when you raise or lower the windows, you will see if the switch that bridges the wires, gets too hot... and you could always say short it intentionally, to see if it will handle 30amps thru and burn the fuse, or if it will spark and melt! haha

If you want to put a relay in the door, here is a edited diagram of the same thing with a relay. It is all doable right there at the door controls bezel