Today was finally junkyard day, and it taught me a few things about how these switches are assembled. Apologies in advance for the images; my phone was being exceptionally potato-y about that today.
Firstly, there are a couple of different revisions of the switch. I pulled one from a 2002, and it had a backing plate on it:
But the one I pulled from both a 2005 and 2007 did not (this is from the 2007):
I'm actually cheating a little here - the photo of the switch with the backing plate on it is really the 2007 switch with the 2002 backing plate snapped on. In the process of eyeballing them, the PCBs were marked with different revision numbers, but a quick look didn't turn up any major differences between the two, including values marked on individual components as well as the layout and location of the pins that connect back to the wiring harness. I haven't run this switch assembly in our '05 yet, but I suspect that 2002-2007 will interchange just fine.
Anyway, here's where it starts to get interesting:
That's a closeup of the switches for the front windows. Note the arrows pointing to the microswitches embedded in the switch mechanism itself - those are responsible for giving the second click you can feel when pushing the window switch fully down to activate the auto-down feature. With that in mind:
In the foreground are the switches for the rear windows. Note that there are no microswitches in the mounting holes.
In the background are the switches for the front windows. Note that there is a relay mounted to the PCB beside each switch. From doing a quick (but by no means extensive) chasedown of the circuit on the PCB, these relays control the auto-down behaviour.
Because there is no provision on the PCB to add these relays and the associated microswitch for the rear windows, there is no good way to add auto-down for the rear windows. Could it be done? Probably, but you'd end up with a hacked-up mess that would be a real pain to package back into the centre console. Long-term reliability of the modification would also likely be very questionable.
Auto-up (even for just the front windows) looks to fall into the same category, but with an additional caveat: the switch bodies only have mounting holes for the microswitch on the 'down' side of their operation, not on the 'up' side. It would take some very careful work with <insert rotary tool here> to add the appropriate hole to the other side of the switch body - at which point you're back to the relay issue, since you'd need to do some jumpering to the relay to make it work in reverse of how it's normally intended to.
Anyway, I'm calling this idea dead - it's just not worth the effort involved for what you'd get out of it. Thanks to
this thread on jeepforum for pointing me in the right direction re: removing the window switch caps, which was necessary in order to separate the PCB from the casing.
For reference, here are some other photos that I took of the PCB. Not embedding them since they're no longer terribly relevant given that I'm not going to pursue this any further, but someone else might find them handy if they feel like putting the time and energy into this that I'm not:
https://i.imgur.com/pyY7X3Q.jpghttps://i.imgur.com/NRpyQkG.jpghttps://i.imgur.com/Qkp5UsE.jpghttps://i.imgur.com/AsyOAMd.jpghttps://i.imgur.com/92NJ8oY.jpgOh, and a footnote: there's another unrelated project I have in mind. This one, I think, has a better chance of success. Here's a hint: