The driver's rear window in my '17 SC F-250 started not wanting to roll down reliably. The issue only occurs while attempting to roll it DOWN using the switch from the driver's position, but when this issue is happening, the same window does not want to roll UP when using the backseat switch. Any thoughts based on this behavior? Thanks!

 

Sounds like it could be a bad connection. Seen some guys with F150 having problems with the widows and the wires from door to body were brittle and came loose. The wires were binding in the boot wire cover and came apart. You can slide the boot down to inspect the wires.
Second could be the drivers control panel could have a loose plug in or became defective. I did see someone use a second control panel to test if the original was bad. Not sure where they got it but it worked on all windows and a new control panel was purchased.

 

This has continued over the past year or more, but hasn't been enough of a problem to **** me off, until today, when the rear pass. side started doing it too. Both sides were acting up badly, suddenly. It is more hot and humid today though than it has been, so maybe related.

I went ahead and removed the driver's door control master switch or w/e you want to call it. You pry it up from the rear, near the rear window switches vs. the side mirror adjustment at the front. My trim tools only bent and/or were too thick to be of any use, so I broke out two small flat blade screwdrivers and popped it right up with minimal issue and zero damage to anything. Once removed and unplugged, I brought the switch assembly inside to work it over. There are 3 black T10 screws that hold the switch assy. to the door trim, then once detached, there are 5 small Phillips screws holding the two halves together. Once removed, there are 6 plastic tabs to sneak past the housing. I did 3 on one side which was nearly enough to separate the two halves, and didn't risk bending the contacts at all. The other 3 tabs popped out easily, leaving me with the circuit board, a mess of little switches, and the rubber pad w/ contacts to deal with. Be careful here, as the little switches can easily fall out and get misplaced, installed improperly, etc. Some of them also stick to the rubber pad and have to be removed and reinserted in the right place, so take your time and it's no big deal.

Everything looked new inside, zero grime or wear. I sprayed the whole circuit board down with CRC electrical parts cleaner, then hit each contact with a q-tip and 99% iso. I then did the same to each contact pad on the rubber piece. Everything came out clean as can be. After re-assembly, I shot some dielectric grease on the switch connector connected to the truck, smeared it off / down into the connector holes, reconnected things, and tested the switches, and I couldn't get them to act up at all. SWEET! Something I noticed about these particular contacts, is on the rubber pad with all the usual black rubber contacts, these 4 contacts are actually gold/brass for some reason. I assume this is the likely culprit.

Fingers crossed that this works long-term. Will report back if not.