Please consider whitelisting my site in your ad blocker. If you must keep it running here, please support this endeavor and select a support plan - which starts at only $0.16 cents per day. I'm not asking for much. I just need a little help. Thank you. Click here to select a support plan.
My advice for a free, quick test: Find ANYONE with the same or similar model car with the same driver door SWITCH module, and ask to temporarily swap it out (easy to do, but practice on your own car first!). My mom's 2003 (or so) LeSabre switch matched mine, a 2000 LeSabre. The quick swap fixed the problem. Both Amazon and e-bay have replacements. I got mine for $35 (guaranteed). Or the junkyard -- make sure you test it in your car while you're there, & return/exchange if necessary. If that doesn't fix the problem, THEN proceed to the more difficult diagnoses (inside door module, wiring diagrams, etc.).
We have a bad power window master control switch on a 2001 Regal, which is a common failure.
Driver can not lower the rear passenger window but the window switch on that door works fine. So all windows do work.
We went to a junkyard for a replacement switch. That fixed the rear passenger window (but the driver's side window stopped working lol).
The junkyard switch unit had a bit of water damage. I spent an hour trying to open the junkyard switch with brute force for repair; it was very greasy and didn't open. Junkyard module was newer than 2001. GM did use a lot of different modules over the years so I see some on the internet can be disassembled.
I have seen new switches sell for about $15-$100. Given high failure rate of these switches and low replacement cost, I might avoid junkyard.
Below is an example but you need to make sure layout of buttons and connectors are the same as those on your car. Not lowest priced supplier and I have no experience with them. . .
Some time after fixing mine with the replacement driver door switch module, it started working intermittently. Pulling on the wire bundles would fix it sometimes. After removing the door panel, and lots of tugging on lots of wire bundles, I finally disconnected the large blue & black multi-terminal connector, I tugged & pushed all the wire inserts, I reconnected, and that fixed it. So it could be poor connections on any multi-pin connector.