2005 Yukon XL Denali RR window issue

[SteveKarns]

I've got a 2005 Yukon XL Denali, that all of the sudden one evening, I couldn't roll the right rear window up, it was only open about an inch so we dealt with it until we got home. I had to search but eventually found that it was powered through the 50A MBEC fuse in the engine compartment. I pulled the fuse and tested it for continuity, It tested good, so I replaced it and then the window went down, no input from anyone. I pulled the fuse again quickly as I was still standing at the fuse panel, went to the right rear door and flipped the switch up and down a few times, thinking maybe it was stuck. Then back to fuse panel and replaced the fuse, this time the window when down all the way and went back up to the top, i went again to the RR door and flipped the switch a couple times to see what was going on, and suddenly it smoked, I ran and pulled the fuse. I pulled out the RR window switch and it was toast, black char and all. Removed the switch and ordered a new one. A week later, got the switch installed it and tried to use the switch, nothing happened, no up, no down, went to drivers seat and tried that, nothing again. I thought I had gotten a dead switch, I installed the switch into the left rear seat and it only works from the drivers controls in that location, pretty sure it is the right switch as it has the same trim panel on it as the right side. With the "new" switch plugged into the left rear door, it only works from the drivers controls. I removed the connector at the window lift motor and found when drivers switch up, i got 12 Vdc, so I thought the motor was bad, replaced it, nothing changed. I did some online searching and found information pointing towards the 25A circuit breaker located in the MBEC. I located it and when I pulled the 25A CB, there is evidence that I've got an issue, brown char/overheating marks. My understanding is that the 25A CB, controls both the front right and rear right doors. I check for shorts to ground on both sides of the 25A CB and on the lower post, i would get about 250 Kohms until i used the drivers door switch to try and lower the RR window, then the resistance would drop to about 50 ohms and stay there, until I removed my meter from the circuit and then when placed back in it would read about 250K ohms. I tried this same thing with the front passenger window and did not see the drop in resistance. I put my meter on Ampmeter and one lead in each hole of the 25A CB, I motored the passenger window up and down and read about 8-9 amps in each direction, slightly higher going up than down.

Looooong story, but I think that is all the details about the window issue. I'm asking for suggestions on what might be wrong, I'm kinda thinking it is the switch in the drivers door, but at this point have thrown enough parts at it that I don't wanna guess anymore, I've gotta get two new rear door window switches, for sure.