mbfireboat

I had the same in my Yukon Denali. I could hear water sloshing around behind the dash when I turned and the passenger side floor was wet. I got a can of aerosol AC/evaporator cleaner that comes with a flexible hose and nozzle. Most auto parts stores have it for around $15-20. I removed the front wheel liner and and squirted the contents into the drain line. It not only clears the drain line but also cleans the evaporator. Worked very well and not that hard to do.

I had this consistently for maybe two days around a year ago on my 2019 5.3, then it stopped. It only has happened once or twice since then. It was a very hard downshift at around 5mph when stopping. I think I had 1400 miles on it at the time. Before I picked up my truck new from the dealer, they had performed a transmission flush per a TSB to a newer spec fluid. I don't know, maybe I had some moisture in the tranny.

I have had my 2019 LT Crew (Ft Wayne build date August 2018) for over a year and now have noticed it does have dried water trails on both sides of the rear window. They were not always there. I doused it with a hose from all angles and I could only get a couple of drops coming down the window. The headliner is fine. I'll wait till I need to bring the truck in for service but I dread the possibility of them screwing it up.

Wonder why GM dropped the SD card upgrade? I did it three months ago and it works very well.

All I can say, not everyone is having this issue, but the transmission is probably sensitive any slight defect. My 2019 5.3 8-spd did the very hard downshift just before stopping right at the 4000 mile mark, but only for two days. It then resolved itself before I could take it back to the dealer and has not done it since. It upshifts and downshifts smoothly and actually seems like a pretty good transmission. I have 8000 miles on it now. The dealer did a tranny flush before I bought it. I would be upset also if the problem kept up. It would be hard to live with. But the 8-speed transmission does work well as designed. Hope you get it straightened out.

For those of you that did this, what did you do with the B3 wire that was in the UEC already? The instructions seem to say to just take it out and tape the end with electrical tape? It seems like this wire should be doing something? I also had the brown/white wire at the BCM already so I did not do the jumper wire through the firewall. Thanks

Interesting, I guess it is possible to add rain sensing wipers?