I have excessive condensation in the trunk of my 1999 Seville SLS. I had the same problem with a 1988 Seville too.
Anyone else ever have this situation before ? The spare tire is wet all the time & trunk carpet gets wet at times. Any ideas
or help out there ? Thanks all. Jim

 

I have the same problem with my 99 SLS but I think that it is leaking because after a hard rain around these parts the spare tire hole becomes a reservoir for water.

 

I had the same issue with my 1995 Seville SLS. Finally resolved it after we heard water sloshing under the back seat. WaterLeak Techniques in Edmonds, WA resealed the back window and the trunk has been dry since. The car is 100% parked outside in the sometimes rainy Seattle suburbs. Dick in Lynnwood, WA

 

Hi, I was wondering if you live in a state that gets snow?? I have a 99 STS and have "water" in the trunk. I think I know why. I think Ice got under the edge of my deck lid and created upward pressure, creating a barley noticeable gap in the middle of my trunk seal, I haven't got my new seal on yet to test my theory, but I will post as soon as I do to share my results.