airbag fuse blown

[MrIgor]

I bought the truck and the airbag fuse was blown. I replaced it everything was working fine until a passenger gets into the seat AIRBAG ON shows. When passenger gets off the seat fuse blows. Sometimes it will shows AIRBAG OFF before it blows it, sometimes no. The seat had a large water spot on it.
My question is this: is seat sensor is bad, why is working with new fuse and not just turning on airbag light with error REPLACE SEAT SENSOR? OR is it bad wire somewhere, please fill me in.

2006 Hummer H3