Water Leak :(

[Mad Max]

It was raining like mad today and the horn in my truck went off all by itself. I pulled the fuse panel and found water leaking down from under the dash.

I know I read about this problem a long time ago but can't find it. I think it is the windshield seal but I want to make sure before I have the windshield replace.

Please let me know if anyone has experience with this problem and how to fix it.

Thanks....