You are correct however, your vehicle does not have a GEM. You have a central junction box that is on the right side kick panel and if your drain is clogged and water is running down the inside paneling it could be into the CJB. If it does you should find water and corrosion inside the connectors or on the relays/fuses.
Take a look at the material below and that will help locate this and identify where these components are. Each of the items you listed runs through this so it is the correct place to start.
Let me know what questions you have. Thanks
Images (Click to enlarge)
Sunday, February 21st, 2021 AT 2:21 PM