You could pull the battery and take it to be tested at a local auto parts store.
Here's a link to an overview of how to test for a drain.
https://www.batterystuff.com/kb/articles/charging-articles/testing-your-battery-for-parasitic-load.html
I had one that turned out to be on the front defroster circuit in my SC. My car did not have a front defroster but apparently the factory installed the same wiring harness regardless.
After I disconnected that wire from the fuse panel it was fine. After disconnecting it I had less than 10 mA regular draw.