At the risk of being told I don't know what I'm talking about (50 years as an electronics technician and mixed in with that professional auto electric), I have a couple of neat tools for finding shorts.
Part one is a circuit breaker in a plastic tube with rubber caps, wires coming out with alligator clips on each end.
Remove the fuse, clip across the tabs, then using part two, which is a low read ammeter with a clip on the back, turn the power on.
The circuit breaker will click, click, click as you move the ammeter along the wiring. You will soon find which wire is causing the draw.
GENERALLY there is a wiring connector or LUCAR in-line to unplug and isolate that circuit.
If the wiring is somewhat stock, find the colour in your diagram and you'll know what to open up.
If you think it's the panel dimmer, unplug it. Eliminates dimmer and dash lamps.
Why that would be an issue if the lights are not on, well, you'll be able to tell as you dive in.
Do this fast, as in all hooked up, quick test to isolate, and turn the ignition OFF.
My unit is a 35A, I think, but you can use as low as 10 or 15A circuit breakers.
I bought mine either off a tool truck or off a NAPA rack decades ago.
Me?
I'd use the breaker, unplug everything on that circuit, and start plugging in with key on until you hear the breaker go, that's the circuit.
Dave