How to test for parasitic draw when the draw kills the battery in 10 minutes?

Thanks for the advice! I messed around with it for a while with just the positive battery terminal connected, then I disconnected a ton of different circuits one at a time while tested the battery to ground with a test light. I finally found it! The starter solenoid has several other circuits connected to the same post, I tested for a short to ground for each of the wires and one of them has a short... I'm not sure exactly what this circuit powers, but it follows a bus to where all the interior controls are (steering, ignition, lights, ect.) I already pulled all the fuses and that didn't change anything so the short must be before the fuse right? My next step is just braking upon the bus and looking for the short. Once again, thanks so much for the input!