@Skniper was having a similar issue with 'parasitic draw'. Here is the thread:
https://forum.ih8mud.com/threads/fj62-battery-draw-diagnosis-normal-or-not.811681/#post-9274503
I'm not sure if he identified the component/factor that was leading to his battery drain when left sitting for a longer period of time.
There are 3 basis tests for testing whether a component is functioning correctly
1) A resistance/continuity measurement (measures resistance in Ohms) - for example a wire between the battery and the next component in line (say, a switch). The wire acts like a resistor. To test if the wire is grounding (making a short by a hole in the insulation so that the metal wire touches ground) you would disconnect the wire from the battery source, connect one lead from the multimeter to the end of the wire that was disconnected from the battery and the other lead to where the wire connects to the switch (or whatever component comes first in line) BEFORE the switch. Measure resistance/continuity. If it reads ~tens of Ohms, wire is not grounding and is working fine. If it reads infinity, wire is grounding and you have a short.
2) A voltage measurement. To test, for example, that the switch is working correctly. Reconnect the wire that powers that switch to the batter. Connect your red (+) lead on the multi-meter on the other side (not battery side) of the switch. Connect the black (-) lead of the multimeter to ground. With the switch off (open), you should see 0V reading. With switch on (closed), you should see 12V+ reading. If there is a voltage with the switch off (open), the switch is leaking.
3) Current measurement - To test the amount of current (Amperes) running through that circuit. Connect your multimeter in line (so disconnect a wire that leads to a component and connect the red (+) lead to the wire and the black (-) lead to the contact on the component from which you just removed the wire and measure Amps).
If it were a single component/system, the test would be straight forward...but since there are many components/systems, you will need a methodical approach to weed out correctly functioning components/systems and identify the trouble makers.
Just do a quick Google search for "finding a short" or "car battery drain" or "parasitic battery drain".
I saw one Wiki that, with the car off, remove the negative lead to your battery.
Engine off.
Install your multimeter in series between the negative battery terminal and the recently removed negative battery cable.
Measure Amps.
If you see a reading of more than 25 milliAmps, then go to the fuse box and remove each fuse, one at a time.
After you remove a fuse, go back and see if the reading on your multimeter goes down to 0 or remains the same.
If it goes to zero, then you have identified the circuit where there is a drain.
If it stays, the same, go back and replace that fuse and move onto the next one.
Go through all fuses until you have identified the fuse(s) that correspond to the system that is causing the drain.
Then you can work through that circuit...
Problem is, if someone has modified the original wiring harness, then when you get down to the circuit level trouble shooting, you're just gonna have to figure it out...it's definitely doable and the OEM wiring diagram will tell you how it is supposed to work...as a reference...