Here I show a couple of better methods to help identify the circuit responsible for draining a car battery over the usual "ammeter in series" technique- but while still using a basic DVOM.
Schrodinger's Box Quantum Mekanix site is here:
My original video on parasitic amp draw is here (not in high def lol) :
Understanding Voltage Drop video is here:
Improved Methods To Find Parasitic Draw (Battery Drains Overnight)