Parasitic ELectr. Load - 06 E350 ?

[l_turn9]

Hi Gang, I noticed my battery seemed to discharge pretty quickly over 2-4 days or so. So I thought I'd try a method for finding shorts I had been told was simple and reliable. It seems logical at least.
I disconnected my Neg. Cable and out a Test Light between the cable clamp and the neg. post. The light completed the circuit and the light lit. I hoped I could pull fuses one after another thinking the Test Light would go out when I got to the right one/circuit.
I checked each fuse next to the steering wheel, then then did the same for the fuses in the engine compartment. Unfortunately, the light bulb never wend out!
Now I'm wondering if there is a constant Parasitic Load on the battery? I know there are a number of computers but I thought if the car was turned off, the parasitic lost would be nil. This doesn't seem accurate though -
Is there a better way to test for a short? Please be specific, electrical stuff is not my strong suite. ;-)
Thanks ya'll --