the way i tested my truck to locate a drain was to get a old light tester, not an led one but one with a old flashlight type of bulb, dissconnect one battery completely and then on the other just disconnect the positive only,take the tester and put one end on the terminal on the battery,(i taped the pointy end to the terminal) then clip the other end to the lug or clip that comes off the battery,the light should be on now, as you start pulling fuses the light will get dimmer as you find something that is making a draw,it takes some time but its a way to pinpoint what fuse is making the draw and then see whats on it,mine actually turned out someone put the wrong relay in so my heat and ac would still run after the truck was shut off
Boy, I'm not sure it's going to be that simple.......
First, the truck ALWAYS has some draw (it's supposed to) and the amount of draw diminishes over a half hour
Your procedure is
correct, you should disconnect one battery and test with the other. But, if you use a multi-meter, in the "AMP" mode with current flowing thru
the meter, you can see the current getting lower & lower as the minutes pass (mine would peg until the dome light went off
IIRC after 30mins or so mine was under 150mA when everything is OK. BUT you have to leave it Alone! Close the doors and just walk away and come back
Then, if you Do have a high draw somewhere, you can start to remove some fuses but, remember, there is
stuff (pcm / gem at least) that will show a drop in draw when their fuse is pulled, but that could be Only showing you that they were using what they're supposed to....