Open hood.
Take key out of ignition.
Close glove box door, trunk lid and both doors.
Take battery ground cable off.
1) Insert meter between battery post and ground cable, set to 10amp scale.
2) Observe current reading (it will be .1 to .3 amps, if it is zero, you don't have the meter connected or configured properly).
3) WAIT THREE MINUTES - the current reading will go down, as modules hibernate.
4) AFTER THREE MINUTES - any current reading over 55mA (.055 amp) is a problem.

If you have too much current, start pulling fuses until the current drops below .055 amp - Pulling some fuses will cause the current to go UP, this is due to 'waking' a module somewhere, wait three minutes and it should go back down.

If NO fuse causes the current to go down enough, in the little black box next to battery (size of a pack of cigarettes):
--- Remove one 50 amp fuse that goes to engine fan - it is labeled.
If that does not do it:
--- Remove other 50 amp fuse, that goes to brake controller - it is labeled.
If that does not do it:
--- Remove 200 amp fuse that feeds entire car - if that does it, you need real help. My rate is $100 per hour plus $1600 travel expenses.
If that does not do it:
--- Remove BIG red cable from back of battery - if that does it, you need a new alternator (or get the one you have rebuilt, but make sure the guy knows it has a bad diode(s) ).
If that does not do it:
You, again, need real help. My rate is $100 per hour plus $1600 travel expenses. (You should report the car stolen at this point.)