just something I found. might have nothing to do with your problem but you might want to take a look.
Fix the Chevrolet Intermittent Electrical Problem for Good (fixmyoldride.com)
I had already considered the cable end of things. The + terminal cable had a little corrosion so I lopped it off and replaced both cable ends.
Pulled the fuse box this morning and everything looks fine visually. No evidence of corrosion or burning.
Started doing pin out checks on the BCM and found 6 pins over 2 of the 3 connectors that are powered up at all times; and that is with every fuse/relay in both the dash and under hood fuse boxes cleaned out.
I’m baffled as to why one would power up without a fuse; much less 6 of them.
Next step I guess is tracking each of those 6 down to see if there is a common denominator powering them up. Not like I don’t have 18 other things on the fire… 
Makes me appreciate my 1944 Harley even more. A crescent wrench and 2 ended screwdriver clamped to the bike with a pair of Vise Grips gets me through most problems on the road.
Blew a 2" piece of head gasket on the rear jug out once 30 miles west of OK City. Loosen the head bolts, push the gasket back with the screwdriver, retighten head bolts, and use the Vise Grips/screwdriver blade on a cooling fin to keep the gasket in place. Crude but effective and better than walking…
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Been out of town this past week and have had to put the 1998 Irritation on hold for a bit as a couple or five other things have cropped up.
At the point where I stopped I seemed to have found the current draw and offhand it points to the keyless entry module which is tied into the same lead as the BCM. Have not dug far enough into it yet to say yea or nay on it but having a hard time seeing a 2+ amp draw in that module.
When, and if, it gets sorted I will post results…although taping the keys, title, a 100 dollar bill, and a note saying “Take it” to the windshield has crossed my mind.
Any of us who do our own repair work have similar stories of mysterious electrical gremlins that make you want to consider insurance fraud. They mostly get fixed because I haven’t seen any stories that ended up in criminal court, but they do bring you down. When the solution shows up, it’s usually accompanied by a self administered dope slap.
Can you disconnect the keyless entry module completely?
The deal was $500 for anything that can roll into the dealer. Very attractive and legal. I really liked that car.
The oddity continues. Sat. evening the 2+ amp current draw was still there and would run the battery down pretty quickly. If the schematic is to be believed (and I’m dubious) the BCM and keyless module are tied together.
With both module and BCM unplugged the draw was still there.
Sunday evening I go out for a look and the draw is gone. Vanished into thin air with not a trace.
The current draw now is 71 Milliamperes. No idea what spec is on this truck but that sounds reasonable based on other vehicles I own. I wiggled the crap out of all of the wire harnesses to see if it would reappear but nothing.
Battery is still fully charged after sitting all night and cranks over fine. Won’t start but that’s another issue that hopefully a key relearn will fix.
Maybe the flux capacitors are interacting with the phase recharge interceptors that always ionize as the solstice approaches. Burning sage in the left rear wheelhouse can sometimes change the aura.
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Tried that on a Pinto. It didn’t work.
Try that on a pinto, you might get a hoof in your face.
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You are way ahead of me but I have had two phantom draws on two different cars. I only found out why by accident. The first the battery would run down in the parking lot. One night went into the garage and the interior lights were on. Traced it to rust on the door handle inside the door turning the lights on that were supposed to go on when you pushed the button on the handle.
The other one the car was dead sitting in the parking lot. Pulled fuses, couldn’t figure it out until the test light all of a sudden went bright and went off when I disconnected the electronic level control. No problem after that.
There comes a point where cars with intermittent electrical issues should be shot and crushed.
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Best idea I have heard in a good while. 
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I had a real testy draw once. I don’t remember the vehicle but I think it was a Ford. Drawdown test showed normal but still had battery drain over night. Turned out to be the rear wiper motor would actuate intermittently. Found out it was a known problem from the web. Replaced motor, problem solved. But if I recall your drain is with fuses removed, so not much help. Other than maybe suggesting a long term draw test with multimeter set to min\max mode.
The two circuits that don’t sport removable fuses appear to be the starter motor, and the alternator. Try disconnecting them one at a time when you’re getting the unexplained draw, might provide a clue.
I’ve already weeded out the starter and alt. circuits. The only other non-fused circuits are the fuse box lead and the main power lead to the ignition switch and those go through a fusible link.
And it continues. Sunday evening the draw was gone. Battery still up this morning so I installed the BCM and went through the key relearn. It took that with no problem and the truck started right up. Started it half a dozen times over the next few hours with zero problems.
So at sundown I go out and ta da…battery dead again. It’s on the charger tonight and will check the current draw again tomorrow. Only thing I can figure is that is came back from wherever it ran off to.
I wrestled a weird fuel injection problem on a Fiat once for 2 weeks (not constantly) but this one is starting to top that.
I know you are very knowledgeable, is the theft light still on? As my initial post thinking ignition switch, plan b some live wire shorting out to ground possibly door lock wire. Thanks in advance for being kind.
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Clearly, it will be the last circuit you test. 
. Good luck.
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Always is. 
Time to apply the laws of physics. Whenever there’s a current flow, there’s a magnetic field. There are probes available that detect a magnetic field. A person could make one themselves using an old crank position sensor, anything that uses a hall-effect device. Even easier, use a small direction-finding compass. Like from your boy scout days. Then you should be able to to narrow down which wire has the 2 amp flow.
Don’t give up btw. This has become a fun thread to read 
At this point I’m guessing there’s something problematic in the security electronics.
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I don’t think it’s fun for ok4450. he is probably ready to pull his hair out.
Some problems I’ve had like that turned out to have a pretty entertaining path to the solution. As long as there’s no time schedule to worry about, keep trying something different, eventually OK will crack it, and have a good story to tell.