I borrowed a meter from a friend and he told me over the phone how to check the fuses by checking meter as each fuse from the fuse box on end of driver's side dash panel. There was significant drop of voltage from pulling #4 fuse (radio) and #19 fuse (Overhead Console, Garage Door Opener, Trunk, Overhead, Rear Reading, and Visor Vanity Lights, Trunk Release Solenoid, Power Mirrors, Power Door Locks, Body Control Module, Aspirator Motor).
Possible suspects:
1) Radio: Ronbo mentioned checking PIN connectors on radio in another thread. "There are 2 connectors on the back of 2002-2004 radios(RB1 included)" However, my car is a 2001 ES...what to check on radio for 2001 (ES model, no CD changer)...Ronbo?
2) Key Switch/Actuator: There was also a change in voltage when jiggling the key in the switch. A few weeks ago, the battery didn't drain after not being started for 8 days, and after I drove it the next day, battery drained completely the next day. From talking with cruzcar and another friend, that is usually a symptom of a faulty switch/actuator. Also, i misplaced the ignition key for the car (chipped), but I have a pass key for the doors (non-chip), which will turn ignition switch but not start the car....so I assume if turns out from responses to this post that the switch/actuator should be replaced, will the pass key work to remove the cylinder? And if both replaced, any issues using a new key (maybe computer not recognizing it)?
3) BCM: I wrote earlier in this thread that the BCM was replaced and I thought problem with display on led gauge of climate control panel working, but now temp reading on climate control is intermittent. There were no led lights from climate control or radio with old BCM, but I may either get it reprogrammed or reinstall as is because after I installed the one from the salvage yard, the odometer reading was 50K higher, which I noticed after car was inspected...if I do that, just hope no issues when inspected again next year because odometer reading will be lower. Since fuse 19 also controls the BCM, maybe the BCM replaced is source of the drain.
4) Glove box light: I replaced the lid to the glove box a few years ago. After replacing it, the light on the glove box was working, but I didn't check to verify if the lid was turning off the light when closed (read in another thread recently the way to check is to remove the panel on end of passenger side dashboard). When I was looking at lights in and around the car about about a week ago that could be causing the drain, I opened the glove box and noticed no light came on, so I assumed there was no bulb in the glove box (I had forgot that there was a working bulb in it 2 years ago). When I open the lid now, the bulb does not turn on...could that be a source of the drain?
5) Door/headlight switch: Interior light was on one morning but thought switch was off night before. Daytrepper posted in this thread "So the headlight switches have been known to go bad and cause the interior lights to come on randomly. That's the most common possibility, other than that it could be a door switch."
Suggestions appreciated where best to start to isolate this problem. If key not found, then I'll need to replace ignition switch/actuator anyway if no issues doing that from answers to my questions in #2...less expensive than having paying dealer to cut new chip key and program it..