Since I have 4 vehicles functional at once (very unusual for me) I don't drive the Saturn as much as I used to.
I've noticed that the battery will consistently go dead over a period of about 7 days of sitting.
Nothing plugged into the accessory port.
Anyone else have this experience? Thoughts?
This car did have the crazy locks thing going on several years back and I "fixed" it by pulling one of the fuses.
I'm wondering if it's still trying to do crazy locks and the BCM is using extra power as a result even though the circuit to the locks was disconnected by pulling the fuse.

 

I don't see how the BCM could be pulling power if you removed the fuse for the locks, Jam. How old is the battery and have you load tested it? Sounds more like a dying battery to me than anything else. If not, it's a parasitic drain and you'll just have to start removing one fuse at a time until you find it, I guess. Sorry I can't be of more help, but electrical has never been my thing.

 

I concur with rubes assessment. Especially if you have ever absolutely drained that battery to zero. They are never the same once you run them too low to start too many times.

Easiest way to check for parasitic BCM drain is to pull both BCM fuses. I think there are two.

 

Cool beans, derf. I had no idea the BCM has two fuses. See? I learned something from you today!

 

Slight update:

Battery was indeed going bad. Replaced it with the battery from our wrecked Equinox.
Then after loaning the car to our daughter for a week when she went to start it to bring it back it was dead.
I went over to try to jump it and it just wouldn't do much of anything.
I ended up jerking the positive battery cable around and all of a sudden it would crank just fine.
So apparently I have a failing battery cable and it's probably what killed the other battery.
Of course once I got it cranking I had to fight to get it to start.
I might have a failing CTS again.
I had to floor it and keep cranking even after it started to kind of run since it didn't have enough power to stay running by itself.
That starter surely hates me now but at least it finally did begin to run ok on its own.
Starter still working ok too.
Temporarily parking my new to me Honda for major seal, oil pump and timing belt change.
This Saturn is now my daily driver again and still running on three cylinders.

 

It will continue to run on 3 cylinders as long as you keep the oil up
make sure you disconnect the power to the fuel injector for that cylinder so you are not throwing raw gas into the cat.

All brass ECTS s don't fail all that often.

My SC2 s will do exactly what you described if you have too many cranks and the engine doesn't start. I think it pretty much floods or the equivalent on a fuel injected car. Mashing and holding the gas pedal clears the flood or shall I say turns off the injectors so that you are not throwing even more gas in.
The mix eventually sorts itself out, but it's but it sputters and you have to feather the gas till it gets back to normal.

I wouldn't mess around too much with the failing positive battery cable. You are bound to get yourself stuck somewhere. Replace.