2001 Olds Alero Battery Drain Issue

[Xenokira]

Hello, I stumbled upon this forum trying to find some information on a problem (well, one of many problems..) I'm having with my 2001 Alero (Approx. 135,000miles).

This is the original symptom:
When I try to start my car, the entire thing is dead. There's no power to anything. I tried to jump the car, but I couldn't get enough charge on the battery to get the car to start. The battery in the car looked like it may have been the original one, so I didn't think much of it when I went out to buy a new battery. Once I got the new battery, the car started right up. I shut off the car and went inside. A couple hours later, I came out to run an errand and the car was dead again. This time I was able to get it started with a jump.

So, from this I concluded that something was pulling excessive amperage while the car was off. I used an amp-meter to monitor current as I pulled each fuse under the hood and inside next to the driver's door. Before I started, approximately 600mA were being pull off the battery while the car was off. The only fuse that made any significant difference to this number was the L/H BEC BATT2 maxi fuse under the hood; after pulling it, current fell down to approximately 30mA. Without this fuse, I can't really do anything with the car (won't start, lights don't work, radio doesn't work, keyless entry doesn't work, etc.), but pulling it when I shut off the car does prevent the battery from draining.

I've been putting up with this problem for about a month now. I don't have much money or time as I'm trying to finish up college. I also don't know terribly much about cars, but i want to try and minimize costs before taking it in somewhere.

Has anyone seen a problem similar to this or have any recommendations on some simple things I can check? I know 600mA is quite a bit of current to be pulling off the battery when the car is off--but because so many things seem to rely on that L/H BEC BATT2 maxi fuse, I'm at a loss as to where to start.

Any help is much appreciated, thanks!

EDIT:
I forgot to mention that when I need to start the car, I just re-insert that maxi fuse. As long as I start the car right away, it seems to start normally and runs normally. Then, once I need to shut the car off for anymore than a minute or two, I pull the fuse to prevent the battery from draining.

[BNaylor]

Welcome to AF.

I checked the GM factory service manual for you but that specific fuse is hard to find. Try re-inserting the fuse and disconnect the body control module (BCM) located under the passenger side dash and then check the current draw/parasitic drain.

If you get it down to 30mA that should be good. It is based on the reserve capacity of the battery.

[Xenokira]

Thank you for the response to my thread! I pulled the BCM unit (small black box right?) out today and monitored the drain on the battery. After pulling all three connections to the unit, draw on the battery fell to ~520mA, but still considerably higher than it should be. The first two connections I removed from the box didn't make a difference, but the last connection made drain drop by ~80mA. My next question is why would the unit be pulling 80mA? Without the fuse, only 30mA are being drawn. Could I have multiple things causing this issue?

I haven't really been able to find any information about this fuse online either. I wish I could at least find a list of the systems that are powered off that L/H BEC BATT2 fuse so I could pull one component off at a time.

I'm really at a loss as to what would be causing this

[BNaylor]

The BCM could draw that much while active or at least until shut down mode like after retained accessory power (RAP) activates but it sounds like the BCM isn't the cause.

Trying to decipher what L/H means. I think it is related to left headlamp or related circuits? Maybe try the DRL (daytime running lights) circuits next?