1999 Pontiac Grand Am

How long did it take for it to go down? The battery was installed at 730. When was it dead? Either way, it sounds like there's a bad draw on the battery. This can be a tricky problem to diagnose, sometimes. Let's try being more specific on how long it takes to drain the battery and so on. We can do this. Come back with a little more info and I'll help you figure it out. If it's draining like in half a days time, that's a bad draw. If it's taking it a week, then it's not so bad. We need to find out that kind of info.

Goodness. That's quick. Something should be getting warm, if not hot with that much amperage draining from the battery. That's like leaving the lights on and even still, sometimes it would take longer than 2 hours then to completely drain a fully charged battery. You'll need to start unplugging things to see what's draining it. You'll need some type of amp meter connected between the negative battery cable and the negative post. (Cable disconnected) Be careful because it sounds like a lot of juice is being drained from the battery so a small, cheap amp meter will probably blow a fuse with that much amperage. Pull the power window fuses/circuit breakers, power lock fuses, etc. You can pull as many fuses as you like to start with. All at the same time. Just make a note of which fuse goes where. Once you get them out, reconnect the battery. Notice when you connect the cable, did it spark a lot or none at all? If it did a lot, there's still a drain. If not, leave it connected and start replacing the fuses, one at a time. Watch for sparks when you install each fuse. If one sparks a lot, that could possibly be the circuit at fault. I know this is kind of vague but it's a place to start. Try this and then repost. I'll do my best to help.