A good way to check if you dont have a clue what it is.... Disconnect your negative cable and see what the voltage is between the cable and the negative terminal. If you have a reading with the doors shut, and everything off. It should be very very very close to 0. If you have an alarm or something it will be a little higher.
For example... I had a bad capasitor inside my head unit in my truck that was brand new. In 2 days it would **** my 1000 CCA battery, dead as a doornail, wouldn't even jump. Charged it up, and it was ok for a while. If I didn't drive it for a couple of days, it was dead again. Charged it back up, and then I started keeping records. I pulled the fuse for my interior lights, knowing I'll leave that door open to test... Then got some long peices of wire to use for my meter. Tied one around the cable, one around the post, and hooked those up to my meter which was inside the truck at this point. Kept pulling fuses until I seen the change, and sure enough when I pulled the radio fuse, it dropped back to 0. Now I'm sure where the problem is, pulled the power to the radio, and swapped it out, and havent had a problem since.
I would think you could do the same thing with yours. But its had to say at this point. Did you have all the right cables? Or did you have to make one? I'm about to remove mine.. well its removed and I'm trying to see if I can't fix it, but I'm going to have to swap my changer out or something, and I'm curious how that slave unit works out. Looks like you have a 91 + ? For some reason I can't remember what radio I had in my plus.. lol its escaping me at the moment.
