Help please:Electrical system not working at all
 

My car started acting funny about a month ago. It would not always start when I turned the key, and to start it I would have to turn off everything electrical(including taking the face off of my headunit), and wait for a couple of seconds before trying again. Well, I had just replaced the starter about a year ago, so I thought it might be the alternator that was the problem. I took it to advanced auto parts and they checked it and said it was fine. I then did Kevin Landers' grounding tutorial (everything except the starter, couldn't find cable long enough at first), and it was fine for a while then started doing the same thing as before. I later did the starter too, and once again, it was fine for a while, but it recently started doing the same thing again. Tonight I went to start my car and when i turned the key, everything electrical went on briefly then all cut off (even the lights in the doors.) It is now permanently off, I can only see a very faint light from my door light, and my aftermarket alarm system's led. I think it may just be a fuse that blew but I'm not sure, any suggestions on what to do or thoughts would be greatly appreciated. Thanks.
BTW, I'm not sure if this will help, but it's a 91' s5.

Well, have you checked the battery? Maybe I missed that in your description of the problem. Other things to check. Battery connections, ground connections, wiring harness, ignition switch. Better yet, download a copy of the factory service manual from one of the links in the 2nd gen FAQ and work through the troubleshooting matrix.

dead battery

Hey thanks icemark, I was thinking that until I went outside today and all of a sudden all of my lights came on and it just wouldn't crank. I saw an abnormal amount of corrosion on the negative post of my battery and sanded it off and my car started fine. Does anyone know what would cause this excessive amount of corrosion(the connection to the negative post is very tight.

It actually just did the same thing again today. Before I went out i reconnected my alarm system and put some dielectric grease over the terminal posts and their connections. I just disconnected my alarm and wiped the grease off off the terminals while moving the negative battery cable and my car started fine. I have noticed however, that my cars voltage is in the 13's when I start up now and low 14's after I drive for a second, it used to run in the high 14's. Does anyone know a possible cause? I'm thinking its soemthing with the alarm.