Help Please!

I have a 2001 Monte Carlo.  I bought it brand new in October of 2000 and it now has 122,000 miles. 

Recently it started something new and I am stumped.  Being a female, if I go to a mechanic and explain what is happening, I am sure whatever is wrong with it will cost way more than necessary.  It happened not too long ago with an exhaust problem.  I took it to the local repair shop and they quoted me $500 for a whole new exhaust system.  I couldn't believe it!  I happened to see an old friend that works on cars and asked him about it.  He sent me to the shop he patronizes and that mechanic said it would cost $40.  Yes, $40.  He stated all I needed was a new pipe.  I asked about the muffler and he stated the muffler is stainless steal, it is fine and doesn't need replacing.  He replaced the pipe, took my $40 and I haven't heard a peep from my exhaust, a year later!!!!

Sorry to get lost on that tangent but it is so frustrating!  Anyways, while driving the security light will go on and stay on.  After being on for a few minutes, the battery light will flash accompanied with 4 chimes and then go back to the security light.  The longer I drive, the more the battery will try and conserve itself.  The radio will go off and lock, a/c won't work, etc.  I have researched this and found it could be either the ignition control or the body control module.  Or maybe I could get lucky and it is just a fuse???

Has anyone had any experience with this problem?  I cannot afford to fix one thing to find out it was something else.  From what I read, the mechanics are not always aware of the proper solution.  I am almost certain it has to do with the passlock system and am willing to just disengage it for now if it would solve the problem.

If anyone has experienced this, please throw some clues out my way.  I am getting frustrated with this car!