engine and drivetrain Battery Drain

[Tmta]

My 1975 02 had been running great until about a month ago.  Went out to start it and the battery was dead.  I ended up taking the car in to a shop and had the alternator tested, was not charging.  I was also told there was a drain coming off of the #5or #6 fuse circuit.  My reverse lights were not working so figured that could be the problem.  I replaced the reverse switch and confirm my transmission fluid was still full.  My battery is still draining. After I turn the car off a red "L" warnings light comes on the dash.   I first thought it had to do with battery being low, but even after putting in the new battery it came on.  Does that light indicate a low fluid level?  Would that warning light have a large enough pull to drain the battery in a short amount of time?

 

Tom

 

 

[Tmta]

Sorry, thought I had this under electrical.  don't know how I got it tagged with racing.

[Simeon]

Does the 'L' light, which is the alternator charging light by the way, stay on when the ignition key is turned off?

[Tmta]

Yes.   I just replaced the volatage regulator and it is still on.  Could it be a bad alternator?

[Simeon]

Yes it could be. There is a good simplified diagram of the charging system on here (I can't find anything with the new layout). Maybe someone who knows the new site better than me can find it?