GM-GMC: electrical, chevy blazer, fuse holder

Question
Have a chevy blazer that is having some kind of electrical problem that I can't figure out.  Changed alternator but something keeps draining the battery and even a new alternator will not charge the battery.   Should I test some kind of solenoid?  Help I'm losing my mind!  By the way this is an '85 blazer.

Answer
Make sure that you don't have a glove box light that stays on, or some other light (under hood light?) that can kill the battery if the vehicle sits for a period of time.

The battery can also be at fault.  Have it tested and verify that the new alternator is also working properly (bench test).  If they are okay, procced with the following steps.

How you test for the source of the electrical drain depends on your skill and/or patience:

The skillful way is to use an ammeter and, starting at the battery, look for current with everything shut off.  You then have to start isolating and testing individual circuits until the source of the drain is identified.

The more time-consuming way is to remove all the fuses from the fuse box and see if the battery stays charged.  Be sure and note what amperage fuse each fuse holder had installed (or consult the onwer's manual) so that you reinstall them in their proper place.

If the battery stays charged, one of the fused circuits is causing the problem.  You will have to replace the fuses, one at a time, and see if the battery stays charged.  When you find the circuit that is causing the drain, you have to find out what device is causing it.