Vortec 5.7L 1997 GMC Sierra, Not charging

[OBE]

Clue: At the same time I noticed it not charging I also noticed that my DRL headlights aren't working.
I'm wondering what might knock out both circuits.
Clue #2: I started the truck and moved it out of the garage, up to the house to load it up. It was okay.
I shut it off and ran into the house but I left the key in the ignition. (because I'm always misplacing my keys)
As I opened the door the alarm sounded so I pulled the key half-way-out so the alarm would stop. It stopped and I left the key dangle there.
Could THAT have done something?
When I got back in the truck it started and I turned the headlight switch on because it was dark. But the alarm sounded as it does when you forget to shut the lights off and get out of the car. I thought, "That's peculiar! It's acting as if the motor isn't running."
That's when I looked at the amp gauge and saw it wasn't charging at all.

 

[ak diesel driver]

Low voltage can cause weird issues. I'd start with fixing the charging issue.

 

[OBE]

Hi ak diesel driver, we've talked before. You helped me get my 2000 6.5 3500 running. It used to shut off and wouldn't start for me. It turned out I had to replace all the wiring devices in my steering column. I sold it and broke even where before that I had a (valuable) unsellable hulk in my garage that I didn't need anymore and I couldn't sell. Anyway, this Sierra just stopped charging. It behaves like a fuse or something simply blew out.
I tested the positive battery cable for voltage TO the ALT and it's okay, so it's not a fusible link.
I already had a new battery which I have installed but it behaves the same. I can't help thinking those DRL headlights being OUT has something to do with it.
I have one of those cigarette lighter gauges but the ALT side doesn't light at all and the BATT side says the battery is BAD but this is a brand new battery.

 

[btfarm]

Have you pulled the negative battery cable while it's running? If it shuts down you likely have an alternator problem.

 

[MrMarty51]

Yeah, pop that alternator out of there. If You have an independent starter/alternator repair shop in your area, take it to them and have it tested.
If bad, see if they have one of their in house up rated alternators for You.

 

[Bob Foust]

I have a 95 Silverado and I am learning a lot quick because I have to, but back in the day you might want to look at your light switch. Chevrolet used to run the charge wire through the light switch so the headlights were getting the best posible voltage. But who knows now? My wife reminded me today that I don't know squat.

 

[OBE]

SOLVED! Several of the YouTube videos suggested fuse #4. I pulled it out and looked at it. It didn't LOOK blown! Mechanic "interviewed" me for clues to what I had done while "playing" with my truck, myself. I told him about the new camera setup I installed (which I love!)

He called me a half-hour later and said he checked it but that nothing was wrong with it. The truck is blowing-out fuse #4 every time he puts a new one in. "Did you do anything else involving wires or unbolting and rebolting any components? Otherwise, I'm going to have to trace all the wires in this circuit (involving pulling my dash apart) and the labor hours are going to get nasty!"

I told him that a year ago my rear-view mirror fell down after I put one of those sun screens in my windshield. It got so hot the mirror fell down (it was one of those heavy jobs with electronics in it) and it pulled the wires out of the headliner. At the time I merely bread-tied them and taped them in the corner of the windshield and rode around like that for over-a-year! But after I tucked-in all the wires for the cameras I thought "Let me do something more neat and permanent with these rear-view mirror wires."

I "tucked" them into the headliner (over the driver's left ear) and pushed them in with the little plastic tool they give you with the camera setup. Well...I shorted them out! He only charged me one-hour! Cheap!

 

[MrMarty51]

Well, thats getting off easy enough.