New here guys n gals. I'll introduce myself in the appropriate section. Got some lighting issues that has caused several problems.

1996 Blazer 4Door with keyless entry. Original problems developed from a repetitive dead battery condition. Car parked overnight won't crank in the morning. Stranded my wife a couple times. Each time I could recharge the battery and she could be on her way. Did some checks with my DMM under the hood and suspected a failed diode section for the alternator. Took it to Autozone where they confirmed it both with a load tester and a bench test off the vehicle. Bought new alternator. Charging looked perfect. The next day dead again. This time the DMM read .15V on the battery. Dead short. Replaced the battery. Again checked everything and all was good. Parked and locked the car overnight. Before bed I looked out and noticed interior lights were on. When I locked it earlier I did check to see all inside lights were not on. So I opened/closed all doors/hatch. Lights went out. Came out to check it in the morning - lights on again. The only thing that has been fixed or changed on this in the last couple weeks - passenger front window switch replaced with AC Delco part. Driver door pin for the lights replaced with AC Delco part. I know the part works right because with the door open I can push the pin in and all lights turn off, both with ignition off and on. Last was the driver door window regulator wheels replaced. So regulator came out and put back in after repair. That's it. This problem with the lights turning on and off randomly has now started doing it with the car running. My wife said the lights just turn on and off at times while driving.

Fuse is pulled for interior lights for now. Battery is holding a charge just fine now, so I know it's in the lighting circuit that caused the battery and alternator to fail as they did. I'm leaning towards a short-to-ground or a bad interior lamp control module. I want this fixed but don't want to just throw parts at it. I don't have any good trouble trees or schematics to trace wires and check for voltage drops. I also don't have a scan tool. So I can't run full diagnostics like at the dealership.

Sorry for it being so long for my first post. Trying to minimize all the "did you do this or check this" questions if I list the obvious things I have done.

Any help?

 

What about the switch next to the steering wheel where you can manually turn on these lights, I believe it would be classified as the headlight switch. could be a short or bad contact within that switch.

 

My busted up door panel on the drivers door wouldn't press the switch correctly. Was an accidental repair that went along with just replacing the panel for the purpose of it needed the panel. (I actually got fed up with the light and let's say I have a few extra door jam switches and headlight switches)

 

The switch for the hatch glass is a common problem. Try wiggling the hatch and see if the lights flicker. Or disconnect the switch and see if the battery goes dead.

 

For some reason I was leaning that way too. I noted in the wiring diagrams that I located that there was one back there which I was unaware of. If this test reveals the tailgate switch is the fault, is this an easy replacement or does it come with the entire latch assembly?

 

Although this door panel has seen better days (hell, all the door panels have seen better days) the little grey plastic striker button in the panel is intact and the panel isn't warped or missing any of the retaining clips.

 

Did you ever figure out why your lights wouldn't turn off?

 

I apologize for not following up on this sooner. I know it sucks when a newbie comes on a forum, asks a bunch of questions and then doesn't let everyone know what the fix was if there was a fix it all. Turns out it was a problem with the door panel but it wasn't because the door panel was busted up. Apparently the age of the hinges for the door have allowed for the door to sag. So part of the door itself is hanging away from the body just enough so as to allow the pin to extend and light the lights with the door closed. I don't have the means to fix the hinges right at the moment so what I did is take the striker pin of the door panel and put a washer behind it. I found it by accident when I was in the car with all the doors closed. I had my wife hit all of the doors from the outside with her palm. When she got to the driver door, the lights went off and back on. So I tried from the inside by pushing on the door panel just slightly enough to set the lights off. So there you go. Maybe the lot of us should keep this solution for the next newbie. Start with the things that don't cost so much money first and then go after lighting modules and wiring problems. I appreciate all of the input on here. It gave me a direction to go. Luckily I just stumbled on an easier fix.