1999 blazer intermittant no start

I just got this 4 door / 4.3l / auto trans / 4x4 blazer and there are two issues with it and they may or may not be related. The seller said it needed a battery but was starting fine but before I could check it out it did not start. I replaced the battery and noticed when I hooked up the positive cable it sparked moderatly. Ran it home and parked overnight. I would not start in the morning so I hooked up my charger and it would not charge. so I unhooked the battery and charged it to 12.2v. reattached the cables and it went right down to 8.7v. I unhooked the alternator to see if it was drawing-no change. I removed the starter relay-no change. I then removed under hood fuse cover, removed the first maxi fuse and the draw stopped. I reinstalled the first maxi and it then would start and run. I found the fuse for the interior lights was not there, installed a 10A fuse and the lights came on. so I removed the upper console, checked all the wiring i could see, and wiggle tested all the harnesses i could. 4-5 days later, after a short run from the house it would not start, so i opened the hood, unhooked the positive battery cable and the draw was evident. I removed the first maxi and reinstalled, again the draw was gone. reattached the battery cables and drove it since (about 5 days). the other issue it the turn signal flasher / combo relay behind the glove box clicks randomly when the t/s are not in use. I can wiggle the t/s switch and duplicate the problem so it seems the switch is too sensitive and cannot handle the weight of itself mayhaps. There is also an intermittant 1-2 second buzzing sound eminating from the rh dash as well.

I just got this 4 door / 4.3l / auto trans / 4x4 blazer and there are two issues with it and they may or may not be related. The seller said it needed a battery but was starting fine but before I could check it out it did not start. I replaced the battery and noticed when I hooked up the positive cable it sparked moderatly. Ran it home and parked overnight. I would not start in the morning so I hooked up my charger and it would not charge. so I unhooked the battery and charged it to 12.2v. reattached the cables and it went right down to 8.7v. I unhooked the alternator to see if it was drawing-no change. I removed the starter relay-no change. I then removed under hood fuse cover, removed the first maxi fuse and the draw stopped. I reinstalled the first maxi and it then would start and run. I found the fuse for the interior lights was not there, installed a 10A fuse and the lights came on. so I removed the upper console, checked all the wiring i could see, and wiggle tested all the harnesses i could. 4-5 days later, after a short run from the house it would not start, so i opened the hood, unhooked the positive battery cable and the draw was evident. I removed the first maxi and reinstalled, again the draw was gone. reattached the battery cables and drove it since (about 5 days). the other issue it the turn signal flasher / combo relay behind the glove box clicks randomly when the t/s are not in use. I can wiggle the t/s switch and duplicate the problem so it seems the switch is too sensitive and cannot handle the weight of itself mayhaps. There is also an intermittant 1-2 second buzzing sound eminating from the rh dash as well.

Sounds like the old battery might have been good, for starters... (no pun intended). You have to do diagnostics, unless you're rich. I KNOW that hundreds of batteries are sold daily in this country to replace perfectly good batteries. :headshake

You need an ammeter. Disconnect the battery positive, and connect the ammeter to the battery (+), and the other ammeter probe to the (+) battery cable. Key off. Check the current, pull a fuse, check the ammeter, and continue, until you find the draw circuit.

Then comes the hard part. Follow the circuit - literally, until you find the short to ground.

Multiple paragraphs are allowed in posts. Makes for easier reading YUP.