This is a long story but I will sum it up the best I can. I've been a doorway member for a while now.
Changed all the gaskets in my 2000 blazer 4.3 I was putting it all back togegher when a combination of rushing, complacency and being tired got the best of me. I put the battery in but forgot the alternator hot wire. No big deal started putting it on when I hit my socket on some metal and grounded it out. Get it on go to the cab, put the key in the ignition and nothing but the radio comes on. Started doing simple diagnostics. Put a DMM to the battery, alternator, starter, and fuse box. All have the correct voltage (12.43), so I grab the test light and DMM again to go to the fuses. None of my underwood fuses are working EXCEPT for Ign A, IGN B, IGN C, TBC and Ecm b. Everything else is reading no voltage (fuses are good, checked physically and by continuity test). I'm at a dead end. Idk where to turn anymore. Leaning towards the ECU or the TBC but I don't want to throw money chasing dragons. I'm 99.9% sure all grounds are perfect and I didn't miss anything. The only thing I did to rectify this problem was change the main fuse and check the inline fuse at the starter, but since the starter is reading the same as battery I would assume I don't have to check the inline fuse. Any help is GREATLY appreciated. I used 2 vacation days (today and tomorrow) just to get this sorted out.

 

Unbolt the under hood fuse panel and check the bottom where the wires connect. Sometimes they burn up but appear fine from the top. Disconnect the negative battery cable first.

 

Newbie and can;tfigure out how to post

 

Underneath the battery tray is a 150A Megafuse. It likely popped.

 

I got that problem taken care of (the fuse box was loose underneath. Tightened it up and she fired right up. Ended up changing the plugs and wires while I had it apart. Fired it up and it ran like **** (out of time) retired it and it ran better but still jumpy on the throttle response (retimed again) not it is a steady idle but as soon as I go to take off it gets a little jumpy and smooths back out. Maybe a dumb question but can you still use a timing light or something similar to check the time? Also it idles a little rough when it rains. And last thing when I arced the hit wire my gauges suddenly half way work. Battery light, low fuel, brake, abs, security and CEL stay lit up like a Christmas tree, and the fuel and temperature gauges don't work. I've checked fuses all are fine. Thanks for the help again. Been covered up at work the past few days so I'll reply as quick as I can.