Some information first:

2008 Chevrolet Silverado 1500
Reg. Cab Short bed
4.3L V6 4x4

aftermarket car play radio installed almost 4 years ago no problems works great

2 10” subs installed behind seats. sound great feel great but I’ve unpowered the amp to get rid of it as a variable.

alternator replaced about 2 years back. Old one had a bad voltage regulator. (Vehicle lights flickered when alternator was charging just weird erratic voltage issues) I replaced the old unit with a higher output unit to support the subs. Possible
culprit?

The issue:

Random and total loss of electrical power. This first happened to me a few months back in the parking lot at work. Tried to fire up the truck no power whatsoever. No dash, nothing. I pop the hood wiggle the terminals and battery cables and go back in and fires up like nothing ever happened. Cool I take a short drive to the squadron. Get there no issues but when I go to leave truck it dies in the parking lot. Same story wiggle **** and it started again just fine. This same course of events has happened about 8 times over the course of 5 months. Be it in a parking lot or on I-35 or a back country *** road at midnight. You can sometimes predict it because usually the radio will start losing power then you lose everything. The second to most recent event was probably the most interesting because it didn’t want to revive at all. I had to troubleshoot it over the phone and get my gf to bypass the (old) megafuse with a pair of jumper cables to get it home. Very fun process.. not. I had her replace it and it was doing good and then it **** out again just today.

What I’ve done so far:

> Cleaned battery terminals and terminal connectors.
> Replaced battery with an optima red top. (had it gathering dust in my decommissioned Tahoe)
> Cleaned EVERY ground in the engine bay.
> Added a block to frame ground (shot in the dark ik)
> Replaced the 175 Amp Mega fuse located on the firewall.
> installed voltmeter in the cab. Voltage seems great I get 14.5 volts when charging.

What I plan to do:

> Try a different alternator.
> Replace battery cables. (This might be a longshot but I’m getting desperate)
> Make more grounds
> Try a different battery again
> Inspect PCM connectors. Maybe loose or potential corrosion.
> Truly Delve into wiring diagrams and try to find a potential culprit.

I will try all these things in about 2 weeks when I get back home from Florida. I just wanted to start a thread now and get some insight or advice to help me figure this issue out.

I appreciate your attention and your time taken to read this. Any insight is greatly appreciated. I am getting desperate and angry with this truck. Has anybody had similar issues? I can’t be the only one with an electrically challenged 08 Chevy lol.

Feel free to ask any questions.

-Beaty