very strange electrical issue,
 

very strange electrical issue, i have an 86 k20 burb 5.7. First instance after sitting in the driveway for 2 months being periodically ran for about 20 mins a week. So today I started it up ran it for a few minutes shut it off installed a new dash speaker and a capacitor to the sound system. Everything with the sound system except for the head unit is on a circuit breaker that was turned off. So I went to start the truck back up and, I got lights and the buzzing noise. The ignition clicked once and all electrical was gone. So I attempted to jump start the battery thinking I had killed the battery from charging the capacitor, But jumping the battery had no affect. So I went and got a multimeter and checked the battery directly about 3 hours after it wouldnt take the jump. The multimeter read 12.6??!!!! I looked into the truck and all the lights were on, so I jumped in and tried to start it, all electrical shut off and would not come back on. What the hell is going on?!! :smoke:

Re: very strange electrical issue,
 

Clean your battery terminals.

Re: very strange electrical issue,
 

And your ground to the motor from the battery.

Re: very strange electrical issue,
 

Problem solved, cleaned all grounds from battery to everything it was grounded to, only one question left, Where is my chassis to frame ground on this truck?

Re: very strange electrical issue,
 

I have one that goes from my engine block to the firewall...then from the firewall to the frame.