Hoping you can help...

I have a '69 Camaro that has an electrical issue I can't find.
I connect the battery and have power (13 volts), all electrical inside
the works. As soon as I turn the Ignition Key I lose everything.
If I check the voltage, I have 13 volts at the bettery terminal, but only have 3 volts at the horn relay, and the positve on the alternator.
If I disconnect the battery, and reconnect, I have power again. Sometimes the car starts and everything works fine. I can shut off the Ignition, and try to restart I may have power, or I may not. It seems like disconnecting the battery resets everything.

I have a new battery, cleaned the terminals, new alternator, new horn relay, and new voltage regulator.

Any suggestions???

 

Sounds like a grounding issue, kind of a pain, but if you have an ohmmeter you can poke around and see if there are any loose ends-parts where maybe things have rubbed raw over the years and are grounding out.

Have you checked your ignition switch? Also check the other ends of the battery terminals, particularly your positive terminal to the starter.