first off its a 70 malibu 350, 4bbl. The wiring is a pretty big hack job, new alternator and new battery 3 weeks ago.

So after I let my car sit for a day or two, with the battery unplugged, then I turn it on it starts fine. Then I try to turn the headlights on and the whole car shuts off. It loses all power to the dash because if I set some radio presets before I try to turn the lights on they will be gone after the car dies. Almost always it is the headlights that I try first, but one time it turned off after I touched the brake pedal enough to turn those lights on too. I pulled the headlight connector to see if maybe it was the switch itself, but when I jumper a wire to turn the lights on it kills the car too. So after awhile of restarting the car and trying to get the lights to turn on, they will just come on without killing the car, and then I can turn them on and off as much as I feel like.

what could be going on here? What circuit is wired to the external lights that could be killing the whole car? and losing all battery connection to the dash?
any ideas

Thanks

I think I would probably start by checking for bad connection(s) at the bulk head connector.

It sounds like a very common ground problem. Older cars like ours have a tendency to become ungrounded at certain points due to condensation. First check both ends of the battery ground cable. If the non-battery end looks a little suspicious sand down the battery connector and the area where it grounds to. Be sure to apply a light coat of dielecric grease to the connector and hardware when you reattach it to prevent this from happening again in the future. Also check the headlight ground wires and do the same thing on these. This should fix you up.

where are the headlight ground wires? I will check the block ground on the battery to see if that is ok too.

Thanks

what could be going on here? What circuit is wired to the external lights that could be killing the whole car? and losing all battery connection to the dash?
any ideas

Thanks

Check all connections from battery to dash (battery, junction block, horn relay, bulkhead connector)

http://www.chevelles.com/showroom/data/500/medium/Original_Chevy_system.jpg