74 chevelle electrical dead

[internic]

hey guys, i am trying to fix up a 74 chevelle malibu, and it can only be started if it is jumped, otherwise the battery goes dead very quickly. the battery is new, and i was trying to trace for a parasitic drain by putting a light bulb between the negative batt post and the negative batt terminal. with key to "off", light doesnt glow in the slightest, but if i turn it to on, the bulb glows brightly, even with alternator and ignition coil disconnected. should i pull fuses til the bulb goes out, or what is a good course of action, im not very experienced with old electrical systems... all input appreciated...thanks

[Blue Bowtie]

That's normal. Current flow will light the lamp, and it's due to more than just the alternator or ignition coil. The accessories are powered when the ignition is on. The alternator field is also energized, so if you didn't disconnect the two-wire field connector, that would be more current flow. Gauges and warning lamps are powered with the ignition on. As long as you don't park it overnight with the ignition on, the battery should maintain charge. You may want to have the battery load tested to be sure it is good, even though it is new.

[internic]

thanks blue blowtie. so an update, i pulled the fusebox and disconnected its 12" red lead from the positive bus on the engine bay firewall. i measured the resistance between that lead (i believe its the main fusebox +12 wire) and ground, and i get 30 ohms in all key positions. also, i noticed that if i jiggled the fusebox slightly, it would drop to 0 ohm. i then discovered that if i disconnected a connector at the fusebox that has two thick wires to it, one white and one black, it would not drop to 0 anymore.

i ended up tracing the 30 ohm resistance to the "tail" fuse/circuit, because if i pull that fuse the resistance goes back to infinite. any thoughts?

[alblogg]

Could your tail lites be grounding back through them selfs,instead of burning they are putting a dead ground on the battery. I worked on 18 wheel and car trailers that gets that problem some times where they are not grounded good or a wire melts into another one or a bulb gets twisted to far in the socket or put in wrong.

[internic]

i actually crawled into the trunk and unplugged the harness for all the tail/brake/backup/sidemarker lights and there is still a 30ohm resistance between fusebox hot and ground in all key positions, key in or out. im positive its the tail circuit, but the wire from the tail fuse runs up behind the headlamp switch and then to behind the speedometer?? unless its being routed through the turn signal switch, im confused, lol.

i studied the wiring diagrams for a few hours but could not figure out where that wire specifically goes to. I also could not figure out what the black/white harness is responsible for, because that appears to be responsible for a dead short if you jiggle the fuse box. i guess ill post if i figure anything further out.