Technical Dead battery - power draw question

I've been trying to trace down a power draw that's causing me a dead battery (pretty quickly).

To trace the draw, I am putting a test light between the negative cable and battery post. Needless to say, the light is lit.

I have removed every fuse and the light remains lit.

I'm at a loss on how to proceed further. Any suggestions?

(Its a Rebel Wire harness that I installed.)

 

Maybe an alternator diode.

 

To see if it's the alternator, disconnect the big wire from the alternator screw terminal, and try the light test again.

Another possibility is the horn circuit, unless there's a fuse for it....GM didn't use a fuse

 

Thanks.

I disconnected the alternator completely. The light remains lit. I even pulled each fuse with the Alt disconnected (thinking maybe I had two shorts). No change.

 

Is there a fuse for the headlight switch?

 

Long shot but years ago I worked in the truck shop at a dairy and after chasing shorts as described above with no luck we sometimes found the short was between the battery case and the battery box. You never know.

 

Yes. Its one of the ones I pulled. Its a 56 F100. I have an original style headlight switch. The only fuse on it is for the dome light.....

So I just pulled it. BAMMMM. That did it.

Thank you for jarring my memory!!!

 

I'm chasing the same problem now. Done the same tests you did. Will try taking alternator wire off and then testing as suggested above.. I will be following this thread and will let you know what I learn.

 

Take your multimeter and test across the top of the case putting the + lead on the + post and use the - lead to check around on top of the battery. If it is spotlessly clean it won't be an issue but a dirty and maybe a bit damp battery can have a huge draw though all that dirt and moisture. I've seen one battery that would go dead in two hours because it had a 9+ volt draw across the top of the battery.

One other battery draw that another student had on his 64 lowrider, he left it parked at home because he didn't want it banged up in the parking lot where he worked and every morning his battery was dead. after fussing with it for days his mother says "Oh, you brother and his friends play your car stereo every night when you are at work. Brother got a good ragging out and problem solved.

 

Unplug the back of the ignition switch

Also try the horn relay!
They are usually live and ground via the horn button .