i have a battery drain i have done the volt meter between the neg. battery post and neg cable and tried popping out one fuse at atime but no help . i popped all the fuses out and still had power flow between neg. post and cable whats next? i really need help! thanks ,john

If you have a one wire alternator, try unplugging it and check then. Some of these get the wiring reversed and put a draw on the battery.

Also the wiring along the frame rails will rub the insulation off and cause a draw.

What year of truck are you working on?

if you can tell us how much current (amperage) is being used I can help a little more.

Weird I'm having this exact same problem in my 77 c10. I have a 3 wire internally regulated alternator that is brand new .. and a new battery. I went by a battery auto electric shop near my house and the guy measured a key off drain of .40milliamps - .025 is the max from what I understand. I did exactly as you did .. removed all fuses .. and still getting a draw. I don't have a horn on my steering wheel .. found the relay and removed that as well. Still getting a draw. There is a lot grunge on the main firewall electrical connection that one poster said was causing his problems. So I'm going to clean that. I really don't want to pay someone to find it .. but it's driving me crazy because I can't.

Did you disconnect all the wires from the alt? A short in a diode will cause a slight drain even on a rebuilt unit.