Ignition Wiring Issue, please help.

Sorry for asking so many questions, my first stabs at fixing a botched electrical system. I really appreciate all the help, learning a lot very quickly!!

Back to the original question too, I have found the red power lead behind the dash, it reads 12V when I connect it to the ground. When I connect it to the black lead it drops to 0V and I still don't get power to the car. When I attach the same black lead directly to the battery I get 12V and I get power to the car. Any thoughts on what might be wrong with the red power lead?