I bought a 97 F350 that I am turning into a dump truck. I am trying to figure out the wiring for the rear lights. I have all of the wires figured out but I have an issue. If you turn the key on I get 8 volts running through the brake light wires. I originally thought maybe turn signal switch or brake light switch but I unhooked both of them and I still get 8 volts through the brake light only wires but not through the brake/turn signal wires. I don't know where to look next anybody have any ideas?