Ok, I have purchased a camper shell from my neighbor's nephew. He showed me the brake light worked and also his cargo light. My truck did not have a cable harness to connect to the camper's brake light and he explained to run a cable for the cargo light inside the shell. Right... I spend the weekend running a cable for the cargo light and it works... good. Now, I run a separate cable for the shell's brake light. All is good and working correctly... for a day. Here's what's going on...

I connected a +12VDC wire to the brake switch harness. Located the correct wire, and spliced into it. I was able to visually verify the brake light did work, saw it working as it was dark. The next day, It didn't work. Almost like the bulbs blew. Both are good. Even bought new ones to make sure...nothing. Checked for power, and it is present... all the way to the socket. There doesn't seem to be any short. Wires are dressed and neatly displayed. No chafed or broken insulation, skinning or otherwise. As soon as I connect a bulb to the socket, all power is gone. I have checked my wiring and it is correct, hell, it's only two wires. So I thought I would stick the common to chassis ground... no difference. WTF!?! As soon as something is connected to that socket, power disappears. Both sides are separated but it acts like something it grounding the +12VDC as soon as something is connected to it. My truck's parking, brake, reverse lights work fine.

Any ideas? Oh yeah, cargo light works. No problems at all.

 

If you're still having an issue I would make my connections at the rear brake light assembly. Just run the two wires from the shell's brakelight to the vehicles brake light assembly and make you positive connection at the brake light socket and your ground can be the chassis or in some cases there will be a ground wire for the tail/brake lights you can utilize.

 

Yeah, I saw somewhere there is a 'logic box' to correct the blinking issue when tapping into the brake lights. I though I would be clever if I did that. I have the single brake/turn light. It would be so much easier to get the thing to work if I had separate brake/turn signals. DAMN! I guess I have a quest now. Hopefully it works, or I'll be right back to where I am! Thanks!