sounds to me it would be where the headlights and the brake light both draw their power, maybe trace it down from the headlight switch.

 

That's what I'm thinking I'm all so going to disconnect the harnnes connector big one by driver side wheel and power it there to see if the short is from there back. But it's snowing right so it will have to wait.

 

Good plan, that will help you isolate the problem.

 

Just wanted to say HAPPY THANKSGIVING. I'll get back on the truck after the holiday.

 

Ok now I'm back on working on the truck I changed my plan a bit (I'm not very familiar with a multimeter)instead of running power to the connector by front wheel. I put the multimeter on the ohms setting that beeps when you touch them. I unplugged that big connector and tested it black to ground red to the power wires and it beeps (I'm assuming that means those wires are touching somewere) then I un plugged the tail light and revers light conecter in the back. Tested the side that would go too the big connector no beep. Tested the side that has the sockets and bulbs it beeps. The reverse light socket does not beep. I remove the brake light bulb and it didn't beep when I tested again sooo I'm assuming it's the tail light socket.I tested the passenger and same thing it beeps when the bulb is in. Now I tried two different bulbs and it beeps when ether bulb is in. I'm not sure if it's the bulbs or socket......I'm going to go buy new bulbs and try them.

 

The beep is just testing for continuity between the two wires you are playing with. With the bulb in place, you will indeed have continuity between the power feed, and ground wire. Pull the bulb out though, and it breaks the circuit, so, no beep.