I would like to wire my cap light to the 7-way power feed. Does anyone know which wire I could tap? I really do not want to tap into parking lights and have to turn those on to power the cap dome light, and if possible not wire a hot feed from the battery.
Thanks!

 

I take it this means the 7 pin trailer tow adapter.

If so, there is nothing direct to the battery.

You could remove the battery charge relay and jumper the normally open contacts to make it this, but if you ever put a trailer on with a brake battery, you will need to remember to remove the jumper and put the relay back in.

red line is the jumper when looking into the relay socket ( orientate the picture to the way the relay is installed in the fuse panel ).



This will change the trailer tow battery circuit to hot all the time.


That is the only way short of running your own wire to get what you want.
If you do not care if the circuit is only hot in the run position, then just hook it right to the battery charge circuit.

 

Why would you need a light in the cap when the park lights AREN'T on? If you jumper the BAT relay or wire straight to the battery, the cap light could kill the battery. In any case, remember to put a SMALL fuse in your new circuit as close as possible to wherever you tap the truck's wiring.