Bed/cap lights inside

Hi everyone I have these leads coming out of the bed side with fuses in line. They plug into the cap for what lookl like 3rd brake light and a interior light in the cap

I have new lights for inside but don't seem to have power in the wires? My manual hasn't showed up yet so I'm not sure where the power comes from to check them properly. Any help would be great

 

Are you checking voltage static or are you turning headlights/parking lights on with key in IGN ON position !

 

I have the same harness for my cap. That's a pretty standard aftermarket set-up used by truck cap dealers.

Pop your left side tail light off (two bolts). You should see a power tap into the brake light wire. The line for the interior light probably runs up to the front of the truck to get its power. could be switched or un-switched depending on what the customer wanted.

 

When I install caps on my trucks I always remove that standard connector and install a trailer style connector. On my Tundra I also installed a 12V outlet. On the power wire for the lights you also want to install the fuse at the battery connection to protect the whole length of the wire.

 

Ok thanks everyone! So an important step to note is making sure your multimeter doesn't have a blown fuse! It turns one but doesn't measure anything!

So I like the idea of the trailer plug! So if I wanted a constant 12v to the bed I need to run a line to the bed?

 

Yes, run a 12 or 10gauge wire with a waterproof fuse holder from the positive he post to the bed. The ground wire can be connected at the rear of the truck and the brake light wire can be tapped into the tail light like was explained by tvpierce.

 

Perfect thanks. I'm going to find a panel for the power outlet and to switch for the lights.

I found the power for the 3rd brake light in the harness pictured. It was much easier after fixing the meter

 

A few suggestions:

The fuses are kind of useless there. The point of a fuse is to protect the wiring. The fuse for the third brake light should be right at the junction where it taps into the left brake light.
The fuse for the interior light should be up at the source -- to protect the wire that runs the length of the truck.

Also, I'd put a grommet on the hole where the wires come out. That will protect the wire from chafing. You can get one at any auto parts store. Just measure the hole and tell the guy/gal behind the counter what you're looking for.

 

Yep the whole thing is being redone with a new 12v power line run back.