Upgrade third brake light- extra wires?

[dadbern]

I am preparing to upgrade my third brake light. The white connector in the pictures matches up with the new connector on the upgraded lamp. Does anyone have any idea what the additional red and black wire are for? On the existing lamp they connect to the red and black wire from the harness, I just don't know what they feed or are fed by. The schematics in my chilton are useless. These run down the back of the cab. I suspect I will have to jumper the into the harness for the new light. Any Input?

 

[diymirage]

i would guess (and thats all it is) the cargo light?

 

[dadbern]

I disconnected the harness and the cargo light did not come on, when I plugged it back in it did not. This rules out the cargo light. The additional wires have no connector, the just run straight into the truck. I was thinking maybe back power window, but it would not make sense to have the lights anfd the window on the same circuit.

 

[dadbern]

oops, when I plugged it back in it did come on