I have a 1999 f250 SD I purchased it used and it has a leer cap on it inside it has a light for the inside and the third brake light the wirers to the bed light are pulled out and wrapped around it I would like to know if anyone has wiring diagram or knows what they should be wired to it also has a four prong trailer harness in bed near tail gate would this be for that it does have 2 near the hitch
thanks mike

 

I have a pre owned 99 with a leer topper too. My topper had a battery powered interior light (it sucked, so I replaced it with a 50 watt tractor light straight off the battery). I'd start by checking for batteries, as most leer toppers have a battery powered interior light.

As for the tail light, the installer sliced into the black wire on the left tail light and grounded the second wire to the frame. It is easy to access the tail light wire by removing the tail light assembly. Removing the tail light also gives easy access to running the wires through the stake pocket into the bed of the truck. You can also do a simple check with a test light to make sure that your truck's black wire on the drivers side is the brake light (I presume yours is the same, but I could be wrong)

If I remember right, a four prong has a ground, running lights, left turn/brake, and right turn/brake. If you splice into the running lights, the third brake light on the topper will be on any time the headlights/running lights are on. If you splice into the either of the turn/brake wires, the third brake light on the topper will flashing when you have the turn signal on.