third brake light is not working on my 2006 f-150

 

are the stop / turn lamps are working ?
If so, did you try changing the bulb ?

 

Yea, All other lights are working-I replaced the bulbs but third brake light is still not operating- What fuse controls this light?

 

Same fuse as the stop / turn lamps on the bed, this is the reason I asked.

Did you check the socket for damage ?

Take a meter, and test the CHMSL at the connector under the headliner ( should be able to see it from the CHMSL opening, might need to pull the liner down to get to it.