Help with taillights?

[Chip]

On my 85 F-150 my tail lights don't work. The brake lights and turn signals are ok. I have checked for the wiring harness and can't seem to find any damage to it. Could it be the switch that is bad even though the head lights work?

 

[Chip]

Duh!!!!
dummy me it was a fuse. I thought that the turn signals and brake lights would be part of the same circuit. Thats why I thought the problem may have been elsewhere. For a person with a degree in electonics engineering I really feal like a ****head. My wife said she would have checked the fuses first, but I thought it may have been a little more technical. Eric if you want to save me the embarassment you can delete this thread. I guess I know why I like landscaping so much not so technical.