1994 Ford F-150 Brake lights

Electrical problem
1994 Ford F-150 V8 Front Wheel Drive Automatic

Alright so my boyfriend and i have a brake light problem and we were wondering how to fix it. Our front lights work when we pull the light switch no problem. However our rear lights do not. We had a friend of the family who is a mechanic take a look and he suggested that the issue was a switch issue. He rigged it up so that if we connect a little wire from one of the middle wires and connect it to the main 12volt wire then our rear lights work. We replaced the switch part, the item called a switch/commutateur interruptor like he suggested but that dose not seem to be the problem as we still have to use the wire rig that he set up to get our rear lights to work. My boyfriend thinks the problem is a wire issue so i was wondering how we should go about trying to fix it. If its fixable, or if we should take it to a mechanic. One of my boyfriends uncles said that he had a similar problem with his own truck and he couldnt figure out what the problem was and instead traded his truck in. It was also mentioned that our particular truck is know to have this unexplainable light problem so any suggestions would be helpful. The dome light also works fine. as do the dash lights but only when we have the brake lights rigged. You can find pictures of the rig and the part we replaced at the link below.

http://s389.photobucket.com/albums/oo331/tsinganisoul85/The%20Truck/