Make sure you have power to the wires out of the switch and then make sure you have power at the bulb socket. My guess is if you have it in the front but not in the rear there is something messed up in the middle. Corrosion, a break. Thats where I would go if I determined the fuse, switch, and bulbs were good.
turn and tail work, the 4 ways don't and I can't find the flasher to replace it, the book says it should be behind the fuse block or on the right side of the instrument cluster, but I'll be damm if I can find it.
Well, in my truck the flasher for the four-ways is on the passenger side, behind the glovebox, on the right side.
Also, on my truck I would have an intermittent brake problem. Sometimes one would work, sometimes not. It was a mess. I replaced the turn signal switch (brake lights that function as turn signals also run through the t/s switch) and it worked fine.