Okay this is what I did put a new steering wheel and turn signal controls (tilt, no cruse) in my 79 bronco. Thought all went well as I tested left and right turn signal they were good to go, thinking that meant brakes were good too. Pick up my friend going fishing when he notice I had no right brake light.
The left brake light works and both tail lights work both left & right turn signal work but no right brake light what up with that. I'm getting old so sending me to the right spot would be appreciated, thanks.

 

Replace the bulb. The filament for the brake light probably burnt off.

 

Gee I wish it was that simple, found a good wire diagram of the turn signal switch which show how power (constant 12 volts) from brake switch and power from the flasher (left & right blinker) is routed through the turn signal switch electrical contacts allowing the used of same set of wires and filament in tail light bulb to do both jobs, this I already new just didn't know how until now. I have another brand new turn signal switch that I order by mistake for Bronco with out tilt steering, electrical contacts our the same but different configuration on mounting base so won't work in my Bronco. Own my Bronco for twenty years now and never new that I had tilt steering LOL try pulling on your turn signal select arm you might get a surprise. Because of the tilt steering that I have the turn signal switch comes box with the electrical connector plug not connected so you can route wire harness through tilt steering housing first than insert wires in connector plug than finish plugging in under dash. Thinking this is where I made a mistake pushing a wire in wrong hole in connector plug. I did write down wires color and follow connecting new harness to connector plug. Raining hard had to quit tomorrow under cover will "ohm" out the turn signal switch at the connector plug hoping I just made a mistake if not turn signal switch must be bad guessing made in china.

 

Okay new day rain has stop, first I took the new turn signal switch that was for "no" tilt steering that won't mount up and at the bench tested it using ohm meter and function like it should as show in Schematic diagram. Compare wiring harness to new turn signal switch that I did install with tilt steering and all colors wires match up on connecter plug. So with this new knowledge I disconnected connecter plug under the dash feeding turn signal switch. With the turn signal in off center position using ohm meter I ohm between brake wire pin connection that route through turn signal switch contacts connecting left & right side tail lights for brakes, I had reading on left side tail light pin but open on right tail light pin connection in connector plug. This is not good both left & right should read through for brakes. Now when I connect ohm meter to flasher pin connect (turn signal) and select left turn I get reading on left tail light pin, select right turn I get reading on right tail light pin. I plug connector back under dash and power back up. Still no right brake light when applying brake with turn signal off in center position but I notice I do get right brake light when turn signal is in left position flashing which is the way it should work, "crazy" I feel this is a faulty switch I been had my those Chinese again.

 

It does sound like a faulty switch.