Hi All
I know this is an old Post but I had the Same Issue on my 2002 Silverado 1500 HD, Hooked my Wife's Horse Trailer up to my Truck last Fall and No Right Brake Light on the Trailer. Everything else Worked, Parking, Turn - Both and the Left Stop light.
I rented a U-Haul Trailer to take my 69 Camaro to a Show, Same thing, No Right Stop Light, Everything else worked Great.
Today I first Replaced the Flasher $ 9.00, Didn't work, Read this Blog and decided to Test my Fusses again with a Piece of wood between the Seat and Brake Pedal, Keeps the Brake lights on, Turned on the Ignition and put the Flashers on, Fuse # 9 was burnt out ! ???
I did not pay allot of attention to those fusses as the Turn Signals Both worked on the Trailer.
Replaced # 9 Fuse with a 10 Amp Fuse and the 3:00 O'Clock Terminal in the Truck side of the Trailer Connect Plug is now Hot/ 12 volts which is the Brake !
All Set !
Timmy