Chevrolet Repair: 1996 GMC Truck K1500 1/2ton P/U 4WD 5.0L SFI 8cyl, socket assembly, gmc truck

Question
right rear blinker and brake light does not work.  replaced bulb...still no luck.  i assumed it was not fuse, because left rear works just fine.  also, tail lights do work when headlights turned on.

Answer
HI JAROD, IF IT WERE A NEWER TRUCK IT WOULD BE FUSED, YOURS IS NOT. DO YOU HAVE A TEST LIGHT TO CK FOR VOLTAGE ?? THE TURN SIGNAL AND BRAKE LIGHT ARE ON THE SAME FILIMENT IN THE ONE BULB.
THATS WHY THE PARKING LIGHT WORKS,[DIFFERENT FILIMENT SAME BULB] THIS COULD BE SOMETHING AS SIMPLE AS A BAD SOCKET ASSEMBLY OR BAD GROUND TO THIS SIDE OF THE BULB. GET A TEST LIGHT AND CK FOR POWER AT THE WIRE GOING INTO THE SOCKET ASSEMBLY FOR THE BRAKE LIGHT OR SIGNAL,SEE IF IT HAS POWER THERE,IF SO THE SOCKET IS BAD.[[WHEN CHECKING FOR POWER MAKE SURE THE BRAKE PEDAL IS DEPRESSED]] IF NO POWER TO THIS POINT, GET UNDER THE TRUCK AND LOOK FOR THE WIRE HARNESS PLUG FOR THAT SIDE OF THE SOCKET. WILL BE THE SAME COLOR WIRE FROM THE SOCKET BACK TO THE HARNESS. THIS HARNESS PLUG WILL BE UNDER THE BUMPER AREA ALONG SIDE THE FRAME RAIL AREA. YOU SHOULD HAVE POWER HERE AT THIS POINT. IF YOU DO THEN SOMEPLACE BETWEEN THE PLUG AND THE LIGHT SOCKET THE WIRE IS OPENED. CK FOR ANY GREEN WIRES [CORRODED] OR BROKEN WIRE. DOES THIS TRUCK HAVE A TRAILER HOOK UP ??? IF SO CK THE WIRES VERY CAREFULLY WHERE THEY HOOKED THEM UP. WATER AND WIRES DO NOT MIX..LET ME NOW HOW YOU MAKE OUT..TOM.....