KE4HIE

I need help with my 2000 Silverado that the left side brake light will not work on the OEM trailer plug. All lights on the truck work properly. The problen is only with the drivers side brake light on the trailer plug? I have blinker and emergency flashers on BOTH sides of the trailer plug but only a right brake light. Being that mine is a 2000 model, it does not have the 10 pin module ( oem # 15764135) behind the fuse box. it has the tryco # EP-29 flasher module which I have replaced. No change, still no left brake light at trailer. All fuses under dash and under hood are good. Any suggestions? KE4HIE