rear brake light/turn signal dont work

[95StangMan]

sometimes my driver side rear brake light/ turn signal dont work, sometimes they do. they light up when i use the keyless entry, and when i turn the lights on. any suggestions on what to check first? anyone with a similar problem? car is an 03 mach 1. thanks

 

[2BADSTANGS]

I'd start by checking the cheap/ dumb stuff, like the ground going to that light, the rest of the wiring and bulbs. If it's not that check your signal switch and wiring. If it's not that, I'm at a loss.