NegativeROG

Hello all. First post here. I have a 1995 C3500 Silverado, 6.5 Turbo, Crew Cab, RWD, 8' bed. I've replaced my driver's side tail/turn/reverse "circuit board"-type lamp assembly over half a dozen times in 2 years. No collision, never been hit, so that's out. The bulbs don't burn out, so when I buy a replacement (nearly $30 a pop), I can use the bulbs that came out of the truck. The brake light works, the reverse light works, but I have no turn signal/hazard, and have to stick my arm out the window to indicate left turns. I've talked to guys at parts stores, they usually only sell one of those assemblies after an accident, so I'm about the only one in town that has to buy them consistently. I've purchased the cheapies from Rock Auto, and they don't even last a week. The units I buy from O'Reilly's or Auto Zone give me a few months. I purchased the truck with a receiver and wiring already installed, and it looks like it was done at the dealer, not by a sloppy amateur in a hurry. This has been going on since I bought the truck in '03, but it's been really bad the past couple of years. Does anybody have a clue as to what could possibly be killing the circuit board? If anyone needs more info, I'll provide. Thanks for your time and help.