check hazard switch, hazard/signal relay, turn signal switch and/or "combination light switch"). I'm going through drivers side turn signal/parking light technical diff. myself. Previous owner murdered the wiring under drivers side fender, totally mutilated wires. The bulb sockets could also not be grounding properly and each side has it's own harness ground which is connected above your front right/left fender. before you do all this "checking" make sure your fuses are all good. Cleans out your sockets because over the years they get dirt and grime build up and electric corrosion. When you plug the bulbs back in use die-electric grease ($1.00 for little pack @auto store) on the connection points. We should use this on every electrical connection on our cars it prevents moisture and premature connection failure. sorry for the long write up, hope this helps. The helms bible has relay and switch trouble shooting and I'm pretty sure I downloaded the helms manual from this site. good luck p.s. do you have an aftermarket alarm?