On most W-Body vehicles, the hazard and turn signal flasher is mounted below the steering column.
If the turn signal and/or hazard lamps do not work, first check the fuses. If one of the turn signal lamps goes on when the park lamps are turned on, check the front park/turn lamps on that side for an open or poor connection. If the turn lamps stay on (do not flash) in both turn left and turn right, replace the flasher.
For any of the following symptoms, replace the turn signal switch:
If the hazard lamps stay on but do not flash with the hazard switch ON, but the stoplamps operate normally, replace the turn/hazard flasher.
If the stoplamps do not turn OFF, adjust/replace the stoplamp switch.
If a turn signal indicator does not light but the turn signal works, check the bulb connection and wiring to the indicator.
If only one lamp does not operate, check the lamp socket and related wiring for opens and corrosion.
If one front park and/or marker lamp does not light, check that its ground is clean and tight.
If the park lamps do not turn OFF. Check the headlamp switch. If okay, look for a short to battery power in the wiring.
Check for improper installation of aftermarket equipment and accessories. For example, a poorly installed trailer towing light connector may affect the rest of the lighting system.