* Bulbs: The most common cause. A burnt-out bulb or a bulb with a weak filament can cause the flasher to act erratically or not at all. Check all the front and rear turn signal bulbs, as well as the hazard lights bulbs. A bad bulb in one location can sometimes affect the entire system.
* Flasher Relay: The flasher relay is a small electrical component that controls the blinking rate of the turn signals. A failing flasher relay can cause intermittent flashing or no flashing at all. This is a relatively inexpensive and easy part to replace.
* Turn Signal Switch: The stalk that you use to activate the turn signals can wear out internally. This is a more involved replacement, but a common failure point.
* Wiring Issues: Corrosion, broken wires, or loose connections in the wiring harness can interrupt the electrical signal to the bulbs or flasher relay. This often requires tracing the wires to find the break or corrosion. Common locations to check are near the steering column and the taillights.
* Multi-Function Switch (MFS): This is a more complex component that incorporates the turn signals, wipers, and sometimes other functions. A faulty MFS can cause intermittent problems with multiple systems, not just the turn signals. This is a more costly repair.
* Grounding Issues: A poor ground connection can prevent the proper flow of electricity, leading to intermittent operation. Check the ground points for corrosion or looseness.
* Body Control Module (BCM): In some cases, a faulty BCM can contribute to electrical problems, including turn signal malfunctions. This is a less likely cause, but should be considered if other components have been ruled out.
Troubleshooting Steps:
1. Check the bulbs: This is the easiest and cheapest thing to do first.
2. Check the fuses: Make sure the turn signal fuses haven't blown.
3. Test the flasher relay: This is often located under the dash or in the fuse box. You might be able to hear a clicking sound from a bad relay.
4. Inspect the wiring: Look for any visible damage, corrosion, or loose connections.
5. Have the system scanned for codes: A professional mechanic can use a scan tool to check for any diagnostic trouble codes (DTCs) stored in the vehicle's computer. This can help pinpoint the problem.
If you're not comfortable working on your car's electrical system, it's best to take it to a qualified mechanic for diagnosis and repair. Attempting electrical repairs without the proper knowledge can lead to further damage or injury.
