* Turn Signal Switch: A failing turn signal switch can cause intermittent problems. Worn contacts inside the switch could make and break connection erratically. This is a possibility, but less likely given the intermittent nature -- a completely failing switch would usually be consistently bad.
* Turn Signal Relay: A faulty relay could also cause intermittent issues. A relay that's overheating or has a failing internal contact might work sometimes and fail at others.
* Wiring Harness: This is a very common cause of intermittent electrical problems. Corrosion, broken wires, or poor connections within the harness (especially near the steering column or under the dash) are much more likely to cause intermittent turn signal failure. Movement of the harness might cause intermittent contact.
* Bulbs: A bad bulb *can* sometimes cause the entire system to act erratically because it creates extra load or resistance. But usually, with a bulb failure, the turn signals just don't work on *that* side entirely. If they're intermittently failing on both sides, the bulb is less likely the main cause.
* Hazard Switch: If your hazard lights work, it points away from a completely failed relay or a fuse issue. However, a problem in the wiring to the hazard switch circuit could still be involved.
Troubleshooting Steps:
1. Check the Bulbs: Start by visually inspecting all your turn signal bulbs (front and rear). A burnt-out bulb (or a loose one) can sometimes cause this type of intermittent problem.
2. Inspect Fuses: Check the fuse related to the turn signals in your fuse box (consult your owner's manual). A blown fuse is less likely to cause intermittent failures, but it's a quick check.
3. Test the Relay: If you can locate the turn signal relay (consult your owner's manual; it might be under the hood or in the fuse box), you can try swapping it with a known good relay of the same type (if you have one). This helps isolate if the relay itself is faulty.
4. Check the Turn Signal Switch: This is harder to test directly, but if you suspect it, a mechanic would have the tools and knowledge to verify its functionality. Often, it's replaced as an assembly due to its complexity.
5. Wiring Inspection (Professional Help): This is the most likely culprit. A mechanic with a wiring diagram and a multimeter will be able to systematically check the wiring harness for breaks, corrosion, or loose connections. This involves tracing the wires from the switch to the bulbs. It is the most time-consuming step and requires proper tools and knowledge.
Recommendation: Given the intermittent nature of the problem, the most efficient approach is to take your car to a qualified mechanic. They have the diagnostic tools and expertise to pinpoint the exact cause, whether it's a wiring issue, switch problem, or relay failure, much faster and more reliably than you would be able to DIY. Focusing on just the switch or relay might lead to unnecessary parts replacement.
