1. Bulbs: This is the first thing to check! Burnt-out bulbs in the taillights are the most frequent cause. Inspect all bulbs (brake lights, turn signals, and running lights) in both taillights. While you're at it, check the front turn signal bulbs as well. They often fail in conjunction with the rear ones.
2. Fuses: Check the fuse box (usually under the hood or inside the car, often near the steering wheel) for blown fuses related to the taillights and turn signals. Your owner's manual will show you a fuse diagram indicating which fuses control what circuits. Look for fuses labeled "tail," "stop," "turn," or similar.
3. Flasher Relay: The flasher relay is a small electrical component that controls the blinking of the turn signals. A faulty flasher relay can cause the turn signals to not work at all or to blink rapidly. This is often located in the fuse box. You might be able to visually inspect it for damage, but replacing it is often the simplest solution if you suspect it's the problem.
4. Multi-Function Switch (Turn Signal Switch): This is the stalk on your steering column that controls your turn signals, wipers, and sometimes cruise control. A malfunctioning multi-function switch is a common cause of turn signal problems. These can be tricky and sometimes expensive to replace.
5. Wiring Issues: Damaged, corroded, or loose wiring in the taillight circuits, or anywhere along the path from the switch to the lights, can interrupt the electrical flow. This often requires tracing the wiring harness, which can be challenging. Check the connections at the taillights themselves for corrosion or loose connections.
6. Brake Light Switch: This switch is located near the brake pedal and activates the brake lights when you press the pedal. A faulty switch can prevent the brake lights from working, but usually wouldn't affect the turn signals unless there's a shared wiring issue.
7. BCM (Body Control Module): In some cases, a faulty Body Control Module can cause electrical issues affecting multiple systems, including lighting. This is less likely than the other issues, but possible. Diagnosing a BCM problem is typically best left to a qualified mechanic.
Troubleshooting Steps:
1. Visual Inspection: Start with a thorough visual inspection of all bulbs and wiring connections.
2. Fuse Check: Check the fuses that relate to your taillights and turn signals.
3. Test Bulbs: If possible, test the bulbs with a multimeter or by swapping them with working bulbs from another part of the car (like the headlights).
4. Check the Flasher Relay: Replace the flasher relay if it seems suspect.
5. Professional Help: If you're not comfortable working with car electronics, take it to a mechanic or auto electrician. They have the tools and expertise to diagnose the problem accurately.
Remember to always disconnect the negative battery terminal before working on any electrical components in your car to prevent accidental short circuits.
