Here's a breakdown of troubleshooting steps:
1. Check the Bulbs (Again): Even though you suspect it's not the bulbs, rigorously check *both* taillight assemblies. Make sure all filaments in each bulb are intact. A seemingly good bulb might have a filament broken that's hard to see. Try swapping the bulbs from one side to the other to see if the problem moves. This helps isolate if the issue is the bulb or the wiring.
2. Inspect the Wiring and Connectors:
* Bulbs: Examine the sockets for corrosion, loose connections, or broken wires. Carefully pull the sockets out and inspect the terminals. Clean them with a wire brush or contact cleaner if needed.
* Harness: Trace the wiring harness from the taillights back towards the fuse box and body control module (BCM). Look for any signs of damage, chafing, or broken wires. Pay close attention to areas where the harness might be subject to movement or stress.
3. Check the Fuses: Check the fuse box (usually under the hood or in the dash) for any blown fuses related to the taillights or parking lights. Consult your owner's manual for the correct fuse locations.
4. Test the Parking Light Circuit: If you have a multimeter, you can test the voltage at the parking light socket to see if power is getting to it. With the parking lights turned on, check for voltage at the appropriate terminals. If there's no voltage, the problem lies before the socket, possibly in a fuse, relay, or wiring.
5. Body Control Module (BCM): The BCM controls many electrical functions, including lights. A faulty BCM could be causing the issue. This is a less likely but possible culprit, especially if other electrical anomalies are occurring. Diagnosing a BCM problem generally requires specialized diagnostic tools.
6. Grounding Issue: A poor ground connection can interrupt the electrical flow to the taillights. Check the ground wires associated with the taillight assemblies for corrosion or loose connections.
Important Considerations:
* Owner's Manual: Your owner's manual will have diagrams of the fuse box and wiring schematics that can help you pinpoint the problem.
* Professional Help: If you're not comfortable working with car electrical systems, it's best to take your vehicle to a qualified mechanic for diagnosis and repair. A faulty BCM can be expensive to replace.
By systematically checking these areas, you should be able to find the source of the problem. Remember to always disconnect the negative battery terminal before working with any car's electrical system.
