1. Bulbs:
* Check the bulbs: This is the simplest fix. The tail light filaments are different from the brake light filaments within the same bulb. The brake light filament may be working while the tail light filament is burned out. Replace any bulbs that are visibly damaged or don't illuminate when tested with a known good bulb. Make sure you're replacing them with the correct wattage bulbs.
2. Fuses:
* Locate the fuse box: Your Lumina will have a fuse box (likely under the hood and/or inside the passenger compartment). Consult your owner's manual to find the exact locations and diagrams. Look for fuses related to the tail lights (often labeled "tail," "parking," "rear lamps," etc.).
* Test the fuses: Visually inspect the fuses for blown elements (a broken wire inside). Use a test light or multimeter to confirm whether the fuses are good. Replace any blown fuses with the correct amperage rating. *Important:* If a fuse blows immediately after replacement, you have a short circuit somewhere in the wiring – do not continue until you've found and fixed the short.
3. Wiring and Connections:
* Inspect the wiring harnesses: Check the wiring harnesses leading to the taillights for any damage, corrosion, or loose connections at both the light fixtures and the connectors running to them. Look closely at the connectors; water intrusion can cause corrosion and poor connections. Pay close attention to areas that may rub against the body of the car.
* Clean and tighten connections: If you find corrosion, carefully clean the connectors with a wire brush and electrical contact cleaner. Make sure all connections are tight and secure.
* Trace the wires: If you're comfortable working with wiring, you can use a multimeter to trace the circuit from the fuse to the tail lights. This can help pinpoint a break in the wiring.
4. Ground:
* Check the ground connections: A poor ground connection can prevent the tail lights from working. The ground wire(s) should be securely attached to the car body. Clean any corrosion from the ground point and ensure a solid metal-to-metal connection.
5. Tail Light Switch:
* Less likely, but possible: In some vehicles, a separate switch controls the tail lights. While less common, a faulty switch could be responsible. This would require more detailed electrical testing to diagnose.
6. Multi-meter Testing:
A multimeter is essential for precise diagnosis:
* Test for voltage at the tail light sockets: With the lights turned on, use a multimeter to test for voltage at the sockets for the tail lights. If there's no voltage, the problem is before the socket. If there is voltage, the problem is with the socket, bulb, or the ground.
* Test for continuity: Use the multimeter to check for continuity in the wires leading to the tail lights. This will help locate any breaks in the wiring.
Important Safety Note: Always disconnect the negative terminal of your battery before working with any electrical components in your vehicle to prevent electrical shocks.
If you're not comfortable working on car electrical systems yourself, it's best to take your Lumina to a qualified mechanic for diagnosis and repair. They have the tools and expertise to efficiently find the problem.
