1. Safety First!
* Disconnect the negative battery terminal before working on any electrical system. This prevents accidental shorts and shocks.
2. Visual Inspection:
* Bulbs: Start with the simplest check. Examine both brake light bulbs. Are they burnt out? Replace them with the correct wattage bulbs (check your owner's manual or a parts store). A 1967 El Camino likely uses standard bayonet-style bulbs. Make sure they're seated properly.
* Wiring: Look for any visible damage to the wiring harness leading to the taillights. Check for frayed wires, broken insulation, or corrosion. Pay close attention to the areas where the wires enter the body and taillight assemblies.
* Tail Light Assemblies: Inspect the taillight housings for cracks or damage that could interrupt the connection to the bulbs. Make sure the bulbs are making good contact with their sockets.
* Brake Light Switch: This switch is usually located on the brake pedal arm. Visually inspect it for damage or loose connections.
3. Testing:
* Test Bulbs (if not visibly burnt): If the bulbs look OK, test them using a multimeter or by swapping them with working bulbs from another light (like a turn signal, if you're confident in its working condition). This helps isolate whether the issue is the bulb itself or the wiring.
* Test the Brake Light Switch: With the ignition on, have someone press the brake pedal while you test the voltage at the brake light switch terminals with a multimeter. You should see voltage when the brake is pressed. If not, the switch might be faulty and need replacing. This often requires careful access under the dashboard.
* Test the Wiring: With a multimeter, you can test the voltage at the various points in the brake light circuit. This requires knowing the wiring diagram for your El Camino (available online from various sources, or through restoration clubs). Trace the wiring from the brake light switch to the taillights, checking for voltage at each connection. A lack of voltage indicates a break in the circuit somewhere between those points.
* Test the Ground: A poor ground connection is a common cause of electrical problems. Make sure the taillight housings are properly grounded to the car's body. Use a multimeter to check the ground connection.
4. Repair/Replacement:
* Replace Burnt-Out Bulbs: If the bulbs are faulty, replace them.
* Repair Damaged Wiring: If you find damaged wiring, repair it using proper automotive wire, connectors, and electrical tape. Solder connections for a more robust repair.
* Replace the Brake Light Switch: If the switch is faulty, replace it. This usually requires accessing it under the dashboard.
* Replace Taillights: If the housings are cracked or damaged affecting the connections, replacement might be necessary.
* Improve Ground Connections: Clean and tighten any corroded ground connections. You may need to add a new ground wire if the existing one is insufficient.
5. Resources:
* Online Forums: Search online forums dedicated to classic Chevrolet vehicles. You'll find many helpful tips and troubleshooting advice from experienced owners.
* Repair Manuals: A 1967 El Camino repair manual will be invaluable. It contains wiring diagrams and detailed information on the electrical system.
* Parts Stores: Auto parts stores can help identify the correct bulbs and other parts. They may also have wiring diagrams for your vehicle.
Troubleshooting electrical issues can be challenging. If you're uncomfortable working with car electrical systems, it's best to consult a qualified mechanic specializing in classic cars. They have the experience and tools to diagnose and fix the problem efficiently. Remember to reconnect the negative battery terminal once you have completed your repairs.
