* Short Circuit: This is the most likely cause. A short circuit in the wiring harness leading to the brake light can cause excessive current, quickly burning out bulbs. This short could be anywhere from the bulb socket to the fuse box, possibly even within the wiring of the taillight assembly itself. Corrosion, damaged wires (from rubbing against metal parts), or water intrusion are common culprits for shorts.
* Bad Ground: A poor ground connection means the electrical current can't easily return to the battery, causing excess current to flow through the brake light circuit and burning out the bulbs. Check the ground wire connection at the taillight assembly.
* Faulty Brake Light Switch: This switch is activated when you press the brake pedal. If it's malfunctioning, it could send an incorrect voltage or keep the circuit energized even when you're not braking, causing overheating and bulb failure.
* Incorrect Bulb Wattage: Using a bulb with a higher wattage than specified for your Malibu will draw too much current and burn out quickly. Always use the correct wattage bulb as specified in your owner's manual.
* Wiring Harness Problems: The wiring harness itself might be damaged or worn, especially around the bulb socket. Look for cracks, fraying, or signs of melting.
* Overheating Tail Light Assembly: In rare cases, the entire taillight assembly might overheat, leading to bulb failure. This is less likely but worth considering if other issues are ruled out.
Troubleshooting Steps:
1. Check the Fuse: Start by checking the fuse for the brake lights in your fuse box. A blown fuse is a relatively easy fix.
2. Inspect the Bulbs and Sockets: Visually inspect both brake light bulbs and sockets for any signs of damage, corrosion, or overheating. Clean the sockets with a contact cleaner if necessary.
3. Test the Bulbs: Before replacing bulbs, test them with a multimeter or in another working light fixture to ensure they're not faulty.
4. Inspect the Wiring: Carefully examine the wiring harness for any signs of damage, especially near the taillight assembly and the brake light switch. Look for chafing, corrosion, or broken wires.
5. Check the Brake Light Switch: Testing the brake light switch requires some electrical knowledge, but it might be a worthwhile step if other checks don't reveal a problem. This typically involves using a multimeter to check continuity.
6. Check the Ground Connection: Find the ground wire for the taillight assembly and ensure it's securely connected and clean. Apply dielectric grease to prevent future corrosion.
If you're not comfortable performing electrical work on your car, it's best to take it to a qualified mechanic. Ignoring the problem could lead to more significant issues or even a dangerous driving situation (if the brake lights fail completely).
