* Brake Light Switch: This is the most likely culprit. The switch is located near the brake pedal and tells the car when to illuminate the brake lights. If it's stuck in the "on" position, the lights will stay on, even when your foot is off the brake. This switch can wear out, get stuck due to debris, or simply fail.
* Faulty Brake Pedal Position Sensor (if equipped): Some vehicles have this sensor to control various functions, including brake lights. A malfunctioning sensor might constantly signal that the brakes are engaged.
* Short Circuit in the Wiring: A short in the wiring harness running to the brake lights can create a constant ground, keeping the lights on. This might be due to damaged insulation, a pinched wire, or corrosion.
* Faulty Brake Light Bulbs: While less likely to *keep* the lights on, a faulty bulb could cause a short circuit. Replacing them might temporarily fix the problem before something else gives out.
* Central Tail Light Wiring or Fuse: If the problem is affecting multiple lights, the fault might lie in the main wiring harness or fuse box.
Troubleshooting Steps:
1. Check the brake light bulbs: Make sure they're not shorted out and/or burnt.
2. Inspect the Brake Light Switch: Locate the switch (usually near the brake pedal). Try gently wiggling the switch and see if the lights go off. If they do, it's likely the switch needs replacing.
3. Check the fuses: Inspect the fuse box for a blown fuse related to the brake lights.
4. Visual Inspection of Wiring: Carefully examine the wiring harness leading to the brake lights for any visible damage, such as frayed wires, corrosion, or burns.
5. Test the Brake Light Switch (advanced): You can use a multimeter to test the continuity of the brake light switch to confirm it's functioning correctly. (This requires some electrical knowledge).
If you're not comfortable performing these checks, it's best to take your Grand Prix to a qualified mechanic. Leaving the brake lights on will drain your battery and could potentially cause other electrical problems.
