* Faulty Parking Light Switch: This is the most common cause. The switch, located on the steering column, might be stuck in the "on" position or internally shorted. This means it's sending power to the lights even when the switch is off.
* Short Circuit in the Wiring: A short circuit anywhere in the wiring harness leading to the parking lights can keep them energized. This could be due to damaged insulation, wires rubbing against metal, or corrosion. This is often difficult to pinpoint without a detailed electrical diagram and some troubleshooting.
* Faulty Multi-Function Switch: This switch often controls several functions including turn signals, wipers, and sometimes even the parking lights. A problem here could be causing the parking lights to stay on.
* Body Control Module (BCM) Issues: The BCM is a computer that controls many electrical functions in the car. A malfunctioning BCM could be incorrectly signaling the parking lights to remain on. This is less likely but possible.
* Aftermarket Accessories: If you've recently installed any aftermarket accessories, their wiring might be interfering with the parking light circuit, causing a short or incorrect signaling.
* Bad Ground Connection: A poor ground connection somewhere in the parking light circuit can cause unusual electrical behavior, including lights staying on.
Troubleshooting Steps (in order of easiest to hardest):
1. Check the Parking Light Switch: Try wiggling the switch gently to see if it affects the lights. This is a simple check and might point to the issue.
2. Check Bulbs: While unlikely to *cause* the lights to stay on, a bad bulb can sometimes cause the circuit to behave erratically. Replace any bulbs you find burned out.
3. Visual Inspection of Wiring: Carefully inspect the wiring harness for any obvious damage, frayed wires, or corrosion, particularly around the headlight and taillight assemblies.
4. Use a Multimeter: A multimeter can be used to check for voltage at various points in the circuit to isolate the short or faulty component. This requires some basic electrical knowledge or help from a mechanic.
5. Consult a Wiring Diagram: A wiring diagram specific to your 1996 Pontiac Grand Am is crucial for more advanced troubleshooting. You can often find these online or through a repair manual.
If you're not comfortable working with car electrics, it's best to take your car to a qualified mechanic for diagnosis and repair. Leaving the parking lights on will drain your battery.
