* Brake Light Switch: This is the most common culprit. The switch is located near the brake pedal and activates when you press the pedal. It's a relatively inexpensive and easy part to replace. If the switch is faulty, it won't complete the circuit to send power to the brake lights.
* Wiring: There could be a break, short, or corrosion in the wiring between the brake light switch, the fuse box, and the brake lights themselves. Check the wiring harness for any damage, especially near the brake pedal and the taillights. Look closely at connectors for corrosion or loose connections.
* Brake Pedal Position Sensor (if equipped): Some vehicles use a sensor to determine brake pedal position. A faulty sensor might prevent the brake lights from activating. This is less likely but possible.
* Body Control Module (BCM): The BCM is a computer that controls various vehicle functions, including lighting. A faulty BCM could be preventing the brake lights from working, although this is less common. Diagnosing this requires specialized tools.
* Ground: A poor ground connection can also prevent the lights from working. Check the ground points for corrosion or loose connections. The ground for the taillights is usually on the vehicle body near the taillights themselves.
* Wiring harness connector: The connector between the wiring harness and the taillights might be damaged or corroded.
Troubleshooting Steps:
1. Test the Brake Light Switch: With the ignition on, use a test light or multimeter to check for power at the switch terminals when the brake pedal is pressed. You'll need a wiring diagram for your specific vehicle to determine which terminals to test.
2. Visually inspect wiring: Carefully examine the wiring harness from the brake light switch to the taillights for any damage, breaks, or corrosion.
3. Check for power at the taillight sockets: With the brake pedal pressed, use a test light to check for power at the brake light sockets in both taillights. If there's power, the problem is likely within the light fixture. If there's no power, the issue is further up the circuit.
4. Check the grounds: Clean any ground connections you find.
5. Consult a wiring diagram: A wiring diagram specific to your 1996 Chevrolet Suburban is crucial for tracing the circuit and identifying potential problems. These are often available online or through repair manuals.
If you're not comfortable working with car electrical systems, it's best to take your Suburban to a qualified mechanic. They have the tools and experience to diagnose and repair the problem efficiently.
