1. Visual Inspection:
* Bulbs: Start with the easiest check. Examine all three brake light bulbs (two on the taillights and one on the center high-mounted stop lamp (CHMSL) or third brake light). Look for burned-out filaments. Replace any faulty bulbs with the correct wattage. Make sure they're properly seated.
* Wiring: Carefully inspect the wiring harness leading to each brake light assembly. Look for any obvious damage, such as frayed wires, corrosion, or broken connections. Pay close attention to the connectors at the bulb sockets and where the harness enters the vehicle's body.
2. Testing the Bulbs (if they appear okay):
Even if a bulb looks fine, it could be faulty. Use a multimeter set to continuity (or a test light) to check if the bulb filament is intact. Disconnect the bulb from the socket and test the filament across the terminals. A good bulb will show continuity (a low resistance reading on the multimeter or a light illuminated with a test light).
3. Testing the Brake Light Switch:
This switch is typically located near the brake pedal. It's activated when you press the brake pedal.
* Visual Inspection: Check the switch for any damage or loose connections.
* Testing with a Multimeter: With the ignition ON, use your multimeter to check for continuity across the switch terminals. There should be no continuity when the brake pedal is released, and continuity when the brake pedal is pressed. If there's no change in continuity, the switch is likely faulty.
* Testing with a Test Light: You can also use a test light. Connect the test light ground to a known good ground point on the vehicle. Touch the test light probe to the switch terminal. With the brake pedal released, the light should be off. When you press the brake pedal, the light should illuminate.
4. Testing the Wiring and Connectors:
* Use a Test Light: With the ignition ON and brake pedal pressed, use your test light. Probe each wire at the connector going to the brake light assembly. The test light should illuminate at each wire if the circuit is complete. If the light doesn't illuminate at a particular wire, there's a break in that part of the circuit.
* Follow the Wiring Harness: Trace the wiring harness back from the light to the brake light switch and fuse box. Look for any breaks, corrosion, or loose connections along the way.
5. Checking Fuses:
The brake light circuit is usually protected by a fuse. Consult your owner's manual to locate the fuse box and identify the correct fuse for the brake lights. Use a fuse tester or visually inspect the fuse for a blown element. Replace any blown fuses with the correct amperage. If the fuse blows immediately after replacement, there's a short circuit somewhere in the system that needs to be identified.
6. Checking the Brake Light Circuit Breaker (if equipped):
Some vehicles use a circuit breaker instead of a fuse. This needs to be checked similarly.
7. Trailer Wiring (if applicable):
If you've recently used a trailer hitch, a problem there could cause the brake lights to malfunction. Check all connections at the trailer hitch wiring connector and ensure proper contact.
Important Notes:
* Safety First: Always disconnect the negative battery terminal before working with electrical components.
* Owner's Manual: Consult your 1996 Chevy Tahoe owner's manual for specific fuse locations and wiring diagrams. This will make troubleshooting much easier.
* Professional Help: If you're not comfortable working with automotive electrical systems, it's best to take your Tahoe to a qualified mechanic. A misdiagnosis or improperly repaired brake light system can be dangerous.
By systematically checking these points, you should be able to pinpoint the cause of your malfunctioning brake lights. Remember to replace any faulty components with the correct parts.
