1. Check the Fuses:
* Locate your fuse box: Your Blazer likely has an under-hood fuse box and an interior fuse box (often under the dash). Consult your owner's manual for the exact locations and fuse diagrams.
* Inspect fuses related to tail lights, brake lights, and turn signals: Look for blown fuses (broken filaments inside). Replace any blown fuses with fuses of the *same amperage*. Don't just put in a higher amperage fuse – that could cause further damage.
2. Check the Relays (If Applicable):
* Locate relays: Relays are often found in the under-hood fuse box. Your owner's manual should show a diagram indicating the location of relays for the turn signals and brake lights.
* Test relays (if you have a relay tester): A relay tester is the best way to check. If you don't have one, you could try swapping a known-good relay from a different circuit (if it's the same type) as a temporary test. Be extremely cautious when working with relays, some can carry high voltage.
3. Check the Wiring and Connections:
* Tail Light Assemblies: Inspect the wiring harnesses going to the tail lights for any damage (broken wires, corrosion, loose connections). Pay close attention to where the wires enter the vehicle body.
* Brake Light Switch: This switch is usually located near the brake pedal. It's a small switch that activates the brake lights when you press the pedal. You might be able to test it with a multimeter to confirm it's closing the circuit when the brake is pressed, or visually inspect for damage.
* Turn Signal Switch: Located on the steering column, this switch can fail and prevent the turn signals from working. This is less likely if *all* your tail lights are out.
* Ground Connections: Poor ground connections can prevent lights from working. Look for corrosion on the ground wires attached to the vehicle body.
4. Multi-Meter Testing (If You Have One):
A multimeter is the best tool to test for voltage and continuity in the wiring. You can test for:
* Voltage at the fuse: With the ignition on, check if voltage is present at both sides of the fuse. If no voltage at one side the problem is before the fuse, if no voltage at the other side the fuse is blown.
* Voltage at the tail light connectors: With the brake pedal pressed, check for voltage at the brake light connector. With the turn signal on, check for voltage at the appropriate connector.
* Continuity in the wires: A multimeter can check for breaks in the wiring.
5. Consider Professional Help:
If you're not comfortable working with automotive electrical systems, it's best to take your Blazer to a qualified mechanic. Diagnosing electrical problems can be tricky, and improper repairs can lead to further damage.
Remember safety first! Disconnect the battery negative terminal before working on any electrical components. Refer to your owner's manual for specific details about your Blazer's electrical system.
