1. Check the Bulbs:
* Start with the easiest: This is the most common cause. Check all brake lights and turn signal bulbs (front and rear) to make sure they're not burnt out. Replace any that are. While you're at it, check the license plate light bulbs too, as they might share a circuit.
2. Inspect the Fuses:
* Locate the fuse box: Your Suburban likely has an under-hood fuse box and an interior fuse box (often under the dashboard). Consult your owner's manual to locate these and identify the fuses responsible for the brake lights and turn signals. They'll likely be labeled.
* Check for blown fuses: Carefully examine each fuse for a broken filament (a dark line across the metal strip). Replace any blown fuses with fuses of the same amperage. Do not replace a blown fuse with a higher amperage fuse; this is a fire hazard. If a replacement fuse blows immediately, you have a short circuit (see below).
3. Inspect the Wiring and Connections:
* Look for damage: Carefully inspect the wiring harnesses leading to the brake lights and turn signals, both at the bulb sockets and along their runs. Look for:
* Broken wires: Check for any exposed wires, frayed insulation, or broken connections.
* Corrosion: Look for corrosion on connectors, which can interrupt electrical flow.
* Loose connections: Ensure all connectors are securely plugged in. Sometimes a gentle wiggle is all it takes to make a bad connection work again.
* Trace the wiring: If you find damage, you may need to repair or replace the affected section of wiring. This can be challenging and may require some electrical knowledge.
4. Check the Brake Light Switch:
* Location: This switch is typically located near the brake pedal.
* Function: It tells the vehicle when the brake pedal is depressed.
* Testing: With the ignition on, press the brake pedal. Test for voltage at the switch terminals. If no voltage is present when the brake is pressed, the switch needs to be replaced.
5. Check the Turn Signal Switch (Multi-Function Switch):
* Location: This is typically located on the steering column.
* Function: Controls the turn signals, hazard lights, and sometimes windshield wipers. A faulty switch can affect both turn signals and brake lights if they share wiring paths.
* Testing: This is more complex and may require a multimeter to test for continuity and voltage across different switch positions. If testing reveals a problem, the switch usually needs to be replaced. It’s more involved to replace than the brake light switch.
6. Consider the Hazard Light Switch:
* This switch is also on the steering column. A problem here can affect brake lights and turn signals.
7. Check the Tail Light Assemblies:
* Sometimes the problem lies within the tail light assembly itself. A short circuit inside the unit could affect both brake and turn signals. It might be necessary to remove and inspect the assembly or replace the whole unit.
8. Consult a Mechanic:
If you're uncomfortable performing these checks or repairs yourself, or if you've checked everything and still can't find the problem, take your Suburban to a qualified mechanic. Electrical issues can be tricky, and a professional can diagnose and fix the problem efficiently.
Remember safety first! Disconnect the negative battery terminal before working on any electrical components. If you're not comfortable working with car electrical systems, it's best to consult a professional.
