1. Check the Obvious:
* Brake Pedal: Make sure the brake pedal isn't sticking or the brake lights stay on even when the pedal is released. A sticking pedal often indicates a mechanical issue within the brake system (e.g., a seized caliper, low brake fluid). This is the most important step, as a failing brake system is dangerous.
* Brake Fluid Level: Check your brake fluid reservoir. Low fluid is a serious problem and suggests a leak somewhere in the braking system. This needs immediate attention.
* Bulbs: The most common cause. Check all three brake light bulbs (two on the rear and one on the center high-mounted stop lamp (CHMSL) if equipped). Replace any burned-out bulbs. Make sure the bulbs are properly seated.
* Fuses: Check the fuse box for blown fuses related to the brake lights. Your owner's manual will show you which fuses control the brake lights.
2. If Bulbs and Fuses are Okay:
* Brake Light Switch: Located near the brake pedal. This switch activates the brake lights when the pedal is pressed. It's a relatively inexpensive and easy part to replace if faulty (but do this only *after* checking for low brake fluid, since low fluid can trigger false brake light activation in some vehicles.)
* Wiring: Inspect the wiring harness leading to the brake lights for any damage, corrosion, or loose connections. Pay close attention to the areas where the wires might be prone to rubbing against metal parts.
* Tail Light Assemblies: Make sure there isn't a problem with the tail light assemblies themselves (broken wires inside the assembly, etc.).
* Brake Light Switch Adjustment: Sometimes the brake light switch needs adjustment. A properly working brake light switch should click when the brake pedal is pressed.
3. If You're Unsure:
* Test Light or Multimeter: Use a test light or multimeter to check for power at the brake light sockets with the brake pedal pressed. This will help pinpoint the location of the fault.
* Professional Mechanic: If you're not comfortable performing these checks or if the problem persists, take your S10 to a qualified mechanic for diagnosis and repair. This is especially important if you suspect a brake system leak.
Important Safety Note: Driving with malfunctioning brake lights is extremely dangerous. If you're unsure about any of these steps, don't drive the vehicle until the problem is fixed. Brake system failures are a serious safety risk.
