* Low Brake Fluid: This is the simplest and most crucial check. Low brake fluid points to a leak somewhere in the system, which is a serious safety hazard. Top it off (if safe to do so, use the correct DOT 3 brake fluid) and see if the lights go out. If they do, you still have a leak that needs immediate professional attention.
* Brake Light Switch: This switch tells the car when the brake pedal is pressed. A faulty switch can keep the brake light on all the time, and often the ABS light as well, due to the interconnectedness of the systems.
* ABS Wheel Speed Sensor: These sensors monitor the speed of each wheel. If one is faulty (damaged wire, bad sensor), the ABS system won't function correctly, triggering the warning lights. This is a common culprit.
* ABS Control Module (ABS Pump): The ABS module is the "brain" of the system. A malfunctioning module can cause the lights to stay on. This is typically a more expensive repair.
* Brake Pressure Sensor: This sensor monitors the pressure in the brake system and can trigger the warning lights if it's malfunctioning.
* Faulty ABS Hydraulic Control Unit: This part controls the distribution of brake fluid to the wheels within the ABS system.
* Wiring Issues: Damaged or corroded wires in the ABS system can cause intermittent or constant problems, leading to the illuminated lights.
* Master Cylinder: While less common, a failing master cylinder can cause issues that trigger both lights.
What to do:
1. Check the Brake Fluid: This is the absolute first step. Low fluid indicates a serious leak that needs immediate professional attention.
2. Have it Diagnosed: The best way to find out the exact cause is to have a mechanic or auto parts store scan your vehicle's OBD-II system. This will give you a diagnostic trouble code (DTC) that points to the specific problem.
3. Don't Ignore it: Driving with these lights on means your ABS system is not functioning. While your brakes might still work, you'll lose the anti-lock braking capability, potentially leading to loss of control in an emergency stop. This is a safety hazard.
It's important to get this issue addressed by a qualified mechanic as soon as possible. Attempting to fix these problems yourself without proper knowledge and tools can be dangerous.
