* Low Brake Fluid: This is the most frequent cause. Low fluid triggers the warning lights because it indicates a potential brake system leak. Check the brake fluid reservoir and add fluid if necessary. However, if you have to add a significant amount of fluid, you have a leak somewhere in the system and need immediate professional attention. Driving with a leak is dangerous.
* Faulty Brake Light Switch: This switch signals the brake lights and often the ABS system. A malfunctioning switch can keep the lights on even with sufficient brake fluid. It's a relatively inexpensive and easy part to replace.
* ABS Module Failure: The Anti-lock Braking System (ABS) module is the "brain" of the system. Internal failures within the module can cause the warning lights to remain on. This is a more complex repair, often requiring professional diagnosis and potentially a replacement module.
* ABS Sensor Issues: The ABS sensors monitor wheel speed. A faulty sensor (usually located near the wheel hub) can prevent the ABS system from functioning correctly and trigger the warning lights. These sensors can be damaged by rust, debris, or impact.
* Wiring Problems: Damaged, corroded, or loose wiring in the brake or ABS system can cause intermittent or constant illumination of the warning lights. This can be challenging to diagnose without a multimeter to check for continuity and proper voltage.
* Brake Pressure Switch Failure (within the master cylinder): This switch monitors brake pressure and can trigger the warning lights if it fails.
Troubleshooting Steps:
1. Check the brake fluid level immediately. This is the first and most important step. If low, find the leak!
2. Inspect the brake lights. Are they working correctly? If not, suspect the brake light switch.
3. Have the ABS system professionally diagnosed. This usually involves using a scan tool to read codes stored in the ABS module's computer. This will pinpoint the specific problem more accurately than visual inspection alone. A mechanic with experience working on older vehicles is beneficial.
Important Note: Driving with a malfunctioning brake system is extremely dangerous. If you're unsure of the cause, have your vehicle inspected by a qualified mechanic as soon as possible. Don't attempt extensive repairs yourself unless you have experience working on braking systems.
