1. ABS Sensor Issues:
* Faulty ABS Wheel Speed Sensor: This is the most common cause. These sensors detect wheel speed, and a faulty one prevents the ABS system from functioning correctly, triggering the light. A failing sensor might intermittently lose contact, leading to inconsistent braking and squealing. The squealing is likely unrelated *directly* to the sensor failure, but rather the result of other brake issues exacerbated by the ABS malfunction.
* Dirty or Damaged Sensor Ring: The sensor sits near a toothed ring (sensor ring) on the wheel hub. If this ring is dirty, rusty, or damaged, the sensor won't get an accurate reading. This can cause the ABS light to stay on and affect braking performance.
2. Brake System Problems (Independent of ABS, but often related because of the ABS light):
* Worn Brake Pads: Low brake pads are a very common cause of squealing brakes. The squealing is the result of a wear indicator rubbing against the rotor.
* Worn Rotors: Grooved or warped rotors can cause squealing and vibrations during braking, and poor rotor condition can further complicate ABS system operation.
* Brake Caliper Issues: A sticking or seized brake caliper can cause uneven brake pad wear, leading to squealing and potential ABS light illumination (because of uneven wheel speeds).
* Low Brake Fluid: Low brake fluid isn't a *direct* cause of ABS light, but it indicates a leak somewhere in the brake system, which *could* affect ABS functionality. Check the fluid level immediately.
3. ABS Module/Pump Problems:
* Internal ABS Module Failure: The ABS module itself could be malfunctioning. This is less common than sensor issues, but a possibility. This is a more expensive repair.
* Wiring Problems: Damaged or corroded wiring related to the ABS system can also trigger the light.
Troubleshooting Steps (Don't attempt major repairs yourself unless you have mechanical expertise):
1. Check Brake Fluid Level: This is the easiest and safest first step. Low fluid suggests a leak that needs immediate attention.
2. Inspect Brake Pads and Rotors: Visually check the thickness of your brake pads and the condition of your rotors. Look for excessive wear, grooves, or warping.
3. Have the ABS System Diagnosed: Take your car to a mechanic or auto parts store with OBD-II diagnostic capabilities. They can scan the system for specific trouble codes that will pinpoint the issue (e.g., a faulty sensor on a specific wheel). This is the most crucial step to identify the root cause.
Important Note: Driving with a faulty ABS system is risky. While you can still brake, the ABS won't prevent wheel lockup in emergency situations, potentially leading to loss of control. Get this issue addressed as soon as possible.
