* ABS Sensor Issues: The most likely culprit. During a brake job, the ABS sensors (located near the wheel hubs) can be easily bumped, damaged, or unplugged. Even a slight misalignment can throw off the sensor reading. Check for:
* Damaged wires: Look for any cuts, frays, or loose connections in the wiring harness leading to the sensors.
* Dirty or damaged sensor: Clean the sensors with a sensor-safe cleaner (brake cleaner is generally *not* recommended). Inspect for damage to the sensor tip.
* Improper sensor installation: Make sure the sensors are properly seated and aligned.
* Tone Ring Damage: The ABS sensor reads a "tone ring" on the wheel hub. If this ring is damaged (bent, broken, or rusty), the sensor won't read properly. This is less likely to happen during a simple brake pad or shoe replacement but *can* occur if the hub was removed or significantly impacted.
* Brake System Fluid Issues: While less common after a *simple* brake job, low fluid levels or air in the ABS hydraulic unit can trigger the light. Check the brake fluid level in the master cylinder reservoir. If it's low, you might have a leak somewhere. Air in the system requires bleeding, which needs to be done correctly, including bleeding the ABS unit (this often requires a scan tool).
* Wheel Speed Sensor Issues: This is similar to the ABS sensor issue above. Wheel speed sensors can malfunction, and their position near the brakes makes them vulnerable during the job.
* Electrical Problem: A loose or corroded connection in the ABS wiring harness could be causing the light. Check all connections for tightness and corrosion.
* Faulty ABS Module: This is less likely but possible. The ABS module itself could be malfunctioning. This typically requires professional diagnosis.
What to do:
1. Check the obvious: Start by visually inspecting the ABS sensors and their wiring harnesses. Look for any damage or loose connections. Clean the sensors carefully.
2. Recheck everything: If you're unsure about anything, double-check your work, ensuring you properly reinstalled all components.
3. Use a scan tool: A scan tool (either OBD-II reader or a professional-level scan tool) can read the ABS module's trouble codes. This will pinpoint the exact problem. Auto parts stores often offer free code reading.
4. Professional help: If you're uncomfortable troubleshooting the ABS system, take your vehicle to a qualified mechanic. The ABS system is complex, and improper repairs can lead to dangerous braking issues.
Don't drive your vehicle with the ABS light on. While your brakes will likely still function, the ABS may not, which reduces braking performance in emergency situations.
