Brake pad wear sensors are electronic components integrated with the brake pad assembly, typically located near the friction material. These sensors utilize a physical or electrical method to detect diminishing pad thickness during normal braking operation. Upon reaching a predetermined wear threshold, the sensor activates a warning indicator on the vehicle’s instrument panel. Common technologies include a shear-based pin breaking a circuit or a capacitive measurement of pad distance. Signal transmission is generally resistive, providing a voltage reading to the vehicle’s electronic control unit. Replacement is typically performed alongside brake pad service to ensure continued wear monitoring.