When wheel speed sensors (WSS) were first installed on cars and trucks, they were typically mounted on the CV joints or differentials. These sensors were not the most accurate and didn’t start working until the vehicle reached 5 to 7 mph. These are called passive wheel speed sensors.
As vehicles and ABS systems advanced, the wheel speed sensors moved to the knuckles and wheel bearings. These advanced sensors can detect small amounts of movement in the wheels when the vehicle is barely moving. They are called active sensors. But, with active sensors, the inspection and diagnostic process is more challenging. Why? Because the encoder ring is moved to the wheel bearing inboard seal, and the sensor is moved to the knuckle. The only way to diagnose the sensor and circuit is with a scan tool or scope.
Read the whole article from Brake & Front End, our sister publicaton, HERE.
