In the tutorial you can get description about active sensor, wheel speed sensor, and speed sensors. This tutorial contains information regarding wheel sensor, speed sensor, and speed.
There are lots of things such as sensors, wheel speed sensors, and resistance are explained inside the tutorial. These are selected from the tutorial:
ATE Troubleshooting Chart Wheel Speed Sensors Legend: ✔ =Yes = No A1 ✘ ABS/ESP fault indicator lights up ✔ A2 B2 Visual check: brake wear, brake fluid, wheel bearing play, sensor connecting wires, possibly sensor wheels, brake dynamometer readings okay? (internal resistance infinite) Renew sensor wheel/wheel bearing as directed by the manufacturer, continue with A8 B8 ✘ Repair wires/plug connections as directed by the manufacturer, continue with A9 ✔ A9 Erase fault memory, carry out test drive, read out fault memory ✔ E5 ✘ C6 Check actual values of wheel speed sensors for plausibility with diagnostic tester.
In addition, the tutorial contains info about sensor internal resistance, sensor, and passive sensor.