Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Normal Operation and Fault Conditions
Active wheel speed sensors generate a square wave signal proportional to wheel speed which is sent to the ABS module. Each wheel speed sensor is connected to the ABS module through 2 wires and a connector at each wheel speed sensor. One wire is for sensor voltage supply from the ABS module and the other wire is for the signal return to the ABS module. When the ignition mode is set to ON, the ABS module carries out a self-test by sending a reference voltage through the wheel speed sensors and their circuitry.
Vehicles equipped with active park assist use bi-directional wheel speed sensors. If the vehicle is equipped with active park assist, the Rotunda Active Wheel Speed Sensor tester cannot be used to diagnose the wheel speed sensors.
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.
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