Michigan State Brakes Certification Practice Exam

Which of the following is true when inspecting wheel speed sensors?

1. You should measure the air gap between the sensor and the reluctor wheel teeth

2. They should be checked for physical damage only

3. Visual inspection is sufficient without measurement

4. Sensor resistance should not be measured

The correct answer is: You should measure the air gap between the sensor and the reluctor wheel teeth

Measuring the air gap between the wheel speed sensor and the reluctor wheel teeth is essential because this gap can significantly affect the sensor's performance. An optimal air gap ensures that the sensor can accurately detect the magnetic field created by the rotating reluctor wheel, which is crucial for providing precise information to the vehicle’s anti-lock braking system (ABS) and traction control systems. If the air gap is too large or too small, it can lead to incorrect readings, causing potential issues in vehicle handling and safety. Visual inspection, while important, may not provide a complete assessment of the sensor's functionality. Checking for physical damage only would overlook critical aspects such as the condition of the air gap and the sensor’s electrical characteristics. Relying solely on visual inspection or neglecting to measure key parameters like resistance can lead to undetected issues that might compromise performance. Thus, emphasizing the importance of measuring the air gap directly aligns with best practices for ensuring the reliability and accuracy of wheel speed sensors during vehicle inspections.