How to Test ABS Wheel Speed Sensors for Resistance and AC Voltage

Summary

In this video, the process of testing ABS sensors in a 2007 Saturn Vue is demonstrated, focusing on passive sensors. The host explains how to access and troubleshoot the sensors, including the use of a multimeter for both resistance and AC voltage tests. Key differences between active and passive sensors are outlined, and the importance of checking wiring for faults is emphasized. After confirming a faulty sensor through testing, the video concludes with guidance on replacing the wheel bearing assembly. The overall goal is to help viewers accurately diagnose and address ABS sensor issues in their vehicles.

Takeaways

• 😀 Check ABS sensors for resistance and AC voltage when diagnosing issues.
• 😀 ABS sensors can either be active or passive, with passive sensors being more common.
• 😀 A multimeter with both ohm and AC voltage settings is essential for testing ABS sensors.
• 😀 When testing a passive sensor, measure resistance and AC voltage output to assess functionality.
• 😀 Resistance values for ABS sensors typically range from 800 to 1700 ohms; check the service manual for specific values.
• 😀 Flaky wiring, moisture, or a dead sensor inside the wheel bearing assembly could be potential issues.
• 😀 Use an ABS sensor reader to help diagnose faulty sensors by identifying error codes specific to each sensor.
• 😀 Active sensors require voltage supply to generate an output signal, whereas passive sensors generate a signal by rotating the wheel hub.
• 😀 To check AC voltage, spin the wheel hub and measure the voltage generated by the sensor using a multimeter.
• 😀 If a sensor generates no AC voltage during testing, it is likely faulty and needs to be replaced.
• 😀 If no resistance is measured or values fluctuate wildly, the sensor is likely not working correctly.
• 😀 When diagnosing faulty sensors, ensure that the wiring is intact and that there are no issues with the connections before replacing components.

Q & A

What type of sensors are being tested in this video?

The video focuses on testing ABS sensors, specifically passive sensors for resistance and AC voltage.

Why is it easier to jack up the vehicle and remove the wheel when testing the ABS sensor?

It allows for easier access to the ABS sensor, especially for the rear wheels, making it more convenient to test and troubleshoot.

How are the ABS sensors connected to the vehicle’s braking system?

The ABS sensors are usually integrated into the wheel bearing assembly and connect to the brake controller at the front of the car.

What is the purpose of the ABS sensor?

The ABS sensor monitors the wheel's rotational speed and sends data to the onboard computer, helping control the anti-lock braking system.

What tool is essential for testing the ABS sensor?

A multimeter is essential for testing the ABS sensor. It should have an ohm setting for resistance and an AC voltage setting.

What could cause a malfunctioning ABS sensor besides the sensor itself?

A malfunctioning ABS sensor could also be caused by issues in the wiring, such as a broken or corroded connection.

What is the significance of checking the resistance value of the ABS sensor?

The resistance value helps determine whether the ABS sensor is functioning within the manufacturer's specified range. A reading that is too high or too low can indicate a faulty sensor.

What type of ABS sensors are there, and how do they differ?

There are two types of ABS sensors: active and passive. Active sensors require a supply voltage to generate a signal, while passive sensors generate a signal by measuring changes in resistance or AC voltage.

How can you differentiate between active and passive ABS sensors?

While both active and passive sensors can have two wires, active sensors typically have three wires, and they require voltage supply to function, whereas passive sensors do not.

What indicates that an ABS sensor is defective based on the AC voltage test?

If no AC voltage is detected while spinning the wheel hub, it indicates that the ABS sensor is likely defective.