Rick's Free Auto Repair Advice

Test an ABS sensor

How to test a wheel speed sensor

If the ABS light is on and you suspect a bad sensor, here’s how you test an ABS sensor

ABS sensors are divided into two categories: active and passive. Passive sensors generate an AC voltage that you can test with a digital multimeter. An active sensor produces a digital square wave and you can only test those with a scope. This article describes how to test an ABS sensor of the passive type.

Disconnect the sensor at the wheel and use a digital multimeter to check the resistance of the sensor. ABS sensorCheck the manufacturer’s specs to see the acceptable range. If you do not have access to that data, then check another wheel sensor and compare the readings. They should be close to one another. Then, change your meter to read AC volts. Spin the wheel and you should see approximately 1 volt. Do the same at another wheel to compare the readings. Before you condemn the sensor, check the reluctor ring for missing or cracked teeth (also known as the tone ring). Also, check the sensor and remove any metal filings, dirt, or grease that may have accumulated on the sensor surface.

© 2012 Rick Muscoplat

Posted on by Rick Muscoplat

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