Wheel speed sensors - how to test?

[ebodell]

Hello,
New member here. I have a 1998 GMC Yukon with the 350. A few days ago my ABS light came on. It was somewhat intermittent (sp?) at first and would go on and off. Now it mostly on. I have noticed no difference in the braking performance. Today I pulled both front tires and checked the wheel bearings and they are fine. I would like to test the wheel speed sensors to see if the issue is there. I tried to measure the resistance across the sensor on both sides and measured 20M ohm with both the key on and off on both sensors (right and left). With this result I assume that I am not measuring correctly or measuring the correct performance criteria (as I only measured the resistance). Does anyone on here know how to test these sensors? Other than the light on the dash it is not showing any other symptoms.

The truck has 165K miles so I understand that I have to deal with issues that most people never see.

Hopefully this post is in the correct catagory. I did a search first and could not come up with any performance criteria for the wheel speed sensors.

 

[kcb37]

Advance/Auto zone/Oriley should all be able to read the code and tell you which sensor.
Just make sure you tell them you need an abs code read.

Is it 2 or 4wd?

 

[SunlitComet]

Multi meter leads on both wires of the sensor. set to ac mv scale and hand spin the wheel. Should see at least 350VACmv. If less sensor is dirty or dead.

 

[ebodell]

Multi meter leads on both wires of the sensor. set to ac mv scale and hand spin the wheel. Should see at least 350VACmv. If less sensor is dirty or dead.

Thank you! That is exactly what I was looking for.
Cheers,
Erik