abs comes on at slow speeds

[jimmerz]

I Have a 2001 silverado that the abs comes on at slow speeds. I took GMMerlin's advice, and took out the abs speed sensors out and cleaned the part where it contacts the hub. I put it back together and the abs still comes on. Can anyone Help me with this problem it is frustrating. Thanks Jimmerz

[HUNTERPAUL]

Need to use a scan tool to look at the abs data streme to see what is hapening and then you can start to diagnose the problem. Each abs speed sensor must give the same reading or the computer will think that a tire is sliding and will activate the abs unit.

[jimmerz]

Thanks for the advice. So I need to bring it to a dealer. There is nothing I can do to check this out myself. Thanks again. JImmerz

[tempfixit]

Originally Posted by jimmerz

Thanks for the advice. So I need to bring it to a dealer. There is nothing I can do to check this out myself. Thanks again. JImmerz

Read this thread it explains about testing sensors.
http://www.automotiveforums.com/vbul...ht=abs+sensors

Try doing a search by using abs sensors, there maybe more posts regarding this.

Hope this helps

[j cAT]

Originally Posted by jimmerz

Thanks for the advice. So I need to bring it to a dealer. There is nothing I can do to check this out myself. Thanks again. JImmerz

the abs front wheel sensors mounted on the front hubs produce an ac voltage of 500mv ac, this is with the hub rotating...

you must ensure that with you rotating the hub this voltage is suffecient.you should get slightly over the 500....if you get 400mv or less this is the amount that will cause your problem...I've done this before ...the rusted mounting surface must be cleaned to bright metal..it only takes a small layer of rust to mess this up...

if after cleaning and the voltage is still not correct then that side or that hub must be replaced...you then swap out the sensors and see which sensor is bad....if its not then you know which hub is bad on that side.

[jimmerz]

Thanks jcat that was good info. Thanks for all your help. So i can just pull one out. How will i know if it is that one. The abs light stays on if one is out. Then the abs wont activate at all.

[wafrederick]

Do it right the first time,replace the wheel bearing instead of cleaning or replacing the wheel speed sensor.GM should of done this instead of cleaning the wheel speed sensor.

[j cAT]

Originally Posted by jimmerz

Thanks jcat that was good info. Thanks for all your help. So i can just pull one out. How will i know if it is that one. The abs light stays on if one is out. Then the abs wont activate at all.

look to do this properly you MUST measure the voltage...it should be around 500MV AC....at the connector of the sensor...with you rotating by hand ...just cleaning and testing vehicle operation is not good...you swap the sensor and measure voltage,,find out what side is bad,,find out if sensor is bad, thats what the voltage reading while the hub is rotating will reveal..
as mentioned the hub may be bad, this voltage will reveal what hub

these sensors are very expensive ...the hubs aren't cheap either..only replace whats defective...most repair shops will just replace everything..

the cost of a meter is very cheap and also future use will save you time and money..