Abs system not working properly

[poker4me007]

I have a problem with the abs, maybe you guys can help me with... with all the fuses in and no light on dash comes on (no codes) go down the road, brakes work as they should, but just before I get to a complete stop the pedal will go to the floor and a groan noise from power booster...I can feel a vibration in the pedal when it does this...Doesn't do it all the time, about 3 out of ten times ...I've replaced the rear speed sensor that mounts on top the differential, I took off the two front speed sensors and cleaned them.. still does the same thing...Im running it now with the abs fuses out, and the brakes work as they should, the only problem is abs light is on now, and it'll probably lock up on ice... not too worried about the ice driving, since the 70's had lots of cars without abs, just that stupid light bugs me, plus I would want it to work as it should...Anyone have any Ideas...Thanks..

 

[XLTrunner]

There's the chance that one of the front hub bearing tone rings is corroded...causing an intermittent problem with the sensor reading correctly (hence, your 3 out of 10 times that the ABS is activated). Yes, I know it's inside the bearing and theoretically protected from contaminants...but, I know GM had a big problem (and, resultant recall 10-12 yrs ago on Chevy and GMC trucks) with theirs and, they were supposedly sealed inside. How old are the hub bearings?

 

[J_C]

You have the light on so it should have generated a fault code. Hook a scan tool up and see what is reported.

 

[XLTrunner]

I think he was saying the ABS light came on only because he pulled the fuse. Otherwise, no light. That's why I was thinking if the front sensors were functioning correctly with no dash light, maybe it was a problem with one sensor picking up irregular signals due to bad tone ring...same as what would happen if one wheel was turning faster than another. Only other thought would be maybe there's some issue with the ABS module.

 

[poker4me007]

Thanks guys,
The light only go's on when i take out the fuse...I'm leaning towards the front hubs also...I think i need to get a abs scan tool...If they weren't so expensive i'd replace the front hubs and be done with it..Moog hubs go for around $116.00 each (ouch) read on another forum to un plug the sensors spin the wheel and check resistance,Think i'll try that next.... I don't know how old the hubs are ,could be the originals, i've had the truck for about 4 years now....

 

[JDegenerate]

Following this. Mine does not throw a code either but the ABS comes on around 10mph whether I'm braking or not. Super annoying.

 

[Turdle]

well, for an abs problem with no obvious abs problem, I suspect the sensors. Time to check the front wheel bearings (2wd) -hubs for the 4wd trucks.

 

[96eb96]

Thanks guys,
The light only go's on when i take out the fuse...I'm leaning towards the front hubs also...I think i need to get a abs scan tool...If they weren't so expensive i'd replace the front hubs and be done with it..Moog hubs go for around $116.00 each (ouch) read on another forum to un plug the sensors spin the wheel and check resistance,Think i'll try that next.... I don't know how old the hubs are ,could be the originals, i've had the truck for about 4 years now....

Download forscan, it is free, works with cheap obd II adapter (BAFX, for example), and will definitely read the ABS sensors on a graph.

 

[poker4me007]

Hope this helps someone else...Ist one I replaced the front drivers side abs sensor and it works as it should now...replaced it with this one in the link... I bought two because there so cheap...I know there probably made cheap but for the price it was worth a try...
http://www.ebay.com/itm/New-OE-Qual...ash=item3d37a8a74b:g:fwAAAOSwpP9Y5uMf&vxp=mtr