abs breaks

Hello. I've been trying to help a friend with his 98 gmc. When stopping the breaks are normal until getting slow then the abs motor comes on and the break pedal sinks to the floor. The truck stops but the abs motor runs constant until you release the pedal. This is happening on dry roads. What is there to check before condemning the abs module?

Check both front hubs for play. Pull both the speed sensors out of the hubs and check for a rusty build up on them. If there is then that hub assy will need replaced. If not, there still is a problem with one or both front hub assy's. With the year and I'm assuming high mileage, probably best just to replaced both front hubs.

Very common problem, here's how to diagnose it: http://ww2.justanswer.com/uploads/GMGreatWrench/2010-09-14_004540_abs_bulletin.pdf

Sounds like you need new ABS sensors, which you can grab here (http://www.gmpartsonline.net/parts/1998/GMC/C1500/Sierra%20SL?siteid=215055&vehicleid=176125&section=ELECTRICAL&group=ELECTRICAL&subgroup=ABS%20COMPONENTS&component=ABS%20sensor).

Hello. I did replace the front wheel speed sensors. The lights didn't go out. I started to check wiring and grounds. When I pulled the power plug off the abs motor the ground was covered with green blue slime. I cleaned it all up and made sure there was good contact. plugged it in and started it up and the lights went out and have not come back on. Glad to have the lights off. Thanks for the help!