ABS light on Please Help!

I have a 2000 F-150 4x4 xlt reg. cab with the 4.6 and 4 wheel disk/abs brakes. I need some help trying to figur out whats causing the problem. I replaced the sensor on top of the pumpkin which kept the light off for about an 1/8th of a mile before the light came back on.the abs does not work at all and i've checked all the fuses. Any help would be appreciated.

I have a 2000 F-150 4x4 xlt reg. cab with the 4.6 and 4 wheel disk/abs brakes. I need some help trying to figur out whats causing the problem. I replaced the sensor on top of the pumpkin which kept the light off for about an 1/8th of a mile before the light came back on.the abs does not work at all and i've checked all the fuses. Any help would be appreciated.

I'd just like to thank everyone for their help here. In case anyone cares my problem is with the HCU unit which is about $700 bucks to have replaced.