I just bought a 2000 Explorer.  The ABS light would come on after a few
miles on the test drive.  The Ford dealer fixed it before I bought the
truck, but it took some time.  First they replaced the Break ECU (code
c1102) module.  This did not solve the problem.  They replaced it
again, still no fix.  They called Ford and were told to replace a G
sensor.  The problem is fixed.  I don't really know anything about this
stuff, but maybe this info can help.

Step 1: Turn off Caps Lock

Step 2: Make sure you have the correct amount of brake fluid in the
reservoir

Step 3:  Verify all your tires are the same size and type and properly
inflated. A slack tire can trigger the ABC light. The system compares wheel
revolution and a slack tire will show up as being off compared to the
others. The ABS interperts this as a faulty speed sensor. Same thing if all
your tires are not the same size and type.

Step 4: Check the rear wheel sensor (but you have already replaced this, so
I assume it is OK).

Step 5: Pressure wash the area inside the front hubs. You are doing this in
an effort to clean any trash out of the encoder wheels that might be
confusing the sensors. I don't think this is the problem, but it can't hurt
to try this.

Step 6: Visit your dealer and have them read the stored fault codes. At this
point you are at their mercey.

Ed