ABS problem-wiring break?

[Myke456@aol.com]

Been trying to track down an elusive ABS problem on 87 5kcstq. Abs does not
function, yet all indicators show that it should. Car is now WMM (with my
mechanic), each removable component has been tried with working spares (new
sensor caps already installed). "ABS OFF" light continues to work the way it
is supposed to (yes, the bulb is good, yes it illuminates when ignition on
before startup, yes stays off when running, yes comes on when diff. locks
engaged) yet tires will skid on slick surface and there is no ABS feel in the
pedal.
He is now tracing wires. Not your everyday "check the sensors" problem.
Anyone have any suggestions?