you will most likely have either a bendix or a wabco system. the wabco system needs a code reader the bendix has a series of lights on the module that are labeled (example right front sensor would have sen. R and f lit) sensors are located on the back side of the brake backing plate there will be a wire going to it checke for broken wires
they can be checked with a digital multi meter by unpluging and checking the resistance sometimes get pushed back from the tone wheel
simple to adjust tap the sensor in with a hammer but dont hit it too hard if it doesn't move it is probably stuck and may need replaced. when the coach is moved the sensor will move to the proper clearance
it may sound a little strange but bendix codes are cleared by running a magnet across the light panel the module is usualY under the coach above the rear axle nice to get at
wabco wheel sensor codes will clear when the module sees 5 to 10 MPH