94ZJ4ourfun

i have a 94 zj w/ a 4.0 and an auto, im having and abs problem. While running or driving,the abs light while come on and the volt gauge will drop,then theres a click from under the dash and then the light will go off and the gauge retuns to normal,ive checked all the abs sensors and most of the wires(that i can access).Tried searching but didnt come up with much help. Anyone have any other ideas on where to check or do i poss. need to replace the abs module? thanks