abs and rear diff. lights wont go off

hey guys, i have a little problem with my truck. i know the abs is supposed to disengage when you have it in 4lo and the locker engaged. well my rear differential and abs lights wont go off. the differential is not engaged and my abs does not work currently. this has happened a couple times before but the lights usually go away, however this time they are not. i do alot of lot of driving in the snow and use the 4wd quite often. any help would be phenominal. thanks