ABS/breake light on no diagnostic code???
 

Hello
I'm new here and I have a problem...
My 1994 ranger 4.0 XLT 4x2 ABS/break light on at all times and no diagnostic code except for 539 (is your A/C on). break fluid reservoir is full, I replaced the ABS sensor on the differential and disconnected the ground to the battery. What should I look at next? any input would be greatly appreciated. Thanks