well, to be clear here ...
NONE of the 89-98 trac/kicks had ABS ...
BUT, many we're fitted with RWAL (Rear Weel Anti-Lock).
The RWAL system is sensenrd via a rear wheel speed ring in the diff AND a "load sensing" switch attatched to the diff.
If the speed ring sensor becomes a problem (broken, unhooked, etc) then the RWAL controller will throw a code.
IIRC, the "load sensor" can also cause a code.
The RWAL has it's own means for checking codes ... I'll look it up later this afternoon if you don't have a FSM.