94 chevy s10 blazer problem

i have 94 chevy s10 blazer and the abs code is on so i used a jumper wire to get the code and the book i got doesnt have the code listed.So my question is there anyway to test the abs module

Confirm the indicated code and its non-existence. If the module indicates a non-existent problem then the module is likely the problem.

K is there anyway to check the system to see if it works
and also im tryn to figure out if its 4WAL or rear abs it got the system for the 4 wheel but it also has a speed sensor on the transmission