w202 abs light on

Hi all I have a 1999 w202 c250 , iv had it almost a year and the abs light has always been on how ever its cumming up for mot time so figure I really should sort it out
My question is , is there a way I can read the fault code with out taking it in to a garage have been looking at the obd code readers and merc adapter cables but these all seem to say they read engine codes and don't mention abs faults , I know with some older cars you can rig up a test light and count the flash codes

Basicly the abs light is perminantly on abs doesn't kick in , brake lights work , cruise control works

Any hints or tips for finding out what's causing it or ways to reset the fault would.be greatly appreciated cheers Andy