Acura legend 1991

My buddy has an Acura Legend 1991 and his ABS light is on. I dont know anything about the ABS so could someone tell me what I should check on his car. Thank for the reply

My trusty integra/legend haynes manual says you should unplug the service check connector from the connector cover located under the glove box.
Bridge the 2 terminals of the connector with wire or a paper clip.
Turn the ignition to on, do not start the car. The ABS computer will display a trouble code by blnking the indicator light on the cludter. Read the code and tell me what it says.