My d4 flashing on dashboard but the car is running fine what this mean. on 1993 Acura Legend

Just started this morning

Asked by for the 1993 Acura Legend
scan codes and post so we can adv
ok, checking my trans fluid and adding fluid to it will that help or hurt it?
Check fluid with engine off and on level ground.......'d' light flashing means there is a trouble code stored in the trans. control module. Need to have that scanned (generic OBDII reader will NOT work) with a scanner capable of communicating with acura powertrains.