The former Commonwealth champion, born in Perth to South African parents, made the accusation prior to the London Olympics in July after Steve Solomon earned selection ahead of Steffensen, who had beaten his teenage opponent in the trials.
The issue escalated after neither athlete had clocked the 'A' qualifying time which meant both relied on a nomination from the Australian authority, who opted for the younger athlete.
Solomon went on to finish eighth in the final in London.
AA said they had appointed an independent lawyer to investigate the accusations by Steffensen, who also claimed he had been 'discriminated against on many teams' but the governing body said no evidence was found to back up the complaints.
"The result of the investigation is that the allegations of racial vilification or discrimination made by Steffensen cannot be substantiated either generally or in relation to his non-selection in the individual men's 400m," AA said in a statement.
"The Board of Athletics Australia has determined that it will refer to an independent tribunal for determination a number of allegations against Steffensen.
"These include that his statements and conduct have been insulting or improper or likely to bring the sport of athletics into disrepute and that he has breached the Athletics Australia Team Member Code of Conduct."
AA chief Dallas O'Brien said in July they had selected Solomon at the time because he was 'our 19-year-old rising star' but Steffensen claimed the head of the organisation had lied to him about the reasons for the selection.
That claim was also dismissed by the AA, who said the tribunal would be convened in the new year.
Solomon led off and Steffensen anchored the Australia team in the 4x400m relay in London running similar 45.6 and 45.67 second splits as Australia missed out on a place in the final after ranking 10th in the heats.
The 30-year-old Steffensen won the 2006 Commonwealth Games 400m individual and relay gold in Melbourne but chose not to defend his titles in Delhi four years later after a series of disputes with AA.
He also won an Olympic silver medal in the relay at the 2004 Games in Athens.