A spokesperson with the program's media relations department cited the ubiquitous "personal reasons" as the reason for Graham's resignation.
Bo Graham, the son of ASU head coach Todd Graham, did not immediately return a call seeking comment.
Todd Graham will not be available to media again until after the team's Tuesday morning practice.
Josh Martin an offensive graduate assistant who has worked primarily with the offensive line under Chris Thomsen in his one year at ASU, has been promoted to assistant coach. He is expected to coach running backs. Prior to becoming a graduate assistant at ASU in 2014, Martin was the offensive line coach at Tarleton State. He's also coached at Texas Tech as an offensive and defensive line assistant.
The Sun Devils also promoted Kenny Dillingham to offensive graduate assistant from a quality control intern. Dillingham was the offensive coordinator at Chaparral High School in Scottsdale prior to taking the position at ASU in 2014.
Bo Graham was not in attendance at Monday's ASU practice, but was with the team through the end of last week's practice schedule and spoke with SunDevilSource.com Friday about his running backs.
For the last two seasons, Bo Graham coached the program's running backs. Prior to that he spent one season as the team's on campus recruiting coordinator.