So all day I've been attempting to install my MM3 on my 15 cummins but have yet to finish it. Everytime I attempt to program the ECM it keeps giving out error code 15210 "Write ECM request failed" which means it is not communicating. MM3 firmware is up to date, everything is connected snug, I have no clue what is going on with it. Seeing if anybody here could possibly guess what is going on.