there are a couple of "learn in" procedures that should be done when replacing and ECM, and one of them requires the cable and software, also worth being concerned about is the 'model year' break in the ECU. there is a different ECM for trucks with the pressure sensor on the top of the throttle body than trucks with the pressure sensor screwed into the side of the throttle body. you do confirm that the code shows up while the engine is running and not just when you first turn on the key (can not reads the hour meter at all).