The Harley breakout box is meant to be used in conjunction with a scan tool and a flow chart from your electrical manual.
It interfaces with your main harness and ECM to allow a technician to pinpoint individual circuits within your motorcycle. The Harley breakout box allows for voltage, ohms, and continuity testing of specific isolated circuits.
If you are having trouble diagnosing your motorcycle, it may be money well spent to have a dealership technician troubleshoot for you. The hour or two of labor buys you a tech with the most current information and (costly)tools needed to make a pinpoint diagnosis.
After the motorcycle is diagnosed; get the m/c home. Break out your service manual and the proper Fix My Hog videos to complete the repair yourself. It is important to know the limitations of your mechanical ability/knowledge or when you are limited by your tools.
Don’t just guess at what parts your motorcycle may need. As Bob says: “Don’t become a parts swapper”. Purchasing the wrong part is not only a waste of money but it also adds more downtime on your motorcycle.