I have very limited knowledge about auto wiring but this is what I found it very useful is that I get proper grounding whereever I test in the ciruit since it is grounded from battery all the time. It can used to powerup some accessories and test if they are working or not, I can check if I have short circuit. I was testing my headlight switch out of the truck powering this tool through cigrate lighter adapter. You can plug this tool into cigrate lighter adapter and power up and test any accessories.
I am working on getting my radio working, using my emergency jump starter which has cigrate lighter adapter, I am testing my radio functions in my home withou being in the truck. I dont think, I can do all that with MMMM.
It is just a convenience.
Ganesh
