You do not state which model, but the green LED on the various models functions the same. What you have is normal. Do you have the LCD remote panel? THAT panel will tell you if you have any fault. I am always curious when people post this type question. Why not go to Magnum Energy's website and read the operation manual for your particular Inverter and also download it and print for future use????? As I stated, the flashing is normal and when you paste the link provided will tell you what the various timing of the flashes mean. Go to section 3.7 in the manual. Doug
http://magnumenergy.com//wp-content/uploads/2012/08/64-0002-Rev-B-ME-Series_Web.pdf