It pretty much powers everything except the starter motor. Although if it blows, the starter still won't work because the trigger circuit is powered by the FL1.25B. When the FL1.25B blows, the van will become completely dead except the charge light will illuminate. If it's damaged or partially melted, then some things may still work and/or everything may blink on/off intermittently. It's a good idea to check it annually to be sure it's in good shape and that the connection points are corrosion free. Putting a dab of dielectric grease on it's terminals will help prevent corrosion and prolong it's life. Tim