9V to 40V? That can't be right, solenoids don't have voltage ranges that broad, perhaps the electronics unit works from 9-40 volts but solenoids are always given a single voltage because it's nothing more than a coil of wire, increasing the voltage from the 9v (with poor current sourcing 9volt batteries SUCK) to the 12V car battery that can source enough current to melt screwdrivers, no surprise it blew a fuse, if it hadn't it might have blown the coil. Can you take some decent pictures of the unit?