Over the Holiday weekend, while cruising the lake, all of a sudden my 2002 outback ls lost all electrical and then died a few seconds later. We noticed that smell of electrical burn and smoke. After inspecting the engine compartment, we noticed that the big copper wire going from the solenoid to the starter had completely melted away. The whole starter seemed burned up. Also we noticed that the ignition wire going to the starter solenoid had touched the exhaust manifold and melted possibly causing it to ground out. Being a Holiday weekend I wanted to get back on the water ASAP, so I found a replacement starter/solenoid combo at a local auto part chain store that had a matching bolt pattern. It fit on perfect and look identical to the one I had before, except for the solenoid, it only had 3 leads on it as opposed to 4 that i had before. So we replaced the melted wires and and hooked up the 12v+ to one lead, the ignition to the other and the third had a wire going to the starter from the factory. So that just leaves the 4th mystery wire. We tested the new started with the 4th mystery wire disconnected and taped up. The boat started and ran fine for the rest of the weekend. Out of curiosity, we put a multi meter on the 4th mystery wire and it showed nothing when the boat was off or cranking, but showed 12v+ when it was running. Does anyone have any info on what it does and can i just get a new 4 lead solenoid and put it on this new starter. Thanks.