This thread is nearly three years old jl. I'm sure the OP probably figured something out by now. From the description in the thread he likely just had a breaker or broken wire problem. He'd replaced the fan switch and the machine only overheated when the fan wasn't running unless wired up straight to 12v power.Not sure about your model, but make sure the water pump is primed and actually moving coolant. Fan won't come on if there is no coolant flowing across the sensor to read temps from. Had this problem on my 2004 500 ho. Once I got it primed the fan would come on and the engine no longer overheated.