Fan fire
 

Hi, yesterday smoke poured from Olive , our 440, and the radiator fan and associated cables to and from the switch were burning.
Luckily my wife had just arrived home and i disconnected the battery and poured water on the fan.

I've renewed cables and reconnected the switch, albeit with a heat damaged plug and the fan is permanently running.

Is the switch defective? or something more sinister going on? Why are there 3 cables to the fan, and to the switch?

Ideas Folks?