Hopefully someone with more experience will chime in, but I'll try to attack it.The temp. switch(which if my memory serves me is on the passenger side between cylinders 6&8) sends a signal to the ECM(computer) which in turns energizes the relay. The wire for the fan "breaks and makes" through a contact on the relay. The relay energizes, the contact makes and the fan runs. I would disconnect the wire at the switch and see if the fan still runs(you know its not telling the computer to run it because its disconnected). If it still runs, I would look closely at the relay. Some people want the fans to run all the time(dont ask me why, if the cooling system is working properly its a waste of time and will shorten the life of the fan I would suspect). Make sure someone hasn't jumped the contact on the fan relay so the fan runs all the time. If you know your way around a volt meter you can always check to see if the relay is in fact getting voltage, if not the contact might be stuck or jumped out(jumper made across the terminals). you might also trace the fan wires and make sure they go to the relay and not some other source. Hope this helps
