It is always wired with a relay, sometimes 2 relays for high and low speed operation.
You need power directly from the battery, with an inline fuse rated for the fans max amperage.
Wire gauge needs to be rated above this amperage or it becomes the fuse, and that is NOT a good thing.
Relay(s) also need to be rated above the Fan motors amperage.
A Relay is just a switch that can pass high amps but can be turned on and off with a low amp circuit.
This low amp circuit can be a switch on the dash or a thermostat on the rad/rad hose or engine.
Or you can have both, a switch and the thermostat controlling the E-fan.
A relay has 2 parts inside, the Load contacts and the Coil contacts
The Load contacts are the Amp rating for the relay, on automotive relays this is pin 30 and pin 87, when relay is "on" 30 and 87 are connected.
Second part is the Coil, this is just a coil of wire around a metal sleeve and core, when power passes thru this coil of wire it turns into a magnet, this pulls down the Load arm closing the Load connection.
Coil use pins 85 and 86, there is no + or - sides on this coil, if 85 has 12v and 86 is grounded Load connects, if 86 has 12v and 85 is grounded load connects
Wiring is pretty straight forward
Load
Battery------Fuse-------relay--------------E-fan motor------Ground(for fan motor)
Coil
12volt(switched or unswitched)------relay-------switch/thermostat----Ground
I personally like to use the Ground for the coil as the on/off, when running new wires a Ground wire can't "short" like a 12v wire can if it rubs or comes off.
But 12v side can be used as well.
If you want the fan to shut off with the key then use a switched 12v circuit, the relay's coil draws less than 1 amp, to you can tap into pretty much any circuit.
If you want the fan to continue running until rad/engine cools down(assuming thermostat control) then use an unswitched circuit.
Welcome Visitor! Please take a few seconds and 
