The easiest thing to do is to just grab a positive inside the Jeep somewhere, add an inline fuse (safety first!), run it through a simple on-off switch, and then connect it to the 4 inches of wire you left coming off the connector. This will give you full manual control of the fan, but that means that you’ll have to watch the temp gauge to make sure you don’t overheat the Jeep. That’s right, no relay. Sure, you could add one if you wanted, but the fan is small and doesn’t draw that much power, so even I, the relay king, don’t normally add a relay. I’ve used both switched and non-switched power in the past. You might want to use non-switched power if you want the fan to continue cooling even after the Jeep is shut off.