Great addition when wanting to connect to the back of your truck or trailer. When using the 7 pin round connector with Ruff Tough Kennel fans there must be auxiliary power supplied to the vehicle socket on the back of your vehicle. Not all vehicles come with live 12 volt power supplied to the connector. You can test this with a volt ohm meter or a test light by going from the auxiliary to the ground terminals. On some vehicles the key must be turned on to supply power. If there is no power supplied to the plug, check your owners manual or contact your dealer.