I assume the Armada red wire is connected to the black wire on the brake controller.
This is likely the problem. If the vehicle is used it may be gone. If it is new you may want to look. As suggested above there may be a tow package kit (relay, fuses, etc) that has not been installed. This (Ford version) is a bag of parts either under the passenger seat or in the glove box. It is part of the tow package.
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This may be what you are saying about No power to the red wire. A quick check would be to see if there is constant power on any of the wires coming out of the Nissan connector. That would be the one the to connect to the black wire on the controller.
According to this page I would suggest checking the voltage at the black wire going into the controller.
Without totally tearing your connections apart see if you have 12 VDC at the black wire connection.
If you dont have 12 VDC you need to trace that wire back to its source. You indicated that if you hook this to a battery directly it worked as expected.
http://hensleymfg.com/wp-content/uploads/2011/02/tru-control-manual.pdf
