It's the nav interface module. Trouble is they aren't getting power to the unit. Also, given the description below, I don't get why they say the Zumo XM output needs to plug into the aux port on the front of the radio. Thanks.
Road Tech™ Navigation Interface Module
Available exclusively for Harley-Davidson® Road Tech™ zumo Navigation Systems. The Navigation Interface Module will provide an integrated link between the fairing-mounted Advanced Audio Radio and a Road Tech™ zumo 660 or 665 GPS Navigator. When linked, the music volume will automatically drop when a GPS spoken command is detected, allowing you to hear the command through the radio speakers or the 7-pin communications-style headset. The module attaches directly to the radio, is concealed within the fairing, and does not require connection to the "AUX" input on the radio faceplate, allowing you to listen to a portable music device through your auxiliary input. Kit includes adaptor cable that permits stereo sound from the Zumo's internal MP3 player or XM® Radio.
76000024
IN-STORE PURCHASE ONLY Contact dealer for pricing and availability.