Both the GPS and the radio should come with appropriate plugs. The radio mfr's
plug will go into their unit and the Garmin plug will go into theirs. The
other end of the respective plugs should be a "pigtail" so you can tie together
inmput and output. That is, the output of the GPS ties to the input of the
radio.

That, at least, is how my Standard Horizon and (old) Garmin link.
Joel Albert
Potomac, MD
))