The standard wiring harnesses don't work with the Street Glide. That is the challenge. Sadly the factory does not make the right harness and just says it is not supported.
Turns out that the Navigation Interface Module (often shortened to "NIM" in the postings) just needs a 6 wires.
If you look at this diagram
http://www.cvoharley.com/smf/index.php?topic=53364.msg940314#msg940314I did as this diagram suggests... I purchased the overlay harness and I cut the 275B connector that connects to the NIM off (leaving as much wire as I can) and connected the 6 wires to the existing harnesses.
Battery + & Ground were easy to find. The CAN+ / CAN- need to be sliced into the existing wires on the back of the radio. Then the Audio+/Audio- need pins into unused positions in the back of the radio (as per the instructions). Since I did not have the pins I just cut those wires off from the overlay harness and used them.
The other hint is that I had a Garmin Zumo 660... Not the Harley Davidson version which is nearly identical "Road Tech Zumo 660". It is painted differently, has HD dealer locations preloaded, but more importantly (and is critical for operation with the NIM) is a special signal that tells the NIM that audio is being spoken. This little detail had me very confused, I had the wiring correct, but the NIM was not working... All because I had the wrong model Zumo.
If you have questions I would be happy to help.