Found a new use for an old product. I have experienced some problems with the FM transmitter going across bridges with interference, etc when listening to audible books.
I had an old cassette cartidge that allows a device with a headphone jack and a cassette player to play through the stereo system - plug this into Nuvi's headphone jack and insert cartridge in the cassette deck and you are good to go. It doesn't work unless you are listening to something - that is not just traffic directions - does not have enough activity for the cassette to stay connected.
http://www.radioshack.com/family/index.jsp?categoryId=203232...
I have the same unit. Just
I have the same unit. Just play some Mp3's and it'll stay active. Instead of your adapter, I used a 3.5mm to RCA jack to connect to an audio in for my car. The same thing you would use to connect a dvd player to your car. Using this way does not require something to be playing