I just bought a Nissan USB+SD MP3 Adapter.It is cool,now share the installation,hope it is useful to you.
1: Pull out the unit from the car and touch the back of the unit for CDC port when the ignition is switched of.
2: Insert the CDC plug into the original car port correspondingly. Then insert the storage card.
3: Then check if the device works normally or not after power supply given from the car itself.
4: Put the wire harness into the proper and good place after the test successfully.