Please note, there are the following:
In order for a subsequently installed radio, including a JVC, to work properly you need to the two positive lead, ie red and yellow replace usually up to today. Otherwise, the radio does not save anything.
This adapter here, this step is already done! In other words, you should have crossed the cable in advance, you have to be turned off again. This circumstance is indeed pointed in the illustrated manual, but that can be overlooked, of course.
The following functions perform the buttons on the steering wheel from now:
Left Side Radio: tuning before, tuning back, station memory before
Left side CD, or USB: Track front, back track, folder before (at least in the MP3 mode)
Right side of everything: volume up, volume and source selection
The entries are, at least, before running radio in my case, with barely perceptible delay.
Conclusion: TOP! Very easy to install and function simply perfect!