Absolute Perfect

I am the proud owner of a JVC KD-R90BT and a Opel Zafira from of 2004.
It has never been so easy a vehicle-mounted steering wheel remote control to connect to a radio!
I had made my Vectra B at Kenwood remembered that I had there still consuming tinkering purely in the harness with a corresponding interface. The then spoke even the built-in Opel MID (radio display and on-board computer) with, but I can do without it.
It is really easy!
Radio out, cord, this adapter here just in between and you're done. My radio had no jack for the remote control, but a single Käbelchen. The more surprised I was that here was on the adapter even a matching connector for just the radio-sided cable here. Cable so a little stripping and firmly squeeze the cable lug side cutter carefully. DONE!

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!