Aftermarket Fm Cd Changer

[Bosnjo]

Waiting to receive Avensis Sedan 1.8 VVT-i. In a meantime I was looking for CD Changer to install when car arrives. As all Avensis models have new Radio Head since beginning of 2004, there is no any kind of interface to plug aftermarket CD Changer. Toyota CD Changer is too expensive for features that offers. So, the only way out is to get one that works as FM transmitter. I found interesting one (there are no many in Portugal). It's Pioneer CDX-FM657 with CD Text, CD Text Custom File and many other good features. Final price is 405€. I guess I'll go for that one.

Untill car arrives I need to know what do I need to install it in trunk. I saw that it has wired remote to put in a dashboard. That one gives all commands and has display for CD Text, track, disc etc. So, that is one wire to pass from trunk to dashboard. I went to the dealer and saw in one Avensis that it has one little black round box with 12V wires in the trunk. Dealer wuldn't know what is it for.

My question is: Beside the cable of remote control, what else do I need to pass from dashboard to the trunk? Do I need ignition power (interuptable) or permanent one is enough? Is the one in the trunk free to use for CD Changer? Are there more wires to pass or it would be only the one of the remote control if the 12V in the trunk is OK tu use?

Thanks to all