new radio, cd head unit into mk4 vauxhall

I am struggling to understand the wiring requirements to put a new head unit into my son's Astra. The wiring harness connectors for the new unit seem the same as for the outgoing unit, however the new unit doesn't work when these are connected.

The wiring diagram for the unit (Alpine CDA-9854R) seems to suggest that it also needs a wire to the + on the battrey plus one to "an open terminal on the vehicle's fuse box or another unused power source which provides (+) 12v only when the ignition is turned on or in the accessory position".

Firstly, I am surprised that the existing loom connectors don't provide all that's needed  and secondly, if the stuff in " "s is needed, where do I find a suitable connection to use?

I really would be grateful if someone can help please?

Cheers.

Geepherder

thanks for the reply. I was being rather thick! I have now sussed the wiring for the head unit and it works. However, apart from the 4 standard speakers, my son has installed 2 additional  6 x 9's in the rear parcel shelf. We have used an old amp and connected a pair of  phono cables, a fused power cable plus the remote switch on lead. Unfortunately, only one new speaker will work (I've tries swapping the leads and established it's not the speakers that are faulty) and there's a lot of engine interference. The other strange thing is that it stops the other 4 'standard' speakers working as well.

If I take the fuse out of the power cable going to the amp, the 4 speakers come back on (with no interference). I have concluded the amp is faulty, so we need to replace that but could that also explain the interference and the 'knocking-out' of the other speakers??

Thanks to both of you. I think it's a safe bet the amp is shot, as the new speakers both work fine on the R/H connectors but nothing from the L/H. It's a very old amp we were given anyway.

The power and the phono's are running down the same side, is that a no no?