My head unit has been driving me mad, I need to manually switch it off when I stop the car! Yes, LAZY. Well not anymore, I checked the wiring and found a switch wire on the plug.
There are two plugs at the rear of the head unit, one is black, this is the speaker connections. The other is white, this is the power connections. Its on the white plug. One end of the plug is a clip, this holds the plug in place on the head unit, at the other end, we have a red wire and a black wire, next down is a yellow wire below the black and a red/green below the red. Next row has a red wire, (this is the permanent live for the memory,) and on the other side is an orange wire. The orange wire is the switch wire!
I have cut the top red wire and the orange wire about 1 inch in from the plug, and soldered the orange wire from the loom to the 1 inch length of red from the plug. This makes the feed come on and off with the ignition switch.
But remember to tape the joint up with good quality electrical tape or self-amalgamating tape! And don't forget the loose red wire from the loom, this is permanently live, nor the orange stub coming out of the plug
My vehicle is a 156 2.0 TS Sportwagen and it DOES NOT have the CD player, nor the addtional amplifier that some vehicles have. So check first that the red feed is not needed to go to the amp first and then back to the front for control!
Hope this is useful.