Hi there,
I found an interesting side effect and, I'm not sure if this applies to the newer MP3 CD head units. As an experiment in this before I got my Mp3 head unit, I decided to test this article on a non-MP3 CD RDS Delphi head unit made in 2003 that I picked up from a junk yard for 10 bucks. From what I found out, the way that 9355093 chip allows the unit to turn on is basically like a serial relay. When the class 2 tells it to turn on the head unit, it basically turns the chip off and allows the 12volt memory/battery constant to power the head unit through 2 separate circuts. The ETR main power is the first, and the amplifier, power antenna, and accessory power are part of the second. If you simply disconnect just pin 8 on the chip, you turn off power to it and also disconnect the 12 volt memory from powering on the ETR portion of the head unit and allow the 12 volt ignition to power it on, however, 12 volt memory may remain still running to the amplifiers, power antenna out and accessory out. If you remove the chip completely, this defeats the 12 volt memory power from powering on that second circut and allows it to be controlled by 12 volt ignition as well. Once I recieve my MP3 CD head unit from 2006, I'll let you know my findings.
A note on the internal amplifiers: If power is still running to them without the main radio, this can cause them to heat up.
Thank you and I hoipe this helps most of you,
Starflare5.