CD changer wiring (FM type)

["Rob Winchell" <rbw@avs.com>]

All -

I recently bought a CD changer from a fellow lister. Sony CDX-U303, FM
modulated type. I'm installing it myself, but am running blind as far as the
wiring goes.

The CD controller/modulator has 4 wires - red, yellow, black and blue/red.
It appears in it's previous installation the blue/red wire was not used at
all. Going from the Bentley diagram of the stock CD changer, the red and
yellow wires splice in with same wires going to radio, using 1A and 3A fuses
respectively. Black wire is ground. So, what's the blue/red wire for?

If anyone could help me out, or just give me a pointer to someplace else
this is discussed I'd appreciate it.

BTW, car is 91 200Q with Bose Gamma radio.

Thanks,
Rob Winchell
91 200Q
87 4kCS