I recently installed a new Alpine In-dash CD to my wife's 88 740GLE.
Here's the wiring list as I found it.

Stereo Power (Hot all the time): Green
Stereo switched power: Blue
Memory/Preset power (hot all the time): thin Yellow
Power antenna turn on(switched by stereo): Red
Dash lights dimmer: Grey
Ground (earth): Black (SB)

(6-pin DIN cable to amp, black sheath)

All the speaker wires came from the amp, 4 of which
went back into the 9-pin (3X3 square) molex connector
that comes from the car wiring harness. 4 went to
a second 9-pin connector for just the rear speakers.

Amp power: Green
Amp ground: Black (SB)
Front speakers: Blue/Yellow + White
Front speakers: Blue/Grey + White/Grey
Rear speakers: Yellow + Black/Yellow
Rear speakers: Brown + Black/White

I connected the leads to the Alpine connector as follows:
(The Alpine has just one plug, with everything coming from it)
Alpine: Black Volvo: Black (Ground)
Alpine: Red Volvo: BLue (+12V switched)
Alpine: Yellow Volvo: Green (+12V constant)
Alpine: Blue Volvo: Red (pwr ant)
Alpine: White Volvo: Yellow (F spkr)
Alpine: White/Black Volvo: Black/Yellow (F spkr)
Alpine: Green Volvo: Brown (F spkr)
Alpine: Green/Black Volvo: Black/White (F spkr)
Alpine: White Volvo: White (R spkr)
Alpine: White/Black Volvo: Blue/Yellow (R spkr)
Alpine: Grey Volvo: White/Grey (R spkr)
Alpine: Grey/Black Volvo: BLue/Grey (R spkr)

Hope this helps anyone doing a similar installation.

--
Rob Bareiss, New London CT ::: "Roterande Fläkt Och Drivremmar!"