This is what listed under "Radio/Audio System Schematics" in Service Manual:
Figure 5: Cell 150 Power and Ground for Radio and Cellular Telephone (BoseŽ System)
Figure 6: Cell 150 Radio and Sound Processor Interface (BoseŽ System)
Figure 7: Cell 150 Compact Disk Changer and Sound Processor Interface (BoseŽ System)
Figure 8: Cell 150 Sound Processor Interface and Radio Speaker Amplifier (BoseŽ System)
Figure 9: Cell 150 Radio Speaker Amplifier and All Door Speakers (BoseŽ System)
Figure 10: Cell 150 Rear Deck Speakers (BoseŽ System)
If you can read those schemes, I can attach a pdf, but IMO you'll need multimeter anyway
