Finally, I can install the head unit. At this point, I'm using an Alpine IVA-D105 multi-media unit.
Since I cannot install my own amplifiers, I have to use the factory JBL for now. I bought a Axxess TYTO-01 level shifter/harness to connect the two together. You can see it here along with the zillion wires from the head:
Luckily, this rats nest is only temporary. Once I can hook up the Alpine signal processor, the level shifter and all other analog lines will be eliminated.
The navigation unit needs a connection to the speed sensor. Again looking in the schematics, I find it conveniently is located in one of the harnesses that was connected to the JBL:
It is pin 4 of connecter K9. Looks like this:
Also required from the JBL harness is the connections for the steering wheel controls. The schematic shows it to be pins 6,7 and 8 on connecter K3 (brown, light green and grey):
The steering wheel interface unit says to install a 560 ohm resistor between pins 7 and 8:
All splices are, of course, protected with heat shrink:
I need both B+ and switched B+ for all the electronics. I fed a temporary run of #10 from the battery, through the firewall to the driver's side kick panel (temporary because I will be bringing a heavy line to the amplifiers later). Switched B+ is a bit more of a trick though. I discovered the cigarette lighter is a true ignition switch turning immediately on and off with the key. I don't smoke anymore and the plug is covered by the radio head anyway so I cut the switched line from it and fed it over to the coil of a 30A relay: