The control of the ON and OFF lights is done by the PPS, so if it is not plugged in the lights will never work. The SDM tells the PPS which light to turn on and also how bright to make it. There are three light levels that I have decoded: very bright for headlighs off, middle bright for headlights on and instrument lights turned to bright, and dim for headlights on and instrument lights turned to dim. The actual brightness doesn't vary much, but the three commanded levels are there.
The passenger seat belt warning light is controlled by the BCM, so it can work, but apparently will not because the SDM must be telling the BCM that the seat is empty. Otherwise it would be on unless the seat belt was buckled.
If you want the ON light to be on, there are two pins in the connector that the PPS plugs into that you have to connect together. If you want it to be on, but dim, you can connect the pins with a resistor. If either of you are interested let me know and I will post the information here. Or, if you have the wiring diagram, you can probably figure it out for yourself. Just watch out, because connecting the wrong pins will blow the fuse.
Sky NA 2007 Midnight Blue
Sky RL 2008 Carbon Flash - Naked