Is the illumination connection related to the wiring for the cigarette lighter and ashtray somehow?
Here is why I ask.... I had this hooked up and all worked fine... one night I pulled the stereo and the button lights on the wheel stopped working... Great, I think, I must have messed with the wire on the stereo... Pull the console and I forgot to plug the lighter plug back in... Plug that in and it all works fine...
Works for a few weeks, plug in my cell phone one night and the lights on the steering wheel quit working... unplug it and shut the car off, still no workie... let the car sit for a few minutes, bingo, working again...
Seems odd to me, but also a little too much of a coincidence to not be related... does power on the ashtray/lighter light have any being on the illumination for the wheel as hooked up in this FAQ?