accessory power

I've been doing some aftermarket stereo additions to my 96 RMW, which involve using the original radio/head unit with an aftermarket wiring harness. After I got it hooked up, everything works fine except the accessory power doesn't work (first detent on key ignition). If I turn it to the second detent (start), it works fine.

I'm wondering is there a head unit harness wiring mistake that could account for this? All the original wires are (supposed to be) hooked up as original. It just doesn't make sense to me that it would be the wiring. There are only two power inputs to the head unit: hot-all-the-time and hot-in-run. There is no distinction from the radio's point of view between accessory and run, the hot-in-run wire supplies voltage either way.

Is there a fuse or relay that controls the accessory function?

Are there any other functions that work under accessory power but not when the car is off? I can't think of any, but that would tell me if it is just radio related or a problem with the accessory function on the car.

thanks for any ideas!

I believe the windows work on accessory power, as well as the HVAC fan.