I don't think I used an orange wire from the TR7 or the head unit. I DO remember there is a six pin molex connector on the back of the IXA-W404 that has I believe 2 wires coming out of it and I wired mine to that. IIRC the wire I used was the one marked REM. IN and I want to say it was white with a brown stripe or brown with a white stripe. Sorry, I hope I'm not confusing you more lol. It's been a while since I hooked it up and it's installed right now. I know this for sure, Black from the TR7 goes to Black on the vehicle adapter harness, Red on the TR7 goes to either Red or Yellow on the vehicle adapter harness (The way I understand is it doesn't matter which)
EDIT because it wouldn't let me finish typing.
Past that, I'd only be guessing. I just spliced the wires together exactly how the little orange (or yellow) card that came with it told me to. Did yours come with that card? I can't find mine right now, but mine was exact instructions on how to wire to an Alpine HU. Just wire it up according to that, and then hook up the power pack after that's all taken care of and you should be golden. If not, you may have a faulty TR7.