I'm hooking up a sub and amp to a factory head unit and have everything figured out except the remote turn on from the amp to the CD player. If anybody could give me a little guidance, I'd be very grateful. What happens when the remote is not hooked up?

If the remote is not hooked up, the amp will not turn on. There are a few new amps on the market now that do not require a remote turn on lead, but if your amp has an input for one, then it needs it.

So where would I hook that up on the factory head unit?

That I am not exactly sure... But you could just use whichever wire is the wire that gets power when the ignition is on, which I would also assume turns on the radio. Find the wire that turns on the radio, and splice into that one.

thanks, that's what I was thinking of doing. I appreciate it.

Some head units will actually have a lead for an amp turn on. My Pioneer 7200 has one. But others you can the power antenna lead.

This is true, but with the stock HU you are better off just using the power lead. I know that my HU retracts a power antenna (I don't have one) when you switch from the radio to the CD player, so that would shut off the amp if you used the antenna lead, right? I am just guessing.

I guess I didn't see that it was the factory HU. So yeah, any hot lead will work.

I used the switched +12V supply for my factory HU. I tied in to it behind the HU and ran the wires through my center console. I installed a switch inside my console in between the HU and amplifier though so I could turn the subwoofer amplifier on and off. That way I can turn off the subwoofer amplifier without having to turn the key off. Without a switch my amplifier would be on everytime the key was on, regardless of whether or not the radio was on.