This is an edited version of something that's on my Google Plus stream. Hoping to find a couple of answers here among experts.

Backstory:
In the past, I'd cobbled together a single in-car dock for my iPhone 4 that could do all of the following from a single plug:
- Aux-out from the phone to my empeg through the dock connector.
- Charge the phone.
- Charge my Apple-brand Bluetooth headset that I lurve and that they don't make any more.

The last one was the tough one, because there's only one plug that'll do that trick: The one that comes with the headset. This is the plug I'm talking about:

Apple iPhone Bluetooth Travel Cable

That plug is special: No third party company that I know of makes one of those. You have to get it from Apple. The problem is that it doesn't do aux-audio out. You can get a billion different plugs and docks that will charge the phone and do aux-out, but not a single one that will also charge the Bluetooth headset.

So, wanting a super-clean installation in my car with as few protruding bits as possible, that's the plug that I'd modified to be an in-car docking connector. But like I said, the trick is that it doesn't do aux-audio-out. The necessary L/R aux-out pins (3 and 4) aren't even present on the connector. So what I had to do was dismantle the plug, and cannibalize the data pins to become the aux-out pins. In addition to grounding Pin 11 to force the audio to the aux-out... that pin-11-ground trick is what you did on old iPod cables to make the aux-out work.

That all worked! At least at first, before the iOS5 upgrade it worked. It's super-clever. Combined with a super low-profile phone mount on my dash (that I constructed from scratch with my housemate Fishy's help, better than any commercial mount I've seen), it made the iPhone a perfect combo GPS and Pandora-player box (God, I'm glad I'm grandfathered into AT&T unlimited data). It sits just behind my steering wheel and just below my line-of-sight to the windshield, including the headset charger all on the same plug. It was brilliant.

It all worked, and the worst thing that happened was that, each time I plugged it in, I got a warning dialog that I was using an old-school iPod charger that might reduce my cellular reception. I'm sure the dialog box was appearing because I'd cannibalized the data pins, so it couldn't tell it was a nice Apple-brand plug any more.

Then, the iOS5 upgrade hit.

And... what used to be a simple warning message now turns into... the phone won't charge at all in that dock. I think what happened is that the codepath that used to just put up a friendly warning has now changed. Now, instead of putting up a warning, it just refuses to charge if it thinks it's an old-school iPod dock.

So, following a tip on Twitter from a fellow Filker friend, I did the following:

- Cannibalized my second "backup" Apple iPhone Bluetooth Travel Cable, for the pins. (Pins from other less-expensive iPhone plugs were sadly the wrong shape and length to mate with the PCB in that special Bluetooth plug.)
- Using parts from both my Bluetooth cables, assembled a new plug that contained all the necessary bits: The Bluetooth headset charger, the aux-out pins, the grounded pin 11, the data pins, etc.

And boy was I surprised at the results. It charged the phone, it charged the bluetooth headset, and it put audio out on the aux... just not at the same time. As soon as I plugged the USB into some power, suddenly the aux switched back to the iPhone speaker. sigh.

Then I saw this: iPhone Accessory Message... the answer is 68k

And sure enough, all I needed to do was carefully lift pin 21, put a 68k resistor on it, and run that to ground. Now it does all of the things I want: iPhone charge, headset charge, aux-out, all at the same time.

At least it does them in my indoor tests with AC-adapter plugs. Install it into the car with my DC charger, and... and... and... The aux-out only works if I dock the phone before starting the car's ignition. Otherwise it uses the iPhone speaker. So now it's startup-order-dependent. Argh.

Well, at least I have the desired functionality, and a possible work around for when it's not working as desired. For instance, I could power the iPhone charger off the amp remote wire instead of the ignition-switched power. That would at least allow me to work around the startup order dependency if I forget to dock the iPhone before starting the car.

So my questions are:

- Anyone know how many amps an iPhone charger draws? And is that more than the Empeg's amp remote wire can handle? Can I just charge the phone straight off the Empeg's amp remote wire or do I need to do this through a relay?

- Anyone know how to get my iPhone aux-out to work without the startup-order dependency?