I have the lightning connector for my iphone 5. I have noticed that on the connector that the 4th pin is burned out. What data is transferred on the 4th pin? And should I be worried

How do you know it's 'burned out'? Maybe it's just discolored?

In either case, return the phone or cable to Apple for a possible warranty replacement.

As I've read, the pins are dynamic and can change function. I've not heard of your problem here on this forum. I'd suggest Googling for other's experience with your problem.

If it were me, I'd take it in to Apple and ask for a warranty repalcement.

Did you have a case on your phone? The pins on either side of the connector are soldered to the same connectors, so they are dynamically assigned, in order to make the connector reversible. One pin (don't know which one) detects the orientation and determines how to assign the pins. Some cases prevent the connector from fully inseting into the port and lets some pins connect but not others. This might have prevented the dynamic assignment from occuring properly and causing mis-connections to short. This only happens to one side at the time, so that's what might have happened to your cable.

I haven't seen any pinouts for the lightening cable, but as it is burned, I would assume it carries the current for charging the phone.

This happened to me a few weeks ago, and my cable stopped charging after a couple of days, so you should return it. Or maybe you could wait it out to see if it actually stops charging.

The same thing happened to me, I plugged my phone in and it wouldn't charge so I flipped it around and plugged it in and it started charging.. I got a good look at the pins and see 2 that are black/discolored - I have no clue how or when this happened. I am heading to the Apple Store for a replacement.

I noticed the same problem with my charger. Only the 4th pin on one side looks burned out. When I look inside the phone where the charger goes, I can see where the burned area is. It goes back and forth very rapidly from charging to not charging. If I flip it to the other side it works just fine.

At one point I also had an error message pop up saying that "Charging is not supported with this accessory"

I'll be going to the Apple store today. They are very good about replacing accessories.

I have the SAME exact issue. I have the 4th gen iPad, and after a while my 4th pin burned out on one side, then a while later the same on the other side. I even had the wrinkles on the lighting side. It's like 2 folds in the wire. When I plug it in it usuall charges but them every now and then quickly flickers between charging and not charging.. I went out and bought a new cable (not apple brand this time), and the same thing happened.. Now one side the 4th pin is burned.

I discovered this problem to my cable this morning 4th pin from the left burnt out on both sides, flickering from charging to not charging rapidly and saying accessory not supported, now this is my 2nd cable I have used it is a genuine apple replacement and I can guarantee that it has never been used for syncing has spent it's whole life plugged into the genuine apple charger that came with the iPhone 5

I'm having the same problem too. This will be my 3rd charger where the pins look burned out. I've had to replace 2 already since they just stopped charging (I own 3 for around the house). The one thing in common with all the chargers I owned is that they were exclusivley used with the Genuine Apple 12w USB power adapter. These cables were never used to plug into anything else other than an Iphone 5 and that power adapater.

Seems to me that the burned side has trouble making contact so it causes the phone to go in and out of the charge status when flipped burned side down. I've also gotten the "This accessory may not be supported" message.

Going to apple store tomorrow to get it exchanged AGAIN.

Just updating this as my wife was curious why there were markings on this particular pin as well. The link below shows the pinout and the pin with scarring seems to be Pin 5 where the power is transferred. It may be good practice if you keep your phone in your pocket with the lightning port un-protected to blow it out to avoid lint from scarring the contact on your cord and possible damage to your phone. I have a case that covers my lightning port and have never had this issue.

http://en.wikipedia.org/wiki/Lightning_(connector)