iPhone 4 will charge in wall, but won't sync or charge via USB

I have an iPhone 4 that is showing its age. It will charge when plugged into the wall charger. However, when I plug the same cable into a USB port on my computer it will not charge or be recognized at all by iTunes.

When I plug my new iPhone 4S into the same cable it is recognized and syncs just fine.

Is there anything I can try to get the iPhone 4 syncing via USB so I can update the OS and sync with iTunes, etc?

Edit: I will occasionally get the "This accessory is not optimized for this iPhone" message when I plug the iPhone into the cable connected to the USB port.

Solution 1:

I know, in most cases, this problem to be the usb port on the iphone. Unfortunately this part seems to be a part which only one in five of these parts to be good from experience. Either the mic or data port are defective which makes a diy repair frustrating. Most people will change it once they hit a defect part and give up. Don't give up. Trying to help people who are frustrated as I was. Usually occurs when you update with a port having bad contacts and ends up with a no sync or no voice on phone mic. May not be what you want to hear.

Solution 2:

I was having the same problem- tried everything (quick cleaning, new cables; both wall and computer cables, etc.). I was convinced it was a software problem and was super pissed at apple. Then I took a flashlight and looked at my phone's connector contacts (on the far right and left of the "row of information pins". I noticed, even after cleaning, there was still some lint or dirt. So I bought some Cyber Clean (Swiss formula)- its a yellow gel-like substance. I turned off my phone and literally smashed it into the bottom end and pulled it out and it was COVERED with lint. I did this probably 30 times and was AMAZED at how much lint came out. Now the phone charges like new. I would highly recommend buying that stuff before investing in a new phone. You can really jam it in, even to the point where it breaks off. Then it will reattach to the main mass so you can pull it out. Good luck!

Solution 3:

As others mentioned here, the problem is most likely dust and lint in the connector interfering with the data pins. It will prevent charging while connected to a computer.

I had the same problem and fixed it by folding over some Scotch tape, sticky side out, and sweeping it inside the connector until the lint was cleared. Then I inserted and removed the cable connector about 20 times just to make some friction and clear the pins and that did the trick (be sure you unplug the USB side from the computer for that).