Chris Breen describes his process for [Troubleshooting a battery-sucking iPhone 4S][1].

By using [*System Activity Monitor*][2], a low-cost app, he discovered a problem with iCloud contact syncing that was causing *dataaccessd* (a process) to continuously crash. His fix was to wipe the phone and do a fresh (not restored) installation, then reinstall his data and apps. 

![image of System Activity Monitor app Processes screen][3]

I used the same process to solve my own iPhone 4 overheating issue when iOS 5 was first released. Fortunately, iCloud makes it relatively painless process to migrate data to a *new* phone.


  [1]: https://www.macworld.com/article/1163200/troubleshoot_iphone4s_battery.html
  [2]: http://itunes.apple.com/us/app/system-activity-monitor/id306192663?mt=8
  [3]: https://i.sstatic.net/2NlHG.png