How to fix a dimmed Auto-Lock setting on iPhone

How to back up your iPhone or iPad
How to back up your iPhone or iPad (Image credit: Joseph Keller/iMore)

You're taking a class at the local adult education school about how to use your iPhone. Things are going great, except that as you try to follow along, the iPhone screen keeps turning off every 30 seconds.

You're smart enough to go to the Auto-Lock setting and change it to something longer. But the Auto-Lock control is dimmed, which means you can't change it. Now what?

Squeezing juice

The biggest use of your iPhone's battery is keeping the screen lit. That's why doing things like reducing the screen's brightness and shortening the time before the screen locks (via the Auto-Lock setting) can extend the amount of time that occurs between charges.

And if your iPhone's battery is more than a couple of years old, proactively turning on Low Power Mode can squeeze every bit of power from the battery over a longer period of time, helping you get through the day when recharging may not be an option.

Trouble is, you may not have realized that one of the features of Low Power Mode is to set Auto-Lock to 30 seconds...and lock it. So here's how to unlock it.

  1. Tap Settings.
  2. Tap Battery.
  3. Turn off Low Power Mode.

Low Power Mode (Image credit: iMore)

Now, if you want to change the Auto-Lock setting, you can.

  1. Tap Settings.
  2. Tap Display and Brightness.

Display and Brightness (Image credit: iMore)
  1. Tap Auto-Lock.
  2. Tap a length of time before your iPhone locks.

Auto Lock Screenshot (Image credit: iMore)

Any other weirdness?

If your iPhone is behaving in unexpected ways—for example, is Siri suddenly ignoring you?—be sure to check out Apple's support document that lists the features of Low Power Mode.

Mike Matthews

Mike Matthews is a writer at He has used Apple products all the way back to the Apple II+. He appreciates no longer having to launch apps by loading them from a cassette tape recorder.