Ambient light sensor

input.ambient-light-sensorHands-on · automaticHigh confidence

How it tests

The tester covers the sensor for three seconds, with a countdown, then uncovers it. The tool polls applesmc's light reading five times a second (its two values summed). The uncovered level is the average over the first 1.5 s; under 3, the room is too dark and the tester shines a phone's flashlight on it instead. The quick pass only notes a reading (uncertain).

How it decides

Supported: the level drops by at least half and at least 2 counts (with the flashlight: rises by its own level and at least 3), holds 3 s, and comes back at least halfway and 2 counts once uncovered. Partial: followed the cover but didn't come back within 12 s, or never moved and the tester says they covered it. Failed: no reading, or it stopped during the test. Not tested (live limit) without the applesmc fix or the install kernel.

How sure it is

A stuck value can't follow a hand.

On a real Mac

On a MacBook Air (13-inch, Mid 2012): 8 dropped to 1, held 3.1 s, back to 8.

What could mislead it

Could fail when it shouldn'tThe tester covers the wrong spot and answers that nothing changed: partial for a working sensor.