Earpiece speaker and sensor assembly affixs to the back of the iPhone X Screen display, and it contains the flood illuminator, which is part of the biometric Face ID security feature. You must transfer it from your old display to your new one as instructed below.
Step 1: Open the iPhone X Display
Remove the two bottom screws. Lay overlapping strips of packing tape over the iPhone's display until the whole face is covered. Soften up the adhesive underneath with a heat gun.
Hold onto your iPhone securely and close the handle of the suction cup to slightly separate the screen from the rear case of the phone.
Slide the opening pick around the top corner of the display. Open the iPhone by swinging the display up from the left side.
Step 2: Display Assembly
Remove five securing the logic board connector bracket, and remove the bracket. Pry the battery connector up from its socket on the logic board. Disconnect the front panel sensor assembly connector.
Disconnect the OLED panel cable connector. Pry the digitizer cable connector up from its socket. Remove the display assembly.
Step 3: Earpiece Speaker and Front Sensor Assembly
Remove the screw on the back of the display assembly and metal grounding clip with screwdriver. Take off two screws securing the speaker/ sensor assembly.
Gently pry under the top edge of the speaker assembly using a spudger, and flip it over—down and away from the top edge of the display.
Soften the adhesive securing the sensors though a heat gun. Twist gently to separate the microphone, while being careful not to strain or damage the flex cable.
Gently wiggle and lift to separate the proximity sensor and flood illuminator module from its notch in the front panel.
Wiggle the ambient light sensor and lift it from its notch in the display. set the iPhone X ambient light sensor on top of the diffuser.
You will need to hold the sensor in position while installing the screws securing the earpiece/sensor assembly.
Finally, remove the iPhone X earpiece speaker and front sensor assembly.
If your iPhone’s auto brightness feature does not work properly after your screen repair, make sure your iPhone is updated to iOS 12. True Tone functionality is disabled after a screen replacement, even when using an original Apple screen.