How to Fix iPhone 8 Plus Touch ID/Fingerprint Not Working| Chip Level Repair

When Touch ID not working, you can’t use your fingerprint to get into your iPhone, nor can you scan your fingerprint to make purchases. If you’ve already tried setting up Touch ID on your iPhone but it doesn’t let you complete setup or won’t let you scan your fingerprint, go on reading this article to learn what you can do to make Touch ID work. We will share how to troubleshoot and repair iPhone 8 Plus Touch ID/Fingerprint not working by chip level repair, hope you enjoy our sharing.

Step 1 Function Test

Power on the iPhone, the Touch ID is unable to activate, Go to Settings＞Touch ID & Passcode and try to add a fingerprint. iPhone shows the fingerprint cannot be added.

Step 2 Diagnosis

Dissemble the iPhone and diagnosis the home button assembly and screen assembly, both are no problem.

Step 3 Troubleshooting & Repairing

Take off the motherboard and measure the diode resistance of the home button connector J5800, the pin 2 is measured short circuit. The pin 2 supplies 3V power to the home button, and the reasons that can cause it short circuit are defect capacitors or defect power management IC U2700. Next, we will start with troubleshooting the capacitors

Use the hot air gun and tweezers to remove capacitor, one by each time, and remeasure the diode resistance. When removed the capacitor C5804, the diode resistance is measured normal. Replace with new good capacitors and solder well.

Step 4 Reassemble & Test

Reassemble the motherboard and power on the iPhone, Touch ID is enabled, and fingerprint added successfully, Repair completed

Please refer to below detailed video:

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Tools and Materials Used in This Video:

Microscope

Motherboard fixture

Multimeter

Hot air gun

Tweezers

Solder flux

PCB cleaner

Cleanroom wipes