Put iPhone Xs Max on the aluminum alloy pad, use phone opening tools to disassemble the iPhone Xs Max, remove the iPhone display assembly, disconnect the iPhone battery, and then remove the iPhone motherboard.
After observation, we saw that the iPhone motherboard is oxidized and corroded. Use PCB cleaner to clean the iPhone motherboard. Firstly, use cotton to clean the iPhone ear speaker connector, and then clean the iPhone front camera. (Or we can use DA-968 Intelligent Ultrasonic Cleaner to clean the motherboard).
Because the iPhone XS Max was damaged by dropping, so we suspected that the problem is on the connection between the iPhone touch board and RF board, which causes the iPhone touch connector 3 Pin has no resistance value.
Log in to the ZXW dongle to check iPhone schematic diagram, the touch connector 3 Pin have 3.5V touch power supply.
Finally, assemble the iPhone XS Max, turn it on, and test it, now the iPhone touch function is working properly, and all other functions are working well, the problem has been solved.
I hope the above method will help you. If you have other more effective ways to resolve iPhone touch function not working issue, pls let us know in the comments section below.