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820-03286 (Air A3114 2024 M3) with no keyboard/trackpad

2informaticos

2informaticos

Administrator
Staff member
Not sure which chip may be involved only with this issue.
Sometime bad flex can cause such problem; you've said already tested.
T

Thread 'Macbook Air M2 (a2681) - Touchpad / Keyboard Issue - LID'

I am working on a customer's Macbook Air M2 (a2681), whenever the lid is closed and re-opened the keyboard and touchpad stop working until the system is force restarted. If I manually put the system to sleep, the keyboard and touchpad continue to work after waking it up.

I checked the LID sensor for any corrosion or damage and it, along with the rest of the system, look in excellent condition with no signs of liquid spill or corrosion anywhere.

I came across another thread that mentioned AMR_LEFT_OR_ND_1V8, so I tested it at RR300 on the motherboard. With the lid closed it reads 0v, when...

One friend mentioned he directly changed all small chips related with trackpad; the ones placed under the border shield, near the connector.
 
sekidata

sekidata

Member
Because that's where the original liquid damage occurred, I already replaced all small chips near the connector (level shifters and load switches) from a donor board.

So you're saying that at this point nobody understands the trackpad/keyboard/haptic circuitry and bus signals enough to pinpoint a failure here.
 
sekidata

sekidata

Member
Update: I finally figured this one out. For haptic feedback and the keyboard to work, the interrupt signal IPD_MCU_INT_CONN_L must be fully functional, in addition to the 4 SPI bus lines. The interrupt signal from the CPU (IPD_MCU_INT_L ) was there, but the level shifter UT340 was not correctly translating the signal to the trackpad. Replacing UT340 a second time restored haptic feedback and keyboard function.

An oscilloscope really was a must in tracking down this hard-to-diagnose loss of function.
 
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