Huawei P20 - SIM Card Detection Failure; Maintenance Process

EML-L29V100R001 Advanced Maintenance Manual V2.1
INTERNAL
2019-6-25
Huawei Confidential
Page 25 of 67
4.2 SIM Card Detection Failure
4.2.1 Maintenance Process
SIM card detection
failure
Replace the SIM card
Test the SIM card
Replace the card tray
Pass
Fail
The original SIM
card is damaged
Test the SIM card
Pass
Fail
Replace the card tray
Replace the card slot
Replace the
card holder
Signal
detected
Pass
Pass
Pass Pass
Pass
Damage
found
Fail
Fail
Fail
Fail
Fail
Test the time
sequence
Software is faulty.
Try formatting the
phone
Check components
on related circuits
Check the
main chip using an X-ray
machine
Replace the main chip
Replace defective
components
Visually
inspect the card
slot
No damage
No
signal
Test GPIO_
SIMx_DET
Test the
signals of all pins
of the SIM card
holder
Test the
impedance of all
pins of the SIM
card holder