iPhone 6 Plus Update System error code 4014 troubleshooting

iPhone 6 Plus mobile phone Update System error code 4014 troubleshooting

Machine model: iPhone 6 Plus.
Malfunction: mobile phone Update System error code 4014.
Peer expansion, mobile phone Update System error code 4014.

iPhone 6 Plus mobile phone flash error code 4014 fault repair Figure 1.

iPhone 6 Plus mobile phone flash error code 4014 fault repair Figure 2.

Maintenance process:
Update System reported an error of 4014 before the progress bar came out, and SN was recognized when Recovery mode was expanded, which was usually caused by the problem of USB chip leading to CPU. when disassembling the machine, it was found that it was UMT motherboard, and the USB chip U1700 was removed to measure diode value leading from PAD to CPU, and AP _ to _ tristar _ ACC _ was found.

iPhone 6 Plus mobile phone flash error code 4014 fault repair Figure 3.

iPhone 6 Plus mobile phone flash error code 4014 fault repair Figure 4.

iPhone 6 Plus mobile phone flash error code 4014 fault repair Figure 5.

iPhone 6 Plus mobile phone flash error code 4014 fault repair Figure 6.

PCB circuit defect, find the external connection point or dig the light board to find the via hole point of the line. AP_TO_TRISTAR_ACC_UART6_TXD is directly connected to the outside without passing through other components. when digging AP_TO_TRISTAR_ACC_UART6_TXD, it was found that there was a via hole point beside the card slot, and Jump wire was dug.

iPhone 6 Plus mobile phone flash error code 4014 fault repair Figure 7.

iPhone 6 Plus mobile phone flash error code 4014 fault repair Figure 8.

iPhone 6 Plus mobile phone flash error code 4014 fault repair Figure 9.

iPhone 6 Plus mobile phone flash error code 4014 fault repair Figure 10.

iPhone 6 Plus mobile phone flash error code 4014 fault repair Figure 11.
There is a test point outside AP_BI_I2C0_SDA, which is directly from the test point Jump wire.