diode mode check board

会员1244779

I have a question for you with a diode mode. I will be glad if you answer.
When those who repair iphone usually look for a short circuit, the measurement is made with the diode mode. but I usually use the ohm value for years
I have a few questions about the diode mode. I haven't found a complete answer yet.
why with diode mode measurement time red probe GND . the black probe is measuring the signal. Is this because of applying positive voltage to the motherboard in the opposite direction? I did some research. I found out that this is because of the ESD protect diode.
My other question is, for example, the value of 0.060mv came out. I measured the pch 1.05 line here. this value means that there will be a loss of 60mv in the area connected to that line ? For example, the +3.3v value on the standby line is higher with the diode mode. The fact that it is high gives that value that the line generates signals to many places. for example 0.850mv.