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i've done a small experiment, soldering a wire on PP20V_USBC_T_VBUS line and injecting 1v...i can read without problem 1v on the connector...so the line from the motherboard connector to the opposite site of the connector is ok,..
but when i insert the cable, there is no voltage at all, power meter doesn't power on, neither by-3200s that show 0v @ 0a
VBUS line doesn't get any voltage in the first moment.
The charger only delivers voltage on the VCONN line of its cable.
That will connect with CC1, or CC2 line; depends of the cable orientation.
If the charger will detect correct impedance on VCONN (CC1, or CC2), it will delivers then 5V to VBUS.