"I use a multimeter to test the PIN3 TIP TXD to ground. And find that PIN3 TIP TXD is actually shorted to ground at the beginning. After one or two seconds, the resistance between PIN3 TIP TXD and ground remains stable at 4.66K ohm. However, the PIN2 RING RXD is always open to ground."
noalac, I see something similar with my homebuilt cable that works just fine.
I get TIP open to ground. And 4.7 K ohm between RING and SLEEVE.
I have no idea what that means.
But perhaps you have TX and RX swapped. ( that would still pass your cable check. )
regards,
jl.z