Is there a way to test for faults (power supply and/or data transfer) in a possibly failing USB-C cable, by plugging each end into different ports on the same machine (2018 MBP) and sending traffic from one port to the other?
More info :
This question is about charging problems on a 2018 MBP with these new two-part chargers (with a separable USB-C that plugs into the machine on one end and a port on the power adaptor on the other).
Charging on my macbook is getting spotty, with
- Instances where I plug in and get the nice normal beep that indicates you're getting a charge,
- instances where I don't get the beep (and I get an icon change in the menu bar to say I'm plugged in, but also a note saying that the battery is not charging), and
- instances where that beep strangely happens every few seconds.
Suspects are going to be
- the USB-C cable to the power adaptor,
- the power adaptor itself,
- the power cable,
- the USB-C ports, and
- the motherboard.
My money is on the USB-C cable. The geniuses don't have any diagnostics for cables or adaptors, just for the motherboard and USB-C plugs. We ran what diagnostics there were and although they weren't conclusive, they supported my prior that the problem is somewhere in the cables. USB-C is the flimsiest of the cables, and gets the most abuse, so it's the prime suspect.
I can isolate the old-fashioned way, by borrowing some other new mac owner's power supply and cables, but
- The issue is pretty come-and-go, making it hard to reproduce
- It would generally be neat if the symmetry and "universality" of USB-C made it possible to test cables through recurrent connections from one port on a machine to another on the same machine.
- If this recurrent intra-machine solution existed, it would also accelerate troubleshooting a lot.
Beyond the specific wonky q. of testing a cable through within-machine connections, any advice on this power supply issue generally? I'm still on warranty, and I was relieved to find that it will cover not just the machine and its adaptor, but the USB-C cables leading to the adaptor. But if I must go back to the Store or ship my machine, I want to go with confidence about what specifically is wrong.