Thunderbolt port not working properly.

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Level 1

8 points

Thunderbolt port not working properly.

I foolishly tried to hook up a firewire drive to my 2017 MacBook Pro using a usb dongle and a "firewire to usb" adapter. I don't know why I thought it would work, and it didn't, of course; however, now I can't get the Thunderbolt port to read any usb device that I attach to the usb dongle.

The Thunderbolt port will still transmit power to the MacBook, and it will charge the battery. The other Thunderbolt port still works fine with the usb dongle. It's just the Thunderbolt port that I hooked up to the firewire drive.

I guess I should just be thankful that the first Thunderbolt port works at all and that I have a spare port that's still working normally. Do you think I fried that port when I hooked it up? The drive didn't even spin up or power on!

I've tried resetting SMC and NVRAM, but neither worked. Should I just accept this and be thankful I didn't fry the whole computer, or is there something else I can do to fix the faulty port?

I suppose I just feel dumb for even trying the firewire drive :(

Thanks for any input you guys might have.

MacBook Pro 13", macOS 10.14

Posted on Mar 15, 2019 2:40 PM

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Answer 1

Top-ranking reply

samlark82 Author

Level 1

8 points

Mar 16, 2019 12:19 PM in response to HWTech

Well, wonders never cease. When you asked, "Have you tried another USB-C cable/adapter just in case it fried one of them instead of the port itself?" I thought about how best to test the port that wasn't working. I have just the one USB to Thunderbolt adapter, so I couldn't test the port with a different adapter or cable. That's when it occurred to me.

The little USB dongle that I've been using has a little LED indicator light on one side (which is usually facing up) to show when it's plugged in all the way. That's how I used it before the malfunction started. That's also how I attached it to the good/unaffected port, and it was recognized no problem.

So what I did then was flip the adapter over so that the indicator light was facing down, and I plugged it into the Thunderbolt port that wasn't recognizing the USB flash drive. It popped up on the screen! There it was, just like always.

I don't know why this worked, but everything's normal now. All I have to do to use the USB to Thunderbolt adapter with the original port is plug it in upside down!

Go figure. Could it be that it's only the adapter that's partially fried? I'll probably wind up replacing it just to satisfy my curiosity.

I appreciate the help. Hopefully I won't run in to any more issues. I'm just glad it's working again.

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Answer 2

Mar 16, 2019 11:36 AM in response to samlark82

Always get the good quality electronics since anything else usually skimps on important safety components.

Chances are you will be fine. Since you have just two Thunderbolt ports that means the Thunderbolt ports are part of the Logic Board and not a separate interface board so the most expensive part is already damaged. The power line probably shorted one of the data lines and most likely the Thunderbolt protective circuitry did its job & took the damage to protect the rest of the laptop.

Have you tried another USB-C cable/adapter just in case it fried one of them instead of the port itself?

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Answer 3

DonH49

Level 6

16,716 points

Mar 15, 2019 3:39 PM in response to samlark82

you could disconnect everything and press the power button for 10 seconds. You could connect a thru thunderbolt external , mount it to the desktop then unmount and disconnect it. I'm not sure how you connected that firewire cable using a usb end , makes no sense to me.

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Answer 4

Mar 15, 2019 4:18 PM in response to samlark82

IIRC years ago it was possible to fry a Firewire 400 port by hot plugging a system in Target Disk Mode, but I forget the details now. If you hot plugged the drive into the USB to FireWire 400 adapter, then perhaps it shorted the power line to another pin. Or it could be a poor quality FireWire adapter. I have connected a Firewire 800 device to a 2017 laptop without issues, but I used Apple's own dongles to do it (USB-C to Thunderbolt adapter connected to a Thunderbolt to Firewire 800 adapter).

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Answer 5

samlark82 Author

Level 1

8 points

Mar 15, 2019 4:27 PM in response to HWTech

It was a cheap Firewire adapter. Under $5.00. I thought about getting the Apple adapters, but I thought I could save some money. I took my chances, and it didn't pan out.

Even if that Thunderbolt port never transfers data again, do you think it's safe to continue using it for charging? I don't have a lot of peripherals, and most of the stuff I do have works fine with the one remaining port using the usb to Thunderbolt dongle.

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Answer 6

samlark82 Author

Level 1

8 points

Mar 15, 2019 3:45 PM in response to DonH49

Thanks, I'll try that. Oh, and I used one of these silly little adapters to connect firewire to usb.

I feel dumb.

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Answer 7

Mar 16, 2019 2:12 PM in response to samlark82

So what I did then was flip the adapter over so that the indicator light was facing down, and 
I plugged it into the Thunderbolt port that wasn't recognizing the USB flash drive. It popped 
up on the screen! There it was, just like always.

If you are using a single cable then you are using other pins on the Thunderbolt port which are undamaged. If you have a USB-C cable and another adapter here, then perhaps the cable is damaged instead of the Thunderbolt port. Some cables may have a protective fuse or circuit. Regardless you will need to be careful using the damaged port for data (especially using Thunderbolt) or for video output.

Glad you have some functionality on the other port.

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Thunderbolt port not working properly.

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