Mid-2015 Macbook Pro won't recognize my Thunderbolt Display

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Level 1

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Mid-2015 Macbook Pro won't recognize my Thunderbolt Display

Hello,

I recently purchased a used Thunderbolt display to use both with the 2019 Macbook Pro that I use for work and my personal mid-2015 Macbook Pro. It works great with the 2019, using the adapter for the USB-C port, but my mid-2015 won't recognize it in either port. I tested the monitor with both laptops before purchasing, and it took a few minutes for the display and 2015 to work together, but they did. However, I have not been able to get the 2015 to recognize the monitor ever since. I have not ever used the thunderbolt ports prior to this...is this likely a problem with the ports?

MacBook Pro 15″, macOS 11.5

Posted on Jan 11, 2023 2:51 PM

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Answer 1

Top-ranking reply

Grant Bennet-Alder

Level 10

133,429 points

Jan 12, 2023 6:02 AM in response to MacUs3r4

One issue that comes up with Thunderbolt-2 used only occasionally is that the amount of FORCE required to seat the plug in the jack is surprisingly high.

You must push until essentially All of the metal-end of the cord disappears inside the jack.

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Answer 2

Jan 13, 2023 4:03 PM in response to MacUs3r4

The four times when your Mac looks for a display are listed in my post above. try some of those next.

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Answer 3

Jan 12, 2023 6:03 AM in response to Grant Bennet-Alder

Once the cable-end is seated,

The Mac uses a system that reminds me of “Plug and play” to determine what display is connected, and what its capabilities are.

To get a Mac display to become active, you need the Mac to query the display, and the display to answer with its name and capabilities. Otherwise, the display will not be shown as present, and no data will be sent to the display. "No signal detected" is generated by the DISPLAY, not by the Mac.

This query is only sent at certain times:

• at startup

• at wake from sleep — so momentarily sleeping and waking your Mac may work

• at insertion of the Mac-end of the display-cable, provided everything on that cable is ready-to-go

• hold the Option key while you click on the (Detect Display) button that will appear in Displays preferences (from another display)

so try doing some of those things and see if the display comes alive.

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