MacBook Pro turn off when unplugged an external monitor

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Level 1

4 points

MacBook Pro turn off when unplugged an external monitor

My mac only works when I connect an external HDMI monitor and this monitor is turned on. When I turn off the monitor or unplug the HDMI cable, my mac after a minute starts heating up and its fans make noise. Then the mac shuts down. It happens with the battery or the connected power source.

I have done a complete maintenance and cleaning. I've changed the thermal paste, cleaned the fans, even bought a new battery, just reset my mac and still have the same problem.

Any idea what could be going on?

MacBook Pro 15″, macOS 11.7

Posted on Jun 7, 2023 7:35 AM

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Answer 1

Top-ranking reply

Sharhari

Level 5

6,293 points

Jun 7, 2023 9:54 AM in response to intijosue

Since there is a shutdown / restart, Checking the log for the shutdown cause should help to troubleshoot.

Below command in terminal should help to get the reason.

log show --predicate 'eventMessage contains "Previous shutdown cause"' --last 24h

"24h" is the duration, adjust to your approximate time when this occurred.

Also, check Activity Monitor to see the max CPU/RAM usage when you disconnect/unplug HDMI cable.

Have you checked if this occurs in safe mode too?

Start up your Mac in safe mode - Apple Support

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Answer 2

Sharhari

Level 5

6,293 points

Jul 22, 2023 3:03 AM in response to intijosue

See: https://eclecticlight.co/2017/02/28/mac-shutdown-and-sleep-cause-codes/

some of the known codes for the shutdown cause.

" -128 unknown, possibly battery is at the end of its life, but can also occur when the SMC initiates an automatic restart following a kernel panic."

Since you mentioned you brought new battery, did you had this problem with original battery that your MacBookPro came with?

Also, what is the MBP model?

Suggest you to Use Apple Diagnostics to test your Mac - Apple Support and visit/get it checked with Apple Support/Service. {Mac Repair & Service - Apple Support}

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Answer 3

intijosue Author

Level 1

4 points

Nov 22, 2023 1:05 PM in response to Sharhari

Thank you so much for your help. Sorry for the late response, I hope you can still helping me.

In case -128 is the cause of my Mac's problem, what should I do?

I should mention that I already had this problem with the original Mac battery. I decided to change it for a new original one and the problem continues. My mac's model is A1398.

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Answer 4

intijosue Author

Level 1

4 points

Jul 20, 2023 8:01 PM in response to Sharhari

Thank you so much for your help.

Here's the log for the shutdown cause. It says "shutdown cause: -128"

2. In safe mode this shutdown doe not happen.

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MacBook Pro turn off when unplugged an external monitor

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