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User profile for user: christospappas
christospappas Author
User level: Level 1
31 points

16-inch MacBook Pro Bluetooth issue

I bought the new 16-inch MacBook Pro when it first came out and was happily using it until a week later my bluetooth stopped discovering devices, in particular my Magic Mouse and iPhone. I tried everything from resetting nvram, smc, resetting the bluetooth module, removing bluetooth.plist, downloaded bluetooth explorer and reset a bunch of settings etc and even went to the extent of completely formatting the computer and installing osx from scratch to no avail. Hardware diagnostics showed no hardware issues as well. The bluetooth device was showing up fine in System Report but it just wasn't discovering anything. I have a work laptop (2017 MacBook Pro) which I use side by side and it was working fine.


Long story short, I was able to replace the device at the Apple store I bought it at since it was within the 14 day return policy window. So I put it down to just being unlucky.


It's been a few weeks since then and I now have the same issue with the replacement laptop. This time though I think I know what triggered it.


I have a CalDigit dock that I use for my work laptop and occasionally have a usb bluetooth device attached to it for some work I do in virtual machines. The issue occurred when I connected my new MacBook to the dock along with the bluetooth dongle. The usb bluetooth dongle worked fine however when I disconnected the thunderbolt dock from the MacBook I noticed the bluetooth icon in the top right hand corner changed to an icon with a zigzag across it, obviously due to bluetooth device being disconnected.


Since disconnecting the external bluetooth device I'm having the same issue as I had previously, my MacBook Bluetooth device won't find any devices and is not recognized by other bluetooth devices like my iPhone/other MacBooks. I've gone through the whole process as before, and have resorted to a clean install of osx to no avail. I've even compared bluetoothd console logs between the working MacBook I have and the now broken one, the only difference is the working MacBook is able to detect devices when they are advertised, whereas the MacBook Pro 16-inch does not.


Digging into this, it seems as though OSX by default switches to any attached USB bluetooth device when it's plugged in and then when disconnected, it reverts back to the onboard device. This works fine on my old MacBook as I've been using the USB dongle for a while now without any issues. I initially thought that there may be a software issue with the internal bluetooth device not switching back properly but I would have thought a clean install would have fixed it so there must be some sort of hardware issue specifically with the new MacBook Pro 16-inch.


I'm pretty frustrated now as I've now gone through two 16-inch MacBook Pro's with bricked bluetooth devices that I'm fairly certain was caused by connecting an external bluetooth dongle via thunderbolt. I'm pretty sure onboard devices shouldn't die just because a third party device was connected/disconnected.


Has anyone come across this yet with the new MacBook Pro 16-inch? I'm going to visit the Apple store tomorrow to see what they can do but I'd prefer if I didn't have to send my laptop away and just find a fix myself if there is one. If not, I thought it'd be good to post my experience here in case anyone else comes across this.

MacBook Pro 16", macOS 10.15

Posted on Dec 14, 2019 2:09 AM

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User profile for user: fabian259
fabian259
User level: Level 1
13 points

Posted on Jul 6, 2020 5:25 AM

Here is a summary of the whole thread:


TL;DR:


  • It's apparently possible to unfix the problem with a BT 2.0 dongle
  • For those that are scared to break it again (after logic board replacement OR BT 2.0 fix), they can run a NVRAM command to never switch BT controllers again (need to re-run after NVRAM reset): 


sudo nvram bluetoothHostControllerSwitchBehavior="never"


Might be best to put that in a startup script and only change if needed.


  • It seems to have to do with Power Management and seemingly a EFI firmware bug introduced in Catalina as it's not possible to break Mojave in the same way.


So in summary it's several factors that came together here to create this bug:


  • a) A likely firmware bug in the EFI in Catalina.
  • b) A pretty unsafe default for switching Bluetooth controllers - which most users likely don't want anyway.
  • c) Maybe: A CSR USB controller using the exact same chip as the internal one. (if I am able to unbreak my device, I will try to re-break with a Broadcom 4.0 device, too)


Long version:


I have been bitten by the Bluetooth bug, too that breaks the internal Bluetooth module on Mac Book Pro 16inch if you accidentally plug in an USB CSR 4.0 Bluetooth dongle.


  • It seems to not happen on Mojave - so it's also related to a driver bug in Catalina regarding power management.
  • It happens in the first place because the nvram default behavior is to switch over to external Bluetooth by default.


The symptom is:


  • The Bluetooth chip gets too little power and hence fails to connect to devices and if it does connection is spotty. While on MacBook Pro 16inch it completely fails, other Macs can have bad Bluetooth behavior that is "spotty".


  • The solution of AppleRepair so far has been to completely replace the logic board, which fixes it till the next Dongle is plugged in and obviously is quite costly for a pure software bug.


Several observations:


  • The current theory is that the internal firmware mixes up the external CSR chip for it's own and saves the power requirement of the external chip (which is less as its powered by BT) and then uses this for the internal chip.


  • a) It is highly debatable to make the switch over to external dongle the default for all users if the functionality is usually only wanted by a handful of developers that develop Bluetooth LE applications. In fact it also breaks it for iOS developers and everyone that wants to use a Dongle to use with a VM:



  • Fortunately that is easily remedied with a nvram command to change the behavior. It would be great if Apple changed this in the next minor Catalina release by default to not switch over to external Bluetooth automatically, but make it an option to select the Controller (like you can do with Bluetooth Explorer). The setting could be stored and automatically be applied after every reboot to what the user configured. That would prevent the bug in probably most user cases until a proper fix can be found.


  • b) It is unclear if a pure software fix could fix this as per the reports the issue remains once it has happened even if you boot into Windows / Bootcamp. However it is seemingly possible (per the above accepted answer) to unfix that issue with an older CSR Bluetooth 2.0 dongle. This probably helps, because it has a different power requirement as it predates Bluetooth LE and hence the MacBook FW gives the internal Bluetooth chip more power again.


  • c) Someone tried to port the Bluetooth drivers from Catalina to Mojave and it did not work.This points to the fact that it likely is an EFI / soft FW update that broke this in Catalina and not a pure software bug.


Overall it seems Apple would have several ways to fix / work around this:


  • Fix the EFI to fix the PM bug. (that gives hope that it can be fixed 100% and also restored affected devices without logic board replacement)
  • If that fix takes a while to do, at least change the default and put out a changelog for those few that need to use an external Bluetooth dongle to replace the internal one.
  • Create a program that does whatever the diagnostics on the Apple Wifi in the repair shop does to reset the firmware to sane values.
  • Create a device to emulate the USB behavior of a 2.0 Bluetooth device to fix broken devices [unlikely as that is].


In theory VirtualHere + ZeroTier could be used to share a BT 2.0 dongle from one machine on the internet to another one and unbreak something remotely. (not sure if that would work in practice though as emulation is not perfect. Though I know that Bluetooth over Internet works well as that is ironically how I broke my BT in the first place as I needed a dongle for bluetooth-over-internet)

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User profile for user: hairdresser06
hairdresser06
User level: Level 1
4 points

Jun 3, 2020 11:36 AM in response to Loner T

There is unfortunately no way to reach out to real engineers. I've tried 3 different ways. The only thing you can do is talk to people following processes and workflow - so same as AI without I - which, surprisingly, don't have any escalation process ! And no manager available ! This is what I've been told over the phone: no supervisor no manager. I've as such asked for the phone records - as per GDPR law - because it definitely worths making this information public: it is so cool to work at Apple, you are like a freelancer, no manager nor supervisor.

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User profile for user: JuJuBoSc
JuJuBoSc
User level: Level 1
4 points

Jun 3, 2020 11:40 AM in response to Loner T

I'm not hoping for an engineer to come here with a solution, but afaik this issue is not well known yet, I believe many users have the same problem without even knowing what caused it.


I understand not many people use a bluetooth dongle, it myself happened by accident as many others by simply plugin it to my dock that had a bluetooth dongle at this moment, I'm glad I figured fairly quick it was related to that dongle and found that thread.


What I would like to know is, does any bluetooth dongle work at all?

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User profile for user: jeremías49
jeremías49
User level: Level 1
4 points

Jun 4, 2020 3:06 AM in response to aLegend2k

I know right? At my job we bill by the hour. Wonder if Apple is going to compensate me for the money I have lost trying to connect my keyboard to my brand new MBP while they don’t even acknowledge the issue. This smells like a big problem when a lot of people realise they lost BT in their $3k+ laptops by connecting a dongle.


All my tests were done using an ASUS 4.0 Dongle but the culprit was that CSR 4.0 Dongle.

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User profile for user: Loner T
Loner T
User level: Level 9
59,513 points

Jun 4, 2020 6:54 AM in response to jeremías49

jeremías49 wrote:

Issue persists on Bootcamp and after reinstalling macOS. It's either a hardware or firmware issue.

Does WiFi work properly on the Mac which no longer has BT? The BT/WiFi is an integrated module.

Hopefully a it can be fixed via software update, otherwise I foresee quite a large number of product recalls.

No worries. 😉. Apple has a lot of experience in managing large recalls since 2008.

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User profile for user: AntiHawk
AntiHawk
User level: Level 1
18 points

Jun 4, 2020 8:45 PM in response to JuJuBoSc

I used different one to bring it back working.

the one that I got bt back working again is generic rebranded usb bt dongle by my local electric store:

"Bluetooth USB Dongle V2.0+EDR "

FCC ID: rl9-hcbd-004


MacOS system information on USB:

Bluetooth HCI:

  Product ID: 0x0001

  Vendor ID: 0x0a12  (Cambridge Silicon Radio Ltd.)

  Version: 48.39

  Speed: Up to 12 Mb/s

  Location ID: 0x14100000 / 1

  Current Available (mA): 500

  Current Required (mA): 0


  Extra Operating Current (mA): 0





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User profile for user: Dalogan72
Dalogan72
User level: Level 1
4 points

Jun 7, 2020 9:52 AM in response to AntiHawk

@AntiHawk, it works!!!!! brother thanks so much. Amazing. I did use a different bluetooth 2.0 as well the cheap one you fet from amazon or ebay, https://www.amazon.co.uk/gp/product/B00IMQ58NI/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1

I did all your steps but I do add something to your amazing work, dude amazing you are.

number 4 I have manage do fix the issue without doing it. in case you got a egpu you guys have to remove it. For some reason I dont get, it does not work if you got it on (maybe power source?). Also in my case I manage to reproduce the failure only 3 times, in all of them I got to nvram and smc. I am just talking in my cases. Like you I used an android device.


Bluetooth aslo works now in bootcamp


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User profile for user: felipejfc
felipejfc
User level: Level 1
26 points

Jun 7, 2020 12:39 PM in response to Loner T

holy sh*t, just want to confirm that after 2 months with no builtin bluetooth I managed to fix mine by doing @AntiHawk procedure using an old cheap bt 2.0 device.


I basically connected BT 2.0 device into my pc (and unplugged it, didn't connect to anything just let it search), opened terminal and deleted bluetooth plist, then reboot mac and cleaned nvram.


After this it started working again, I didn't even need to plug the usb bt again...


thanks @AntiHawk!


=== EDIT


I think that this basically shows that this is some really hard to debug software bug rather than short circuit into bt internal module like some said, it does make sense since bt and wifi use the same internal chip, so breaking one without breaking the other would be kinda crazy...

I think we just helped apple save couple hundred thousand U$D in replacement costs

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16-inch MacBook Pro Bluetooth issue

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