SuuntoLink + DM5: Fixing Core Isolation Issues with Suunto's USB Drivers

[yetanotherdeveloper]

If you’ve stumbled upon this post, chances are you’ve tried to get your Suunto watch connected via SuuntoLink, only to be greeted with an error message, a Code 39 in Device Manager, or Windows outright refusing to run the driver.
The reason is that Suunto’s drivers are stuck in 2015 like a bad time capsule.

The Problem:

When Core Isolation is enabled in Windows Defender, SuuntoLink fails to recognize the watch and instead tells you to “install” its driver.
Root cause: A part of the Suuntos USB driver is not certified and thus it is not safe for use.

Suunto uses an FTDI driver for a serial adapter and a port adapter to communicate with the watch. But since they never update anything, we need to fix it ourselves.

The Fix:

1. Install Suunto’s ancient, decrepit drivers

2. Get the latest FTDI drivers

   • Head over to the FTDI Chip website
   • Navigate to Drivers -> D2XX Drivers
   • Scroll to the table and download the latest version for Windows (NOT the executable!)
   • Unzip the folder somewhere accessible.

3. Delete the Suunto FTDI Bus Driver

   • Open PowerShell as Admin
   • Run

     pnputil /enum-drivers
     

     and look for the Suunto driver with ftdibus (NOT the port version) from 2015.
   • Note down the oem name (e.g., oem11.inf).
   • Run:

     pnputil /delete-driver <NAME> /uninstall /force
     

     (Replace <NAME> with the actual oem file, e.g., oem11.inf)

4. Install the Latest FTDI Bus Driver

   • Your driver will now look broken in Device Manager. Perfect!
   • Open Device Manager and locate Universal Serial Bus controllers.
   • Find USB Serial Converter (it may have a warning icon next to it).
   • Right-click on it and select Update Driver.
   • Choose Browse my computer for drivers.
   • Click Let me pick from a list of available drivers on my computer.
   • Click Have Disk….
   • Navigate to the unzipped FTDI driver folder and select ftdibus.inf.
   • Click OK, then select USB Serial Converter.
   • Click Next, Close, and restart your computer.

The Outcome:

Now, your SuuntoLink might still complains that no FDTI driver is installed, but it will work and this message can be ignored.

Suunto, if you’re reading this, update your USB drivers.

Good luck!

[yetanotherdeveloper]

Update – Heads Up After a Windows Update

Just a heads-up for everyone: Windows Updates may silently replace your manually selected FTDI Bus driver with the outdated Suunto version again. Super helpful, right?

How to Spot This:

Open Device Manager. If you suddenly see a
Suunto Sports Instrument with a small warning icon under:

Ports (COM & LPT) or Universal Serial Bus controllers

…then congrats, Windows “fixed” it for you.

The Fix:

• Right-click on Suunto Sports Instrument
• Select Properties
• Go to the Driver tab
• Click Update Driver
• Choose Browse my computer for drivers
• Click Let me pick from a list of available drivers on my computer
• Select Have Disk…
• Navigate to your unzipped FTDI driver folder and choose ftdibus.inf

Hit OK, then choose USB Serial Converter from the list

Click Next, close everything.

️ Note on SuuntoLink:

SuuntoLink might still throw a warning that an “FTDI Driver is needed.”
Just click the little to close it.
(Pretty sure it just searches by driver name rather than checking if the thing actually works.)

Suunto Please

I don’t know if I’m the only one here who’s annoyed, but if others are also tired of this driver mess, maybe it’s time to bring out the pitchforks and torches.

Suunto—it’s probably a day’s worth of work to update that USB driver.

For now, that post’s sitting at like 130 views—maybe most people just disable Core Isolation, don’t use SuuntoLink, or gave up on these dive computers altogether. Who knows. But hey, if this workaround helps even a few folks, that’s a win in my book