Radio station snafu in Seattle bricks some Mazda infotainment systems

I built telematics solutions a few jobs ago. The very simplified version is that the head unit loaded this image into it's cache and tried to decode it, hit the software bug, locked up and watchdog rebooted. The first thing it does when it reboots is tries to decode the image, and locks up and reboots, forever.

The actual manufacturer of the radio (control unit/whatever) may be able to fix it on a bench with special test harnesses, but if it's stuck in a boot loop there likely isn't any way for them to erase or update the firmware on it, as the CAN accessible updater likely requires the system to be running.

So maybe not technically bricked, but for all useful purposes these can't be field repaired.

If I was the OEM of the unit/firmware I'd like to get these back to us ASAP so we could see if we could figure out a way to get them un-stuck without a hardware replacement. But we were a small shop that liked our customers.

There was a 99% Invisible episode about a listener with a 2016 Mazda where the infotainment system would always crash when listening to 99% Invisible episodes. They tracked it down and the character sequence "99%" was the root cause, but at least it didn't brick the system.

https://99percentinvisible.org/episode/ ... zda-virus/

It seems like that revision of infotainment systems was real shoddy.

I’m not so certain…. I had a 2016 Mazda CX-3 and my wife still has a 2016 CX-5. Both of our cars had failures exhibiting identical symptoms as described in the article. In fact, it happened twice on my CX-3, but the failure the second time seemed to a little different. There is a button combination you can press to force a reboot. Doesn’t help the problem. I tried disconnecting the battery for an hour and that didn’t work either. In all cases, in my experience, the rear view camera continued to work even while the computer was constantly rebooting. I believe the display itself may have two inputs, one for the camera and one for the head unit, and it switches between them when you put the car in reverse. Either that or the camera system is somehow operating a lower level than the rest of the infotainment system and runs Independently of it.

The second failure I had on my CX-3 was odd. FM radio continued to operate at all times, even during the reboot process, but I was unable to change stations, inputs, or even the volume (mute still worked). The screen would cycle through the usual animations during the boot process. Eventually, the FM radio stopped worked, and later still, the display quit showing the reboot animations. You’d still see a little flicker of the back light to tell when it was rebooting. Even in this state the rear-view camera display kept working as intended.

Both cars were still under original factory warranty at the time and all three CMU replacements were covered.

Someone asked earlier and I’ve read on the Mazda forums that Johnson Controls developed the Infotainment system in these. If true, then odds are good that they did both the hardware and software work here. The problem can’t simply be flashed away with a firmware update. My dealer tried for several hours and the system reboots before you can even access the menu to start the flash. There’s no safe mode from which you can run the flash process, nor will it boot from a USB or anything. You can only run the updates after the system successfully boots into the OS and you can access the normal config menus. From what I can see, you’d either need to access a JTAG header like they’d use in the factory or a way to physically replace the cache memory with the offending file to have any hope. Even reflashing via JTAG might not do it if it doesn’t wipe the cache.

I built telematics solutions a few jobs ago. The very simplified version is that the head unit loaded this image into it's cache and tried to decode it, hit the software bug, locked up and watchdog rebooted. The first thing it does when it reboots is tries to decode the image, and locks up and reboots, forever.

The actual manufacturer of the radio (control unit/whatever) may be able to fix it on a bench with special test harnesses, but if it's stuck in a boot loop there likely isn't any way for them to erase or update the firmware on it, as the CAN accessible updater likely requires the system to be running.

So maybe not technically bricked, but for all useful purposes these can't be field repaired.

If I was the OEM of the unit/firmware I'd like to get these back to us ASAP so we could see if we could figure out a way to get them un-stuck without a hardware replacement. But we were a small shop that liked our customers.

There was a 99% Invisible episode about a listener with a 2016 Mazda where the infotainment system would always crash when listening to 99% Invisible episodes. They tracked it down and the character sequence "99%" was the root cause, but at least it didn't brick the system.

https://99percentinvisible.org/episode/ ... zda-virus/

It seems like that revision of infotainment systems was real shoddy.

I’m not so certain…. I had a 2016 Mazda CX-3 and my wife still has a 2016 CX-5. Both of our cars had failures exhibiting identical symptoms as described in the article. In fact, it happened twice on my CX-3, but the failure the second time seemed to a little different. There is a button combination you can press to force a reboot. Doesn’t help the problem. I tried disconnecting the battery for an hour and that didn’t work either. In all cases, in my experience, the rear view camera continued to work even while the computer was constantly rebooting. I believe the display itself may have two inputs, one for the camera and one for the head unit, and it switches between them when you put the car in reverse. Either that or the camera system is somehow operating a lower level than the rest of the infotainment system and runs Independently of it.

The second failure I had on my CX-3 was odd. FM radio continued to operate at all times, even during the reboot process, but I was unable to change stations, inputs, or even the volume (mute still worked). The screen would cycle through the usual animations during the boot process. Eventually, the FM radio stopped worked, and later still, the display quit showing the reboot animations. You’d still see a little flicker of the back light to tell when it was rebooting. Even in this state the rear-view camera display kept working as intended.

Both cars were still under original factory warranty at the time and all three CMU replacements were covered.

Someone asked earlier and I’ve read on the Mazda forums that Johnson Controls developed the Infotainment system in these. If true, then odds are good that they did both the hardware and software work here. The problem can’t simply be flashed away with a firmware update. My dealer tried for several hours and the system reboots before you can even access the menu to start the flash. There’s no safe mode from which you can run the flash process, nor will it boot from a USB or anything. You can only run the updates after the system successfully boots into the OS and you can access the normal config menus. From what I can see, you’d either need to access a JTAG header like they’d use in the factory or a way to physically replace the cache memory with the offending file to have any hope. Even reflashing via JTAG might not do it if it doesn’t wipe the cache.