You might have polarity problem if your Sub doesn’t seem to work properly . The positive and negative wires are reversed at the plug And here’s a picture of what I found after taking the top cover off the sub .

 

This may actually be the correct wiring for the subwoofer and it's "phase" with the other speakers in the car, and was probably set this way originally by Mazda. The easiest way to change the subwoofer phase is to change the polarity of the wiring to the sub. You can actually check it yourself with a sound pressure level meter, while using a test tone signal to the speakers.

Here is a good article to read on subwoofers.....

https://wooferguy.com/subwoofer-phase-and-polarity/

 

Your attachment was a good read . But the thing is until you remove the cover on the sub you don’t get to see or possibly catch this problem because you only see the wires on outside of the sub . So this could be why it has never been caught by any one .
I also didn’t see this until I was done replacing the Bose sub with a new JBL sub . And I did use the red wire as positive or + wire to the new unit. Hear two more pictures for additional information .

 

This may not be a "WRONG" thing, and I would NEVER assume anything regarding a BOSE automotive designed system and would contact BOSE direct. I won't get into why they might have done (anyone can do the research and find why) this but please read this thread as more for the purpose of LEARNING then facts.

But maybe reading this complete thread may show a HOW-TO blow up (if you do not know and understand exactly what you are doing) factory designed BOSE amp or system.

 

Why are you assuming that this IS a problem?? The mismatched wire colors may have been done ON PURPOSE by Mazda or Bose......to tune the subwoofer to the complete audio system within the car, by purposely changing the phasing on the subwoofer. That was my reason for linking the article for you to read.

 

We’ll because this is what Mazda had to say .

 

Well looks like you research and may have solved your problem. I did say may. The Mazda info did say to contact A Mazda dealership. And they wanted your VIN .

The response looks like a basic generic service btw, so while it may be correct for your system there is nothing that indicates it to be for your VIN? Unless you redacted it from the response from Mazda?

 

I’ll bet you that there’s 10s of thousands of them wire wrong. But I’m just putting it out there for the very few people that might want to fix it .

 

*I would not want to take your money...
And I am putting it out there that there needs to be better and more complete information. DIY often post "what they think" is correct and accurate without any thought to the consequences of the unverified information. You are also the type that will bring in that document that is not complete and indicates a UNIVERSAL service advisory and want the service shop to follow it and then "beetch" when you get charged for the wrong repair.

So ya call me a Watchdog of accurate acted based and empirical information on several forums.

Some are not ....see picture
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The basic rule of thumb is NEVER EVER use any service related information unless it matches you exact vehicle and even safer your VIN. This is most important regarding all platforms manufactured from about 2015 to present.