1. Disconnect the negative battery cable..
2. Remove the rear door trim..
3. Remove the rear door speaker..
4. Verify the resistance between the rear door speaker terminals.

If not within the specification, replace the rear door speaker.

Without Bose®: 3.4—4.6 ohms
With Bose®: 2.89—3.91 ohms
Rear Center Speaker Removal/Installation
Rear Door Speaker Removal/InstallationCompression Inspection [Mzr 2.3 Disi Turbo]
WARNING:
Hot engines and oil can cause severe burns. Be careful not to burn yourself
during removal/installation of each component.
Fuel vapor is hazardous. It can very easily ignite, causing serious injury
and damage. Always keep sparks and flames away from fuel.
Fuel ...
Gracenote Database (Type B)
When a USB device is connected to this unit and the audio is played, the
album name,
artist name, genre and title information are automatically displayed if there is
a match in
the vehicle's database compilation to the music being played. The information
stored in this
device uses database ...
Stop Vehicle in Safe Place Immediately
If any of the following warning lights turns on, the system may have a
malfunction. Stop the
vehicle in a safe place immediately and contact an Authorized Mazda Dealer.
...