Inside Trunk Release Lever (Some models)Mazda 6 Owners Manual: Locking, Unlocking the Doors
NOTE
The system may not operate if you are too close to the windows or door
handles.
If the key is left in the following areas and you leave the vehicle,
the doors may be locked depending on the radio wave conditions even if the key
is left in the vehicle.
Around the dashboard
...
Mazda 6 Owners Manual: Rear door speaker inspection
1. Inspect for resistance between the rear door speaker terminals using an
ohmmeter.
If not as specified, replace the rear door speaker.
2. To verify that the rear door speaker outputs sound, apply voltage to the
rear door speaker and release using a 1.5-V battery.
If not outputs ...