1. Inspect for resistance between the rear door speaker terminals using an ohmmeter.
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.
Mazda 6 Service Manual: Generator removal/installation
Warning
When the battery cables are connected, touching the vehicle body with
generator terminal B will generate sparks. This can cause personal injury, fire,
and damage to the electrical components. Always disconnect the battery negative
cables before performing the following operation.
...
Mazda 6 Service Manual: Bright-Metal Maintenance
Use tar remover to remove road tar and insects. Never do this with a knife
or similar tool.
To prevent corrosion on brightmetal surfaces, apply wax or chrome preservative
and rub it to a high luster.
During cold weather or in coastal areas, cover bright-metal parts with a
coating of ...