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: Ignition switch inspection
1. Disconnect the negative battery cable.
2. Remove the column cover. (See COLUMN COVER REMOVAL/INSTALLATION)
3. Disconnect the ignition switch connectors.
4. Inspect for continuity between the ignition switch terminals using an
ohmmeter.
If not as specified, replace the ignition switch.
...
Mazda 6 Service Manual: Temporary Spare Tire
Inspect the temporary spare tire at least monthly to make sure it is properly
inflated and stored.
NOTE
The temporary spare tire condition gradually deteriorates even if it has not
been used.
The temporary spare tire is easier to handle because of its construction which
is lighter and small ...