Operating Inspection
1. Verify that the starter operates only when the ignition switch is at the START position with the selector lever in P or N position.
2. Verify that the back-up lights illuminate when shifted to R position with the ignition switch at the ON position.
Continuity Inspection
Caution
1. Disconnect the negative battery cable.
2. Remove the air cleaner component. (See INTAKE-AIR SYSTEM REMOVAL/INSTALLATION.)
3. Disconnect the TR switch connector.

4. Inspect for continuity at the TR switch.

5. Reinspect for continuity at TR switch.
6. Connect the TR switch connector.
7. Install the air cleaner component. (See INTAKE-AIR SYSTEM REMOVAL/INSTALLATION.)
8. Connect the negative battery cable.
Hold switch removal/installation
Transaxle range (tr) switch removal/installationMazda 6 Service Manual: Scheduled Maintenance (U.S.A., Canada, and Puerto Rico)
Follow Schedule 1 if the vehicle is operated mainly where none of the following
conditions (severe driving conditions) apply.
Repeated short-distance driving
Driving in dusty conditions
Driving with extended use of brakes
Driving in areas where salt or other corrosive materials are used
...
Mazda 6 Service Manual: No.9 noise while operating a/c system
Diagnostic procedure
* : If there is gas leakage, air enters into the A/C system. The desiccant
within the receiver/drier absorbs the moisture from the air and becomes
saturated. If the A/C system is used in this condition, the inside of the A/C
compressor will begin to rust due to this ...