All doors lock automatically when the lock side is pressed. They unlock when the unlock side is pressed.
Driver's door

Front passenger's door

To lock all the doors from an open front door, press the lock side of the door lock switch and then close the door.
NOTE
When locking the doors this way, be careful not to leave the key inside the vehicle.
Locking, Unlocking with Transmitter
Auto Lock/Unlock FunctionMazda 6 Owners Manual: Clock spring inspection
1. Remove the clock spring.
2. Inspect for continuity between the clock spring terminals using an
ohmmeter.
If not as specified, replace the clock spring.
Note
When the vehicle-side connector of clock spring is disconnected,
the terminals 1A,1B, 1C and 1D are shorted to prevent ...
Mazda 6 Owners Manual: Panel light control switch inspection
1. Connect the connector to the panel light control switch.
2. Connect the negative battery cable.
3. Measure the voltage at the panel light control switch using voltmeter.
When inspecting terminal B for continuity, disconnect the panel light
control switch connector.
4. If the value are ...