1. Start the on-board diagnostic test mode.
2. First press the POWER button, then simultaneously press AUDIO CONT button for 2 seconds or more.
Caution
3. To stop the on-board diagnostic test mode, turn the ignition switch to the LOCK position.
Mazda 6 Service Manual: Rear door lock actuator inspection
Door Lock Actuator
1. Disconnect the front door lock actuator connector.
2. Apply battery positive voltage to the front door lock actuator terminals
and inspect the operation of the front door lock actuator.
If not as specified, replace the front door lock actuator.
With double locking ...
Mazda 6 Service Manual: Control system
L.H.D.
R.H.D.
...