1. Disconnect the negative battery cable.
2. Remove the column cover. (See COLUMN COVER REMOVAL/INSTALLATION)
3. Disconnect the key reminder switch connector.
4. Inspect for continuity between the key reminder switch terminals using an ohmmeter.
Mazda 6 Service Manual: Automatic Transaxle Controls
Various Lockouts:
Indicates that you must depress the brake
pedal and hold in the lock-release button to shift (The ignition must be switched
ON).
Indicates the shift lever can be shifted
freely into any position.
Indicates that you must hold in the lock-release
button to shift.
N ...
Mazda 6 Service Manual: Front 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 ...