These locks are intended to help prevent children from accidentally opening the rear doors. Use them on both rear doors whenever a child rides in the rear seat of the vehicle.
If you slide the child safety lock to the lock position before closing that door, the door cannot be opened from the inside. The door can only be opened by pulling the outside handle.

Locking, Unlocking with Door- Lock Knob
Trunk LidMazda 6 Owners Manual: Dtc b1318
Caution
When attaching the tester lead to the ABS (ABS/TCS) HU/CM harness
connector, the SST (49 G066 001) must be used. (See ABS (ABS/TCS) HU/CM
INSPECTION.)
Diagnostic procedure
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Mazda 6 Owners Manual: To Decrease Cruising Speed
Press the SET/ switch and hold
it. The vehicle will gradually slow.
Release the switch at the desired speed.
Press the SET/ switch and release
it immediately to adjust the preset speed.
Multiple operations will decrease the preset speed according to the number of
times it is operated.
Decr ...