Depress the button on the seat belt buckle.
If the belt does not fully retract, pull it out and check for kinks or twists. Then make sure it remains untwisted as it retracts.

NOTE If a belt does not fully retract, inspect it for kinks and twists. If it is still not retracting properly, have it inspected at an Authorized Mazda Dealer.
Fastening the Seat Belt
Front Shoulder Belt AdjusterRelay Block Inspection [With Advanced Keyless Entry And Push Button Start System]
1. Disconnect the negative battery cable..
2. Remove the following parts:
a. Driver-side front scuff plate.
b. Driver-side front side trim.
c. Hood release lever.
d. Upper panel.
e. Shift knob (MTX)(See MANUAL TRANSAXLE SHIFT MECHANISM REMOVAL/INSTALLATION
[G66M-R].)(See MANUAL TRANSAX ...
Manual Transaxle Removal/Installation [A26 M R]
CAUTION:
Secure the steering wheel using tape or a cable to prevent the steering shaft
from rotating after disconnecting the steering shaft. If the steering wheel
rotates after the steering shaft and the steering gear and linkage are disconnected,
the internal parts of the clock spr ...
PCM Inspection [Mzr 2.0, Mzr 2.5]
Using M-MDS
NOTE:
PIDs for the following parts are not available on this model. Go to the appropriate
part inspection page.
CMP sensor
Main relay
1. Connect the M-MDS to the DLC-2.
2. Switch the ignition to ON.
3. Measure the PID value.
...