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 AdjusterTransaxle Fluid Temperature (Tft) Sensor Removal/Installation [FS5 A EL]
WARNING:
A hot transaxle and ATF can cause severe burns. Turn off the engine and wait
until they are cool.
1. Remove the primary control valve body.
a. Remove the battery cover..
b. Disconnect the negative battery cable.
c. Remove the aerodynamic under cover NO.2..
d. Clean ...
Electrical System
Electrical Parts
Battery cable
Before disconnecting connectors or removing electrical parts, disconnect
the negative battery cable.
Wiring Harness
To remove the wiring harness from the clip in the engine room, pry up the
hook of the clip using a flathead screwdriver. ...
Back Up Light Switch Removal/Installation [A26 M R]
1. Disconnect the negative battery cable.
2. Disconnect the back-up light switch connector.
3. Remove the aerodynamic under cover No.2..
4. Remove the back-up light switch with the gasket.
5. Install a new gasket and the back-up light switch to the transaxle case.
Tightening torque ...