1. Remove the rear seat cushion.
2. Remove the bolts.

3. Remove the rear buckles.
4. Install in the reverse order of removal.
Front buckle removal/installation
Seat belt inspectionMazda 6 Service Manual: Ignition switch inspection
1. Disconnect the negative battery cable.
2. Remove the column cover. (See COLUMN COVER REMOVAL/INSTALLATION)
3. Disconnect the ignition switch connectors.
4. Inspect for continuity between the ignition switch terminals using an
ohmmeter.
If not as specified, replace the ignition switch.
...
Mazda 6 Service Manual: Inspection of sst (deployment tool)
Use the SST (Deployment tool) to deploy a live (undeployed) air bag
module or pre-tensioner seat belt before disposing of it.
Before using the SST (Deployment tool), inspect its operation.
Inspection Procedure
Follow the steps below to verify that the SST (Deployment tool) is
operatin ...