1. Disconnect the brake fluid level sensor connector from the master cylinder.
2. Inspect for continuity according to fluid level between the brake fluid level sensor terminals.

If not as indicated in the table, replace the reserve tank.

Brake Switch InspectionParking Brake
CAUTION
Driving with the parking brake on
will cause excessive wear of the brake
parts.
NOTE
For parking in snow, refer to Winter Driving regarding parking
brake use.
Setting the parking brake
Depress the brake pedal and then firmly
pull the parking brake lever fully upwar ...
Side Air Bag Sensor No. 1 Removal/Installation [Two Step Deployment Control
System]
WARNING:
Handling the side air bag sensor improperly can accidentally operate (deploy)
the air bag module, which may seriously injure you. Read the air bag system
service warnings and cautions before handling the side air bag sensor..
1. Switch the ignition to off.
2. Disconnec ...
Contact Authorized Mazda Dealer and Have Vehicle Inspected
If any of the following warning lights or the indicator light turns on/flashes, the system may
have a malfunction. Contact an Authorized Mazda Dealer to have your vehicle
inspected.
...