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 InspectionFilament Inspection
1. Switch the ignition ON (engine off).
2. Turn the rear window defroster switch on.
CAUTION:
Directly touching the rear window defroster filament with the lead of the
tester could damage it. Wrap aluminum foil around the end of the lead and inspect
the filament by touching it ...
Add-On Non-Genuine Parts and Accessories
Non-genuine parts and accessories for Mazda vehicles can be found in stores.
These may fit your vehicle, but they are not approved by Mazda for use with Mazda
vehicles. When you install non-genuine parts or accessories, they could affect your
vehicle's performance or safety systems; the Maz ...
Pressure Sensor Removal/Installation [Two Step Deployment Control System]
WARNING:
Handling the pressure 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 pressure sensor..
1. Switch the ignition to off.
2. Disconnect the ne ...