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 InspectionClutch Release Cylinder Removal/Installation [C66 M R]
CAUTION:
Do not allow clutch fluid to get on a painted surface. Clutch fluid contains
properties which can dissolve the paint. If clutch fluid gets on a painted surface,
wash it off with water immediately and wipe the area off completely.
1. Remove the front under cover No.2..
...
Master Cylinder
Purpose/Function
With the adoption of the master cylinder having an enlarged diameter (20.64
mm {0.8126 in}), brake pedal operability has been improved.
For vehicles with DSC, the diameter of the pipe between the master cylinder
and the DSC HU/CM has been increased, improving re ...
Washer Nozzle
Purpose
The washer nozzle sprays the washer fluid sent from the washer motor to the
optimum positions on the windshield.
Construction
A ball-shaped spray orifice is set inside the washer nozzle which can be
adjusted up or down.
The washer nozzle is moved u ...