Level Check

WARNING: This page is about a different car, the 2009 Nissan Maxima. However, it is still accessible from the selected car via links, so may be relevant.

Make sure that a brake fluid level in reservoir tank is between MAX and MIN lines as shown.
Visually check around reservoir tank for fluid leakage.
If the level is excessively low, check brake system for leaks.
If brake warning lamp remains illuminated after parking brake pedal is released, check brake system for fluid leaks.

Fig 1: Identifying Reservoir Tank MAX And MIN Level

Courtesy of NISSAN MOTOR CO., U.S.A.