Emergency brake light on 2000 Toyota Tundra

The emergency brake light stays on, although the emergency brake is off. s it possible that it could be low on brake fluid? If so, how do you check the brake fluid and if it is low, how do you fill it? Thanks

Asked by for the 2000 Toyota Tundra
Your tundra has a parking brake warning switch available at $29 to $69 depending on single or double cab.