See answer on "How do you change the front brake pads on a 2001 Ford Focus?" for a description of the location of the resivoir. The answer to this exact location is at the bottom of that answer.
On a 2001 Ford Focus : The brake fluid reservoir is used for the brake and clutch systems
To fill the brake fluid in a 2001 Honda Odyssey, you need to find the brake fluid reservoir and remove the cap. Fill the reservoir with the right amount of fluid and put the cap back on.
The brake and clutch fluid systems are supplied by the brake fluid reservoir ( according to the 2001 Mercury Cougar Owner Guide )
check the brake fluid reservoir and add fluid if necessary.
DOT 3 brake fluid.
IN THE BRAKE MASTER CYLINDER RESERVOIR.
Check the brake fluid level in the reservoir, if it is low you have a leak somewhere.
DOT ( 3 ) or DOT ( 4 ) brake fluid , according to the Owner Guide
Usually it's low brake fluid or a problem with the abs. Check the brake fluid reservoir. Often the brake fluid will go down as the brake pads wear and the calipers has to travel further.
If it only flickers it may be due to low fluid level in the master cylinder. Check your brake fluid reservoir.
Reservoir sits on the master cylinder (actually part of it), Master bolts to the power brake booster
On a 2001 Ford Taurus : You add brake fluid to the brake fluid reservoir , located in the engine compartment , on the drivers side of the engine compartment near the firewall * the firewall is the metal wall that divides the engine compartment from the passenger compartment *