Poor Braking

Check for faulty master cylinder. Correct or replace as necessary.
Check for faulty vacuum booster. Correct or replace as necessary.
Check for low level of brake fluid in reservoir. Replenish and bleed as necessary.
Check for air in hydraulic circuit. Bleed as necessary.
Check for faulty disc brake caliper. Clean or replace as necessary.
Check for water or oil on brake pads. Clean or replace as necessary.
Check for poor contact between brake pads and rotor. Correct as necessary.
Check for worn brake pads. Replace as necessary.
Check for rusted brake disc. Grind or replace as necessary.
Check for faulty check valve in vacuum hose. Correct or replace as necessary.