Q: How to remove and install the master cylinder and brake fluid reservoir on Ford Focus?
A: To remove the Brake Master Cylinder, first exhaust the vacuum in the servo by pressing the brake pedal several times with the engine off, then disconnect the negative battery cable. For models from 2005 onward, the battery should be removed. Disconnect the low fluid level warning light multi-plug from the fluid reservoir and unscrew the cap. Draw off the hydraulic fluid using an old battery hydrometer or similar method, or alternatively, raise the vehicle, remove the wheels, loosen the front bleed nipples, and drain the fluid. Lower the vehicle, undo the securing bolts from the air filter housing and intake tube, and remove them. Disconnect the electrical connector from the auxiliary fuse box, remove the retaining screw, and temporarily move the fuse box. Release the clip and disconnect the fluid supply hose from the brake fluid reservoir to the Brake Master Cylinder, keeping the end higher than the reservoir level to prevent fluid loss or dirt entry. Identify the brake pipe locations on the Brake Master Cylinder, noting that non-ABS models have four pipes while ABS models have two. Place rags beneath the Brake Master Cylinder to catch any spilled hydraulic fluid, clean around the hydraulic fitting nuts, and unscrew the nuts to disconnect the hydraulic lines, using a split ring wrench if necessary. Cap the ends of the pipes and Brake Master Cylinder to prevent contamination. For vehicles with TCS, disconnect the pressure sensor's electrical connector, then remove the Brake Master Cylinder securing nuts and withdraw the Brake Master Cylinder from the servo unit, recovering the gasket or seal. If the Brake Master Cylinder is faulty, it must be replaced, as no overhaul kits are available. The brake fluid reservoir is separate from the Brake Master Cylinder; disconnect the electrical connector from the filler cap, unscrew the cap, and empty the brake fluid. Detach the wiring harness from the lower part of the reservoir, remove the two securing screws, and detach it from the firewall. Release the clip and disconnect the fluid supply hoses for the brake and clutch fluid reservoir. For installation, reverse the removal procedure, ensuring to clean the contact surfaces, install a new gasket, tighten the nuts to the specified torque, carefully insert the brake pipes, fill the reservoir with fresh brake fluid, bleed the brake hydraulic system, and test the brakes before returning the vehicle to normal service.