1991 Ford E-350 Econoline Brake Service (ONLINE REPAIR MANUALS)

MASTER CYLINDER

The master cylinder consists primarily of a hydraulic cylinder, primary and secondary hydraulic pistons and a single or dual chamber fluid reservoir. The front brakes are connected to the primary outlet port(s) and are actuated by the primary piston assembly. The rear brakes are connected to the secondary outlet port and are actuated by the secondary piston assembly.

HYDRAULIC CONTROL VALVES

Combination Valve

This multi-function hydraulic control unit consists primarily of a pressure differential valve, brake lamp warning switch and a proportioning valve. A pressure diff...

SYSTEM COMPONENT LOCATIONS

Refer to system component locations, Figs. through , whenever diagnosis is required. Always disconnect the battery ground cable whenever checking resistance values within the system.

INSTRUMENTATION CHECKS

Brake System (Red) Warning Lamp

To check brake system warning lamp, turn ignition key to the Start position. The red warning lamp should glow momentarily. The warning lamp will also illuminate if the parking brake mechanism is not fully released. If warning lamp fails to glow, service of the electrical system is indicated. If warning lamp illu...

AEROSTAR

• Disconnect brake warning lamp electrical connector from master cylinder.
• Disconnect hydraulic lines from master cylinder, then remove master cylinder to brake booster retaining nuts and the master cylinder.
• Before installing cylinder, check distance from outer end of master cylinder pushrod to front face of booster assembly using suitable gauge block, Fig. . Pushrod length should be .980-.995 inch. Turn pushrod adjusting screw inward or outward until specified length is achieved.
• Reinstall master cylinder and retaining nuts, reconnect hydraulic lines and brake warni...

BRAKE DRUMS

Any time brake drums are removed for brake service, braking surface diameter should be checked with a suitable micrometer at several points to determine if they are within the safe oversize limit stamped on the brake drum outer surface. If braking surface diameter exceeds specifications, the drum must be replaced. If braking surface diameter is within specifications, drums should be cleaned and inspected for cracks, scores, deep grooves, taper, out of round and heat spotting. If drums are cracked or heat spotted, they must be replaced. Minor scores should be remove...

All components are serviced as assemblies and should not be disassembled.

COMPUTER MODULE

1990-91 Models

• Disconnect battery ground cable.
• On all models, disconnect wiring harness from RABS module.
• On Bronco II, Ranger and Explorer models, remove module to instrument panel retaining screws behind center of instrument panel.
• On Aerostar models, remove module to instrument panel anti-skid plate retaining screws on lefthand side of engine cover under instrument panel.
• On E-Series models, remove parking brake actuator assembly as follows:
• Loosen adjusting nut at equalizer.
• From inside e...

Make sure booster rubber reaction disc is properly installed as shown in Fig. , if the master cylinder pushrod is removed or accidentally pulled out. A dislodged disc may cause excessive pedal travel and extreme operation sensitivity. The disc is black compared to the silver colored valve plunger that will be exposed after pushrod and front seal are removed. The booster unit is serviced as an assembly and must be replaced if the reaction disc cannot be properly installed and aligned, or if it cannot be located within the unit itself.

• Disconnect battery ground cable.
• Disconn...