2003 Chevrolet Express 3500 Brake Service (ONLINE REPAIR MANUALS)

Aztek & Rendezvous

• Remove coolant reservoir, then relieve fuel system pressure as outlined under. "Precautions."
• Remove cruise control cable from module, then disconnect electrical connector from cruise control module.
• Remove cruise control module from bracket, then the front end sheet metal diagonal brace.
• Remove PCM cover from air cleaner housing, then the PCM and set aside.
• Remove air cleaner intake duct, then bolts from air cleaner assembly and housing.
• Remove fuel lines from pipes and vapor line, then disconnect fluid level sensor switch from brake master cylinder.
• Disc...

Disassemble

• Place accumulator compressor tool No. J-26889, or equivalent, around end of accumulator.
• Install nut onto stud as in. Fig. , then depress accumulator with a C-clamp.
• Remove retainer by using a punch.
• Release C-clamp and remove accumulator compressor tool.
• Remove accumulator, O-ring, retainer, plug and spring,. Fig. .
• Remove retainer, output pushrod, baffle, piston return spring and retainer.
• Cut off eyelet of pedal rod, then remove boot.
• Remove nut, bracket and bolts, then separate cover from housing.
• Remove piston assembly and seals.
• Remove spool valve, then the accu...

Certain general service procedures apply, regardless of whether the brakes are vacuum or hydraulically assisted. Only top quality, clean brake fluid should be used. More seals and valves are used with power brake systems than with ordinary brakes, so an inferior brake fluid will do much more damage. For the same reason, ensure all dirt is kept out of the system. Additionally, care must be taken not to mix the fluids of the booster hydraulic system and brake hydraulic system as the fluids are not compatible.

If the power unit fails, the brakes will still operate, as the convention...

General System

• Inspect components for damage or unusual wear. Replace as required.
• Inspect backing plate mounting bolts and ensure they are tight.
• Inspect wheel cylinders. Excessive fluid indicates cup leakage and need for wheel cylinder replacement. Slight amount of fluid is always present and is considered normal, acting as lubricant for cylinder pistons.
• Inspect adjuster screw operation. If satisfactory, lightly lubricate adjusting screw and washer with suitable brake lube. If operation is unsatisfactory, replace.
• Clean rust and dirt from shoe contact surfaces on backing plate using fi...

Astro & Safari

• Apply parking brake.
• Disconnect reservoir and power steering hoses from booster.
• Remove master cylinder to brake booster retaining nuts.
• Position and support master cylinder away from booster.. Do not remove hydraulic lines from master cylinder.
• Remove booster rod from top of brake pedal.
• Remove booster mounting nuts from inside of vehicle.
• Remove booster assembly and gasket.
• Reverse procedure to install, noting the following:
• Torque booster mounting nuts to 27 ft. lbs.
• Torque master cylinder retaining nuts to 27 ft. lbs.
• Torque power steering hoses to booster n...

Slow Brake Pedal Return

• Excessive seal friction in booster.
• Faulty spool action.
• Restriction in return line from booster to pump reservoir.
• Damaged input rod end.

Grabby Brakes Or Booster Chatters/Pedal Vibrates

• Faulty spool action caused by contamination in sys...