2003 GMC Sierra 1500 HD Brake Service (ONLINE REPAIR MANUALS)

Manual Bleed

• If vehicle is equipped with power brakes, remove vacuum reserve by applying brakes several times with engine off.
• Fill master cylinder reservoirs with suitable brake fluid.. Ensure to always keep master cylinder reservoirs at least half full during entire bleeding procedure.
• If master cylinder is suspected to have air in the bore, it must be bled first. To bleed master cylinder, proceed as follows:
• Disconnect forward brake pipe connection at master cylinder.
• Allow brake fluid to fill master cylinder bore until it begins to flow from forward pipe connector port.
• Connect...

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...

Service Brake

These brakes have self-adjusting shoe mechanisms that ensure correct lining-to-drum clearances at all times. The automatic adjusters operate only when the brakes are applied as the vehicle is moving rearward or when the vehicle comes to an uphill stop.

Although the brakes are self-adjusting, an initial adjustment is required after the brake shoes have been relined or replaced, or when the length of the adjusting screw has been changed during some other service operation.

Frequent usage of an automatic transmission forward range to halt reverse vehicle motion may prevent t...

The caliper mounts in a way that allows the caliper to move laterally inboard as the brake pads wear. The caliper housing is a one piece casting with the inboard side containing the piston bore. The piston seal also acts as a return mechanism for the piston.

Applying the brake pedal causes the hydraulic pressure that moves the caliper piston. The piston then forces the inboard brake pad against the inboard braking surface of the rotor. Increasing the force against...

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, on models with hydraulic assist brakes, 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 brak...