1994 GMC G35/G3500 VAN Brake Service (ONLINE REPAIR MANUALS)

Astro & Safari

For power brake unit replacement procedures, refer to "Delco Moraine Brake Boosters."

Full Size Except C & K Series

Before disconnecting lines from power unit, depress and release brake pedal several times to allow pressure to discharge from accumulator.

• On P30 motor home, raise and support vehicle.
• On all models, remove master cylinder to power brake unit attaching nuts, then position master cylinder aside. Do not disconnect brake lines from master cylinder.
• Disconnect hydraulic lines from power brake unit. Plug all lines and ports to prevent fluid loss and ...

Accessing Diagnostic Trouble Codes

1992

Diagnostic trouble codes can be accessed by connecting a TECH 1 or equivalent scan tool or by manually grounding the Assembly Line Diagnostic Link (ALDL) connector. To manually ground the ALDL connector, connect a jumper wire between terminals A and H, Fig. , and observe the flashes of the brake warning lamp. Note the following when performing the Diagnostic Circuit Check to access diagnostic trouble codes:

• When terminals are jumped, count number of short flashes starting from initial long flash, include long flash in count.
• The count se...

Removal

• Siphon ^2/3 of brake fluid from master cylinder reservoir serving front disc brakes.
• Raise vehicle, support on jack stands and remove front wheels.
• Bottom caliper piston in bore. Insert a screwdriver between inboard shoe and piston, then pry piston back into bore. The piston can also be bottomed in the bore with a large C-clamp, Fig. .
• Remove support key retaining screw.
• Drive caliper support key and spring from steering knuckle with a suitable drift and hammer, Fig. .
• Lift caliper from anchor plate and off rotor, Fig. . Hang caliper from coil spring with wire. Do not allow cal...

When working on or around brake assemblies, care must be taken to prevent breathing asbestos dust, as many manufacturers incorporate asbestos fibers in the production of brake linings. During routine service operations, the amount of asbestos dust from brake lining wear is at a low level due to a chemical breakdown during use, and a few precautions will minimize exposure. Do not sand or grind brake linings unless suitable local exhaust ventilation equipment is used to prevent exces...

4WD Models

• Raise and support vehicle.
• Remove tire and wheel.
• Remove caliper as outlined under "Caliper Service."
• On ^K1500 and ^K2500 models, remove rotor.
• On K3500 models proceed as follows:
• Remove hub retaining nut.
• Remove four hub/rotor retaining bolts on back side of spindle.
• Using suitable wheel puller, remove rotor assembly.
• On K1500 and K2500 models, reverse procedure to install, tightening all bolts to specifications. Install caliper as outlined under "Caliper Service."
• On K3500 models, reverse procedure to install, noting the following:
• Torque hub nut to 173 ft. lbs
• Torque hub and bear...

Disassemble

• Place accumulator compressor tool No. J-26889 or equivalent, around end of accumulator.
• Install nut onto stud as shown in Fig. , then depress the 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.
• Using a suitable saw, cut off eyelet of pedal rod, then remove the boot.
• Remove nut, bracket and bolts, then separate cover from housing.
• Remove piston assembly and seals...