1999 GMC Savana 3500 Brake Service (ONLINE REPAIR MANUALS)

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...

Excessive Pedal Travel

• Worn brake linings.
• Disc pads knock back after cornering or rough road travel.
• Piston and linings not properly seated or positioned.
• Insufficient fluid in system.
• Loose wheel bearing adjustment.
• Damaged or worn caliper piston seal.
• Improper booster pushrod adjustment.
• Pads out of flat more than .005 inch.
• Rear brake automatic adjusters inoperative.
• Improperly ground rear brake shoes.

Brake Roughness Or Chatter; Pedal Pumping

• Excessive lateral runout of rotor.
• Rotor excessively out of parallel.

Excessive Pedal Effort

• Frozen or seized pistons.
• Brake fluid, oil or grease on ...

Master Cylinder

• On models equipped with manual brake system, disconnect master cylinder pushrod from brake pedal.
• On all models, disconnect all wire conne...

Battery Ground Cable

Prior to service disconnect battery ground cable and isolate as required.

Radio Security System

Theftlock

If the Theftlock system is active when battery power is interrupted, the customers security code must be entered to restore proper function of the radio. To unlock a secured radio after power loss, proceed as follows:

• "LOC" appears with ignition in On position.
• Press "NM" and "000" will appear on display.
• Press "NM" again to make last two digits agree with security code.
• Press "HR" to make first 1 or 2 digits agree with security code.
• Press "AM-FM" to select code entered. "SEC" wi...

This system is used on all models except Montana, Silhouette, Tracker, Trans Sport and Venture. On 2000 S & T Series , four door utility vehicles can be equipped with either a 310 or 325 ABS system. Pickups and two-door utility vehicles are equipped with 310 ABS systems. While both systems are functionally the same, the 310 differs in size and appearance from the 325. It is designed to reduce the occurrence of wheel lock-up during severe braking conditions. To accomplish this function, the system regulates hydraulic brake line pressure by using an Electro-Hydraulic Control Unit (EHC...

Brake System Bleed

Gravity and vacuum bleeding procedures are not recommended for use with the anti-lock brake system. The manual bleed procedure is the preferred method, although pressure bleeding is also possible. Do not pump the brake pedal during the bleeding process, as fluid aeration may occur.

Manual Bleed

• Raise and support vehicle, then connect a clear plastic tube to brake bleed screw at righthand rear wheel.
• Place free end of tube in a glass jar partially filled with clean brake fluid. Ensure end of tube remains submerged in fluid and master cylinder reservoir is kept full.
• ...