2008 GMC Acadia 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...

Brake System Bleed

ABS Automated Bleed

The base hydraulic brake system must be bled before performing this automated bleeding procedure.

• Connect a suitable scan tool to Data Link Connector (DLC).
• Start engine and allow engine to idle.
• Follow instructions on scan tool to access automated bleed procedure.
• Apply brake pedal when instructed by scan tool.
• Turn ignition off and remove scan tool from vehicle.
• Fill brake master cylinder reservoir to maximum fill level with brake fluid from a clean, sealed brake fluid container.
• Bleed hydraulic brake system as outlined under "Hydraulic Brake System... "

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 ...

Removal

Front

• Siphon brake fluid out of master cylinder until fluid level is approximately ^1/3 full, this will prevent fluid overflow when caliper piston is pushed back into its bore.
• Raise and support vehicle, then remove wheels.
• Push piston back into its bore using suitable C-clamp, Fig. .
• Remove brake caliper hose bolt, then two metal gaskets from brake caliper bolt.
• Remove two caliper mounting bolts and lift caliper off of rotor.

Rear

• Siphon brake fluid out of master cylinder until fluid level is approximately ^1/3 full, this will prevent fluid overflow when caliper piston is pushed ...

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...

Hybrid Battery Service

Disconnect

Before working on any high voltage system, be sure to wear the following Personal Protection Equipment: Safety glasses with appropriate side shields when within 50 feet of the vehicle, either indoors or outdoors. Certified and up-to-date Class "0" Insulation gloves rated at 1000 volts with leather protectors. Visually and functionally inspect the gloves before use. Wear the Insulation gloves at all times when working with the high voltage battery assembly, whether the system is energized or not. Failure to follow the procedure exactly as written may res...