ATG 320 - GM Brake Systems

1. Perform proper shop safety procedures.
   1. Apply work area safety skills.
   2. Demonstrate safe personal working habits.
   3. Practice safe tool and equipment usage.
   4. Follow manufacturer and government warnings and regulations and repair procedures.
   5. Acknowledge liability involved with brake repair.
2. Explain principles involved with brake system operation.
   1. Analyze vehicle braking requirements.
   2. Discuss math and science principals involved in stopping a vehicle.
   3. Demonstrate an understanding of friction principles.
   4. Describe hydraulic theory and how it applies to base brake systems.
   5. Describe relationship between atmospheric pressure and vacuum.
3. Examine base brake sub-system.
   1. Discuss master cylinder operation.
   2. Discuss brake booster operation (vacuum and hydraulic).
   3. Discuss drum brake systems design and operation.
   4. Discuss disc brake system design and operation.
   5. Examine brake balance control systems.
   6. Identify components of the brake warning light system.
   7. Discuss the purpose and operation of ABS.
4. Hydraulic System Diagnosis and Repair.
   1. Diagnose pressure concerns in the brake system using hydraulic principles (Pascal?s Law).
   2. Measure brake pedal height, travel, and free play (as applicable); determine necessary action.
   3. Check master cylinder for internal/external leaks and proper operation; determine necessary action.
   4. Remove, bench bleed, and reinstall master cylinder.
   5. Inspect, remove, and install hydraulic brake system components.
   6. Fabricate and install brake lines.
   7. Select, handle, store, and fill brake fluids to proper level.
   8. Bleed and/or flush brake system.
   9. Test brake fluid for contamination; determine necessary action.
5. Drum Brake Diagnosis and Repair.
   1. Diagnose poor stopping, noise, vibration, pulling, grabbing, dragging or pedal pulsation concerns; determine necessary action.
   2. Remove, clean, inspect, and measure brake drum diameter; determine necessary action.
   3. Refinish brake drum and measure final drum diameter; compare with specifications.
   4. Remove, clean, and inspect brake shoes, springs, pins, clips, levers, adjusters/self-adjusters, other related brake hardware, and backing support plates; lubricate and reassemble.
   5. Inspect wheel cylinders for leaks and proper operation; remove and replace as needed.
   6. Pre-adjust brake shoes and parking brake; install brake drums or drum/hub assemblies and wheel bearings; perform final checks and adjustments.
6. Disc Brake Diagnosis and Repair.
   1. Diagnose poor stopping, noise, vibration, pulling, grabbing, dragging, or pulsation concerns; determine necessary action.
   2. Remove and clean caliper assembly; inspect for leaks and damage/wear to caliper housing; determine necessary action.
   3. Clean and inspect caliper mounting and slides/pins for proper operation, wear, and damage; determine necessary action.
   4. Remove, inspect, and replace pads and retaining hardware; determine necessary action.
   5. Lubricate and reinstall caliper, pads, and related hardware; seat pads and inspect for leaks.
   6. Clean and inspect rotor; measure rotor thickness, thickness variation, and lateral runout; determine necessary action.
   7. Remove and reinstall rotor.
   8. Refinish rotor on vehicle; measure final rotor thickness and compare with specifications.
   9. Refinish rotor off vehicle; measure final rotor thickness and compare with specifications.
   10. Retract and re-adjust caliper piston on an integrated parking brake system.
   11. Check brake pad wear indicator; determine necessary action.
   12. Describe importance of operating vehicle to burnish/break-in replacement brake pads according to manufacturer?s recommendations.
7. Power-Assist Units Diagnosis and Repair.
   1. Check vacuum supply (manifold or auxiliary pump) to vacuum-type power booster.
   2. Inspect vacuum-type power booster unit for leaks; inspect the check-valve for proper operation; determine necessary action.
   3. Inspect and test hydraulically-assisted power brake system for leaks and proper operation; determine necessary action.
8. Miscellaneous (Wheel Bearings, Parking Brakes, Electrical, Etc.) Diagnosis and Repair.
   1. Diagnose wheel bearing noises, wheel shimmy, and vibration concerns; determine necessary action.
   2. Remove, clean, inspect, repack, and install wheel bearings; replace seals; install hub and adjust bearings.
   3. Check parking brake cables and components for wear, binding, and corrosion; clean, lubricate, adjust or replace as needed.
   4. Check parking brake operation and parking brake indicator light system operation; determine necessary action.
   5. Check operation of brake stop light system.
   6. Replace wheel bearing and race.
   7. Remove and reinstall sealed wheel bearing assembly.
   8. Inspect and replace wheel studs.
9. Electronic Brake, Traction and Stability Control Systems Diagnosis and Repair.
   1. Identify and inspect electronic brake control system components; determine necessary action.
   2. Identify traction control/vehicle stability control system components.
   3. Diagnose electronic brake control system electronic control(s) and components by retrieving diagnostic trouble codes, and/or using recommended test equipment; determine necessary action.
   4. Bleed the electronic brake control system hydraulic circuits.
   5. Test, diagnose, and service electronic brake control system speed sensors (digital and analog), toothed ring (tone wheel), and circuits using a graphing multi-meter (GMM)/digital storage oscilloscope (DSO) (includes output signal, resistance, shorts to voltage/ground, and frequency data).
   6. Diagnose electronic brake control system braking concerns caused by vehicle modifications (tire size, curb height, final drive ratio, etc.).