A5 Brakes

  • Hydraulic System Diagnosis and Repair
  • Master Cylinder 
  • Lines and Hoses 
  • Valves and Switches 
  • Bleeding, Flushing, and Leak Testing 
  • Drum Brake Diagnosis and Repair
  • Disc Brake Diagnosis and Repair
  • Power Assist Units Diagnosis and Repair
  • Miscellaneous Systems Diagnosis and Repair
  • Electronic Brake Control Systems—Antilock Brake Systems (ABS), Traction Control Systems TCS), and Electronic Stability Control System (ESC)—Diagnosis and Repair

Brakes

A. Hydraulic System Diagnosis and Repair (12 questions)

1. Master Cylinder (3 questions)

1. Diagnose poor stopping, dragging, high or low pedal, hard or spongy pedal caused by the master cylinder; determine needed repairs.

2. Diagnose problems in the stepbore/quick take-up master cylinder and internal valves (e.g. volume control devices, quick take‑up valve, fast‑fill valve, pressure regulating valve); determine needed repairs.

3. Measure and adjust master cylinder pushrod length.

4. Check master cylinder for failures by depressing brake pedal; determine needed repairs.

5. Diagnose the cause of master cylinder external fluid leakage.

6. Remove and replace master cylinder; bench bleed and test operation and install master cylinder; verify master cylinder function.

2. Lines and Hoses (3 questions)

1. Diagnose poor stopping, pulling, or dragging caused by problems in the lines and hoses; determine needed repairs.

2. Inspect brake lines and fittings for leaks, dents, kinks, rust, cracks, or wear; inspect for loose fittings and supports; determine needed repairs.

3. Inspect flexible brake hoses for leaks, kinks, cracks, bulging, wear, or corrosion; inspect for loose fittings and supports; determine needed repairs.

4. Replace brake lines, hoses, fittings, and supports; fabricate brake lines using proper material and flaring procedures (double flare and ISO types).

5. Inspect brake lines and hoses for proper routing and support.

3. Valves and Switches (3 questions)

1. Diagnose poor stopping, pulling, or dragging caused by problems in the hydraulic system valve(s); determine needed repairs.

2. Inspect, test, and replace metering, proportioning, pressure differential, and combination valves.

3. Inspect, test, replace, and adjust load or height sensing‑type proportioning valve(s).

4. Inspect, test, and replace brake warning light, switch, sensor and circuit.

4. Bleeding, Flushing, and Leak Testing (3 questions)

1. Diagnose poor stopping, pulling, dragging, or incorrect pedal travel caused by problems in the brake fluid; determined needed repairs.

2. Bleed and/or flush hydraulic system using manual, pressure, vacuum, or surge gravity method(s).

3. Pressure test brake hydraulic system.

4. Select, handle, store, and install proper brake fluids (including silicone fluids).

B. Drum Brake Diagnosis and Repair (5 questions)

1. Diagnose poor stopping, pulling, dragging, or incorrect pedal travel caused by drum brake hydraulic problems; determine needed repairs.

2. Diagnose poor stopping, noise, pulling, grabbing, dragging, pedal pulsation, or incorrect pedal travel caused by drum brake mechanical problems; determine needed repairs.

3. Remove, clean, inspect, and measure brake drums; follow manufacturers’ recommendations in determining need to machine or replace.

4. Machine drums according to manufacturers’ procedures and specifications.

5. Using proper safety procedures, remove, clean, and inspect brake shoes/linings, springs, pins, self‑adjusters, levers, clips, brake backing (support) plates and other related brake hardware; determine needed repairs.

6. Lubricate brake shoe support pads on backing (support) plate, self‑ adjuster mechanisms, and other brake hardware.

7. Inspect wheel cylinder(s) for leakage, operation, and mounting; remove and replace wheel cylinder(s).

8. Install brake shoes and related hardware.

9. Pre‑adjust brake shoes and parking brake before installing brake drums or drum/hub assemblies and wheel bearings.

10. Reinstall wheel, torque lug nuts, and make final checks and adjustments.

C. Disc Brake Diagnosis and Repair (10 questions)

1. Diagnose poor stopping, pulling, dragging, or incorrect pedal travel caused by disc brake hydraulic

problems; determine needed repairs.

2. Diagnose poor stopping, noise, pulling, grabbing, dragging, pedal pulsation or incorrect pedal travel caused by disc brake mechanical problems; determine needed repairs.

3. Retract integral parking brake caliper piston(s) according to manufacturers recommendations.

4. Remove caliper assembly from mountings; inspect for leaks and damage to caliper housing.

5. Clean, inspect, and measure caliper mountings and slides/pins for wear and damage.

6. Remove, clean, and inspect pads and retaining hardware; determine needed repairs, adjustments, and replacements.

7. Clean caliper assembly; inspect external parts for wear, rust, scoring, and damage; replace any damaged or worn parts; determine the need to repair or replace caliper assembly.

8. Clean, inspect, and measure rotor with a dial indicator and a micrometer; follow manufacturers’ recommendations in determining the need to index, machine or replace the rotor.

9. Remove and replace rotor.

10. Machine rotor, using on-car or off-car method, according to manufacturers’ procedures and specifications.

11. Install pads, calipers, and related attaching hardware; lubricate components following manufacturers’ procedures and specifications; bleed system.

12. Adjust calipers with integrated parking brakes according to manufacturers’ recommendations.

13. Fill master cylinder to proper level with recommended fluid; inspect caliper for leaks.

14. Reinstall wheel, torque lug nuts, and make final checks and adjustments.

15. Road test vehicle and burnish/break-in pads according to manufacturer’s recommendations

D. Power Assist Units Diagnosis and Repair (4 questions)

1. Test pedal free travel with and without engine running to check power booster operation.

2. Check vacuum supply (manifold or auxiliary pump) to vacuum‑type power booster.

3. Inspect the vacuum‑type power booster unit for vacuum leaks and proper operation; inspect the check valve for proper operation; repair, adjust, or replace parts as necessary.

4. Inspect and test hydro‑boost system and accumulator for leaks and proper operation; repair or replace parts as necessary; refill system.

E. Miscellaneous Systems (Pedal linkage, Wheel Bearings, Parking Brakes, Electrical, etc.) Diagnosis and Repair (7 questions)

1. Diagnose wheel bearing noises, wheel shimmy and vibration problems; determine needed repairs.

2. Remove, clean, inspect, repack wheel bearings, or replace wheel bearings and races; replace seals; replace hub and bearing assemblies; adjust wheel/hub bearings according to manufacturers’ specifications.

3. Check parking brake system; inspect cables and parts for wear, rust, and corrosion; clean or replace parts as necessary; lubricate assembly.

4. Adjust parking brake assembly; check operation.

5. Test the parking brake indicator light, switch and wiring.

6. Test, adjust, repair or replace brake stop light switch, lamps, and related circuits.

7. Inspect and test brake pedal linkage for binding, looseness, and adjustment; determine needed repairs.

F. Electronic Brake Control Systems: Antilock Brake System (ABS), Traction Control System (TCS), and Electronic Stability Control System (ESC) Diagnosis and Repair (7 questions)

1. Follow manufacturers’ service and safety precautions when inspecting, testing and servicing electronic brake control system, hydraulic, electrical, and mechanical components.

2. Diagnose poor stopping, wheel lock up, false activation, pedal feel and travel, pedal pulsation, and noise concerns associated with the electronic brake control system; determine needed repairs.

3. Observe electronic brake control system indicator light(s) at startup and during road test; determine if further diagnosis is needed.

4. Diagnose electronic brake control system, electronic control(s), components, and circuits using on-board diagnosis and/or recommended test equipment; determine needed repairs.

5. Bleed and/or flush the electronic brake control hydraulic system following manufacturers’ procedures.

6. Remove and install electronic brake control system components following manufacturers’ procedures and specifications; observe proper placement of components and routing of wiring harness.

7. Test, diagnose and service electronic brake control system sensors (such as speed, yaw, steering angle, brake pedal position, etc.) and circuits following manufacturers’ recommended procedures (includes output signal, resistance, shorts to voltage/ground, and frequency data.).

8. Diagnose electronic brake control system braking concerns caused by vehicle modifications (wheel/tire size, curb height, final drive ratio, etc.) and other vehicle mechanical and electrical/electronic modifications (communication, security, and radio, etc.).

9. Repair wiring harness and connectors following manufacturers’ procedures.