2026 GRADED A+ EXAM
2026 SOS Mechanic Certification- Brakes
Exam GRADED A+
Michigan SOS Brakes Certification: Practice Exam
1. A vehicle with rear drum brakes has a low brake pedal. After backing up and
braking firmly several times, the pedal returns to normal height. What does this
indicate?
• A. A leaking master cylinder.
• B. Air in the hydraulic lines.
• C. The self-adjusters were stuck but are now working.
• D. The brake fluid was low.
• Correct Answer: C
• Rationale: Most drum brake self-adjusters operate when the vehicle is driven in
reverse and the brakes are applied. If the shoes were too far from the drum, the
pedal would be low until adjusted.
2. A technician finds that the brake fluid in the reservoir is dark and murky. What
should be the recommended service?
• A. Top off the reservoir.
• B. Replace the master cylinder.
• C. Flush the brake system with new fluid.
• D. Add a cleaning additive.
• Correct Answer: C
• Rationale: Dark fluid indicates moisture contamination and degraded additives.
Flushing prevents internal corrosion of expensive ABS components.
3. Which of the following is the most likely cause of a "brake pedal pulsation"
during light braking?
• A. Worn brake pads.
,2026 GRADED A+ EXAM
• B. Over-tightened wheel bearings.
• C. Excessive lateral rotor runout.
• D. A faulty power booster.
• Correct Answer: C
• Rationale: Runout causes the rotor to wobble, pushing the pads back and forth,
which the driver feels as a pulse in the pedal.
4. When installing a new set of brake pads, why should the technician "burnish"
(bed-in) the brakes?
• A. To harden the rotor steel.
• B. To transfer a thin layer of friction material to the rotor.
• C. To check for leaks.
• D. To ensure the ABS is working.
• Correct Answer: B
• Rationale: Proper burnishing ensures a consistent friction surface, preventing
noise and ensuring maximum stopping power.
5. A technician finds that the left front brake is dragging. When they open the
bleeder screw, a squirt of fluid comes out and the wheel now spins freely. What is
the most likely cause?
• A. A seized caliper piston.
• B. A restricted brake hose.
• C. A faulty master cylinder.
• D. Worn brake pads.
• Correct Answer: B
• Rationale: An internal restriction in the rubber hose acts as a one-way valve,
trapping pressure at the caliper even after the pedal is released.
6. What is the purpose of the "Brake Pressure Differential Switch"?
• A. To balance pressure between front and rear.
,2026 GRADED A+ EXAM
• B. To illuminate the dashboard warning light if a leak occurs in one circuit.
• C. To turn on the ABS pump.
• D. To sense the weight of the vehicle.
• Correct Answer: B
• Rationale: In a dual-circuit system, if one side loses pressure, the switch slides
to the "low" side, completing the ground for the warning light.
7. Which component in a disc brake system is responsible for pulling the piston
back slightly when the brakes are released?
• A. The return spring.
• B. The square-cut O-ring (seal).
• C. The master cylinder spring.
• D. The anti-rattle clip.
• Correct Answer: B
• Rationale: The square-cut seal twists slightly when the piston moves out; when
pressure is released, the seal "un-twists," pulling the piston back.
8. What is the correct way to check the "Minimum Thickness" of a brake rotor?
• A. Use a dial indicator at the edge.
• B. Use a micrometer at the thinnest point of the friction surface.
• C. Measure the diameter with a tape measure.
• D. Visually inspect for rust.
• Correct Answer: B
• Rationale: A micrometer is the only tool accurate enough to measure thickness
in thousandths of an inch.
9. In a "diagonal split" hydraulic system, which wheels are on the same circuit?
• A. Both Fronts / Both Rears.
• B. Left Front and Right Rear / Right Front and Left Rear.
, 2026 GRADED A+ EXAM
• C. Left Front and Left Rear / Right Front and Right Rear.
• D. Only the Fronts.
• Correct Answer: B
• Rationale: Diagonal splitting ensures that if one circuit fails, the vehicle still has
one front and one rear brake for stable stopping.
10. A driver complains that the brake pedal is very hard to push and the engine
"stumbles" or runs poorly when the brakes are applied. What is the cause?
• A. Leaking master cylinder.
• B. Failed vacuum booster diaphragm.
• C. Worn pads.
• D. Faulty ABS sensor.
• Correct Answer: B
• Rationale: A ruptured booster diaphragm creates a massive vacuum leak for the
engine, causing a lean condition and rough idle while losing power assist.
11. Which tool is used to measure "Brake Drum Out-of-Round"?
• A. Outside micrometer.
• B. Brake drum micrometer (inside).
• C. Feeler gauge.
• D. Straight edge.
• Correct Answer: B
• Rationale: A drum micrometer measures the internal diameter at various points
to check for ovality.
12. When using an "on-car" brake lathe, what is the primary advantage?
• . It is faster than a bench lathe.
• B. It compensates for hub runout.
• C. It uses less electricity.
2026 SOS Mechanic Certification- Brakes
Exam GRADED A+
Michigan SOS Brakes Certification: Practice Exam
1. A vehicle with rear drum brakes has a low brake pedal. After backing up and
braking firmly several times, the pedal returns to normal height. What does this
indicate?
• A. A leaking master cylinder.
• B. Air in the hydraulic lines.
• C. The self-adjusters were stuck but are now working.
• D. The brake fluid was low.
• Correct Answer: C
• Rationale: Most drum brake self-adjusters operate when the vehicle is driven in
reverse and the brakes are applied. If the shoes were too far from the drum, the
pedal would be low until adjusted.
2. A technician finds that the brake fluid in the reservoir is dark and murky. What
should be the recommended service?
• A. Top off the reservoir.
• B. Replace the master cylinder.
• C. Flush the brake system with new fluid.
• D. Add a cleaning additive.
• Correct Answer: C
• Rationale: Dark fluid indicates moisture contamination and degraded additives.
Flushing prevents internal corrosion of expensive ABS components.
3. Which of the following is the most likely cause of a "brake pedal pulsation"
during light braking?
• A. Worn brake pads.
,2026 GRADED A+ EXAM
• B. Over-tightened wheel bearings.
• C. Excessive lateral rotor runout.
• D. A faulty power booster.
• Correct Answer: C
• Rationale: Runout causes the rotor to wobble, pushing the pads back and forth,
which the driver feels as a pulse in the pedal.
4. When installing a new set of brake pads, why should the technician "burnish"
(bed-in) the brakes?
• A. To harden the rotor steel.
• B. To transfer a thin layer of friction material to the rotor.
• C. To check for leaks.
• D. To ensure the ABS is working.
• Correct Answer: B
• Rationale: Proper burnishing ensures a consistent friction surface, preventing
noise and ensuring maximum stopping power.
5. A technician finds that the left front brake is dragging. When they open the
bleeder screw, a squirt of fluid comes out and the wheel now spins freely. What is
the most likely cause?
• A. A seized caliper piston.
• B. A restricted brake hose.
• C. A faulty master cylinder.
• D. Worn brake pads.
• Correct Answer: B
• Rationale: An internal restriction in the rubber hose acts as a one-way valve,
trapping pressure at the caliper even after the pedal is released.
6. What is the purpose of the "Brake Pressure Differential Switch"?
• A. To balance pressure between front and rear.
,2026 GRADED A+ EXAM
• B. To illuminate the dashboard warning light if a leak occurs in one circuit.
• C. To turn on the ABS pump.
• D. To sense the weight of the vehicle.
• Correct Answer: B
• Rationale: In a dual-circuit system, if one side loses pressure, the switch slides
to the "low" side, completing the ground for the warning light.
7. Which component in a disc brake system is responsible for pulling the piston
back slightly when the brakes are released?
• A. The return spring.
• B. The square-cut O-ring (seal).
• C. The master cylinder spring.
• D. The anti-rattle clip.
• Correct Answer: B
• Rationale: The square-cut seal twists slightly when the piston moves out; when
pressure is released, the seal "un-twists," pulling the piston back.
8. What is the correct way to check the "Minimum Thickness" of a brake rotor?
• A. Use a dial indicator at the edge.
• B. Use a micrometer at the thinnest point of the friction surface.
• C. Measure the diameter with a tape measure.
• D. Visually inspect for rust.
• Correct Answer: B
• Rationale: A micrometer is the only tool accurate enough to measure thickness
in thousandths of an inch.
9. In a "diagonal split" hydraulic system, which wheels are on the same circuit?
• A. Both Fronts / Both Rears.
• B. Left Front and Right Rear / Right Front and Left Rear.
, 2026 GRADED A+ EXAM
• C. Left Front and Left Rear / Right Front and Right Rear.
• D. Only the Fronts.
• Correct Answer: B
• Rationale: Diagonal splitting ensures that if one circuit fails, the vehicle still has
one front and one rear brake for stable stopping.
10. A driver complains that the brake pedal is very hard to push and the engine
"stumbles" or runs poorly when the brakes are applied. What is the cause?
• A. Leaking master cylinder.
• B. Failed vacuum booster diaphragm.
• C. Worn pads.
• D. Faulty ABS sensor.
• Correct Answer: B
• Rationale: A ruptured booster diaphragm creates a massive vacuum leak for the
engine, causing a lean condition and rough idle while losing power assist.
11. Which tool is used to measure "Brake Drum Out-of-Round"?
• A. Outside micrometer.
• B. Brake drum micrometer (inside).
• C. Feeler gauge.
• D. Straight edge.
• Correct Answer: B
• Rationale: A drum micrometer measures the internal diameter at various points
to check for ovality.
12. When using an "on-car" brake lathe, what is the primary advantage?
• . It is faster than a bench lathe.
• B. It compensates for hub runout.
• C. It uses less electricity.
