Michigan SOS mechanic test

Heavy-Duty Brakes & Braking Systems

Heavy-Duty Brakes & Braking Systems is one of the 20 Secretary of State mechanic certification tests. Here's what the test covers, according to the state's published outline.

Topic guide · questions soon

What's on the test

Official topic	Weight
Basic knowledge Anti-lock brakes (ABS) Stability control system Types of brake line flares Hydro-boost systems Hydraulic brake line material Air brake hand valve Drum brake leak diagnosis Master cylinder operation Preset wheel bearing Grease-soaked brake linings	25%
Air brake diagnosis and repair Air brake systems operation Finding air leaks Air pressure diagnosis Air compressor operation Tractor protection valves Dual diaphragm brake chamber operation Pushrod travel Spring brake repairs Air pressures for fail-safe brakes Adjusting cam actuated brakes Brake linkage lubrication Air line material Slack adjuster and pushrod angle “S” cam brake operation Air dryer operation Trailer brakes won’t release	58%
Hydraulic brake diagnosis and repair Hydro-boost systems Swollen master cylinder diaphragm Cause of gear lube inside brake drums Grabbing brakes Causes of a pulsating pedal Brake lining wear diagnosis	17%

Source: SOS Mechanic Testing Categories Overview (PDF). Test format: most SOS mechanic tests have 55 questions, and a few have 65–100 (SOS FAQ). Passing scores vary by test; your result letter shows the passing score and your score.

Practice questions coming soon

The Heavy-Duty Brakes & Braking Systems practice bank is being written to the official outline below. The All-Mechanic pass will include it when it launches.

Banks available now: Engine Repair · Front End, Suspension & Steering · Brakes & Braking Systems · Electrical Systems · Engine Tune-Up & Performance

Test-day facts

Taken on a touch-screen kiosk at any Secretary of State office. Schedule through SOS e-Services.
$18 per test (effective July 1, 2026).
“Quick pass”: the test ends once you reach the minimum passing score.
No reference materials or electronic devices are allowed.
If you don't pass, your result letter breaks down your performance by subcategory.

Source: michigan.gov/sos mechanic testing

Heavy-Duty Brakes & Braking Systems test FAQ

How many questions are on the Michigan Heavy-Duty Brakes & Braking Systems test?

The Secretary of State says most mechanic tests have 55 questions and a few have 65 to 100. The test is “quick pass,” so it ends as soon as you reach the minimum passing score.

What topics are on the Heavy-Duty Brakes & Braking Systems test?

The SOS Mechanic Testing Categories Overview lists: Basic knowledge (25%), Air brake diagnosis and repair (58%), Hydraulic brake diagnosis and repair (17%).

How much does the test cost, and where do I take it?

Each mechanic test costs $18 (effective July 1, 2026). Tests are taken on a touch-screen kiosk at any Secretary of State office; pre-register and schedule through SOS Online Services. Approved automotive schools can also test their students.

Are these the real test questions?

No. MI Trade Prep questions are original practice items written to the official topic outline. They are not actual exam questions, and MI Trade Prep is not affiliated with the Michigan Department of State.

Sources: SOS mechanic testing · SOS mechanics page · SOS mechanic FAQ