FMVSS 105: Brake Equipment, Stopping Tests, and Penalties

FMVSS 105 is the Federal Motor Vehicle Safety Standard that sets minimum braking performance and equipment requirements for medium and heavy vehicles equipped with hydraulic or electric brake systems. Codified at 49 CFR 571.105 and enforced by the National Highway Traffic Safety Administration, it covers service brakes and parking brakes on multi-purpose passenger vehicles, trucks, and buses with a gross vehicle weight rating above 7,716 pounds (3,500 kilograms).¹ Manufacturers self-certify compliance before a covered vehicle can be sold in the United States.

Which Vehicles Are Covered

The standard applies to multi-purpose passenger vehicles, trucks, and buses over 7,716 pounds GVWR that use hydraulic or electric brake systems. That sweeps in medium-duty pickups, delivery vans, shuttle buses, and school buses.¹

Passenger cars and lighter vehicles at or below the 7,716-pound threshold are governed by FMVSS 135 instead.² Vehicles with air brakes, common on heavy tractor-trailers, are covered by FMVSS 121.³ Motorcycles and trailers are not covered by FMVSS 105.

Required Brake Equipment

Service Brake and Automatic Adjustment

Every covered vehicle needs a service brake system acting on all wheels. Because friction material wears with use, the standard requires an automatic adjustment mechanism that compensates for that wear without any driver intervention.⁴

Brake Fluid Reservoir

Vehicles with a split hydraulic system must have a master cylinder reservoir divided into a separate compartment for each subsystem, so a leak in one circuit does not drain the other. The reservoir has to hold enough fluid to charge the full system and to accommodate the extra volume needed as pads wear to their service limit. A brake fluid warning statement must appear on or near the filler cap, and the fluid must meet FMVSS 116.¹⁵

Brake Warning Lamp

At least one brake warning lamp must be visible to the driver, and it must activate for any of these conditions:

A major drop in hydraulic pressure from a ruptured line or failed circuit.
Brake fluid below the manufacturer’s recommended safe level, or below one-quarter of a reservoir compartment’s capacity, whichever is greater.
A malfunction in the antilock brake system, or a total electrical failure in a variable-proportioning system.
The parking brake being engaged.
For electrically actuated brakes, a power source failure or low battery charge.
For electric vehicles using regenerative braking as part of the service brake, a failure of that system.

Vehicles at or below 10,000 pounds GVWR may use a single common lamp for all of these. Above 10,000 pounds, a single lamp can still combine pressure loss, low fluid, and parking brake application, but ABS malfunctions need a dedicated separate lamp.⁴

Stopping-Distance Tests

The heart of the standard is a series of effectiveness tests at maximum loaded weight, each with maximum stopping distances laid out in the regulation’s Table II. The exact numbers vary by weight class and test condition rather than reducing to one universal figure.

First effectiveness test, before the brakes are burnished: stops from 30 mph and 60 mph within Column I distances.
Second effectiveness test, after burnishing: vehicles at or below 10,000 pounds GVWR and school buses above that weight are tested from both 30 mph and 60 mph against Column II; other vehicles above 10,000 pounds are tested only from 60 mph.
Third effectiveness test at lightly loaded weight, from 60 mph, against Column III.
Fourth effectiveness test for vehicles at or below 10,000 pounds GVWR, from 30 mph and 60 mph, against Column I again.

The layered structure confirms that brakes perform when new, after break-in, at light load, and after use.⁴

Fade and Recovery

Repeated hard braking generates heat that degrades stopping performance, so the standard requires a fade sequence followed by proof of recovery. The procedure differs by weight class.

For vehicles at or below 10,000 pounds GVWR, the sequence runs five successive stops from 60 mph (ten in the second cycle), each holding at least 15 feet per second per second of deceleration. After the fade stops, five more stops are made at the maximum deceleration achievable between 5 and 15 feet per second per second, followed by recovery stops confirming a return to normal braking.¹

For vehicles above 10,000 pounds GVWR, the fade portion uses ten snubs from 40 mph to 20 mph (twenty in the second cycle) at 10 feet per second per second. Snubs slow the vehicle through a speed range rather than to a stop, matching how heavier vehicles manage speed on descents.⁴

Water Recovery

The vehicle drives for two minutes at 5 mph through a trough with six inches of standing water. It then accelerates to 30 mph and makes five recovery stops at 10 feet per second per second each, while the test tracks how much extra pedal force the driver needs compared to a dry-brake baseline.

For the first four stops, pedal force cannot exceed 150 pounds. By the fifth stop, the brakes must have dried enough that pedal force approaches baseline. Vehicles at or below 10,000 pounds GVWR get a fifth-stop allowance of 45 pounds above the baseline average, capped at 90 pounds total. Heavier vehicles are allowed 60 pounds above baseline, capped at 110 pounds.⁶

Partial-Failure Performance

Split System Failure

When a split hydraulic system loses one circuit, the surviving circuit must stop the vehicle from 60 mph within the Column IV distance in Table II. A vehicle that does not use a split system has to achieve that same distance ten consecutive times from 60 mph with the failure present.⁴

Power Assist or Power Unit Failure

If a vacuum or hydraulic power assist fails and its reserve energy is depleted, the driver must still be able to stop the vehicle. Manufacturers may choose among several compliance paths. One option is a single stop from 60 mph within the Column IV distance on muscle force alone. Another, available when a backup system activates automatically on power loss, is 15 consecutive stops from 60 mph averaging at least 12 feet per second per second of deceleration, roughly 323 feet per stop.¹

Electrical Circuit Failure

When the brake signal travels electrically between the pedal and any part of the foundation brakes, a single electrical circuit failure with all other systems intact must still allow a stop from 60 mph within the Column IV distance. The same rule applies to a single failure of a regenerative braking system when regen is part of the service brake.⁶

Electric Vehicles and Regenerative Braking

The standard defines a regenerative braking system as one that uses the propulsion motor to partially brake the vehicle while returning electrical energy to the batteries or dissipating it. When regen is integrated into the service brake, it is treated as a subsystem that can fail on its own: a regen failure by itself cannot push stopping distances past the partial-failure limits, and the warning lamp must specifically alert the driver to a regen failure. Vehicles with electrically actuated foundation brakes face the parallel single-electrical-failure test described above.⁶

Parking Brake

The parking brake must hold the vehicle motionless for five minutes on a grade, in both forward and reverse directions, without exceeding a specified control force. The required grade depends on vehicle type and weight.

Passenger cars and school buses at or below 10,000 pounds GVWR: 30 percent grade.
Other multi-purpose passenger vehicles, trucks, and buses at or below 10,000 pounds GVWR: 20 percent grade.
All multi-purpose passenger vehicles, trucks, and buses (including school buses) above 10,000 pounds GVWR: 20 percent grade.

School buses at or below 10,000 pounds face the steeper grade requirement.¹

How Compliance Works

The United States uses self-certification. NHTSA does not test and approve vehicles before sale. Each manufacturer certifies that its vehicles meet all applicable Federal Motor Vehicle Safety Standards, including FMVSS 105, and carries legal responsibility for that certification. A permanent label near the driver’s door states conformance, the manufacturer’s name, the date of manufacture, the GVWR, and gross axle weight ratings. The law requires manufacturers to exercise “reasonable care” in issuing the certification, and while NHTSA encourages running the exact test procedures in each standard, it does not prescribe how a manufacturer must verify compliance internally.⁷

Noncompliance and Penalties

A manufacturer that discovers a noncompliance must notify NHTSA and all affected owners, purchasers, and dealers, and remedy the problem at no charge.⁸⁹ NHTSA can also order a recall on its own after investigation.

Federal law authorizes civil penalties of up to $21,000 for each violation, with each noncompliant vehicle counting separately. The maximum aggregate penalty for a related series of violations is $105,000,000. These figures are periodically adjusted for inflation, so the effective ceilings in any given year may be higher.¹⁰ For a fleet of thousands, the per-unit exposure adds up quickly, which is why brake noncompliances tend to move fast once identified.

1
eCFR. 49 CFR 571.105 – Standard No. 105; Hydraulic and Electric Brake Systems
2
eCFR. 49 CFR 571.135 – Standard No. 135; Light Vehicle Brake Systems
3
eCFR. 49 CFR 571.121 – Standard No. 121; Air Brake Systems
4
eCFR. 49 CFR 571.105 – Hydraulic and Electric Brake Systems
5
eCFR. 49 CFR 571.116 – Standard No. 116; Motor Vehicle Brake Fluids
6
eCFR. 49 CFR 571.105 – Hydraulic and Electric Brake Systems
7
National Highway Traffic Safety Administration. New Manufacturer’s Handbook
8
Office of the Law Revision Counsel. 49 USC 30118 – Notification of Defects and Noncompliance
9
eCFR. 49 CFR Part 577 – Defect and Noncompliance Notification
10
Office of the Law Revision Counsel. 49 USC 30165 – Civil Penalties