On May 30, 2025, the Ministry of Industry and Information Technology finalized the development of the mandatory national standard GB 21670–2025 – “Technical Requirements and Test Methods for Passenger Car Braking Systems.” The standard was approved and issued by the State Administration for Market Regulation (SAMR) and the Standardization Administration of China (SAC). It will be officially implemented starting January 1, 2026.

Background of the Revision

With the rapid pace of technological iteration in the automotive sector, the structure and functions of passenger car braking systems have undergone significant changes. The previous version, GB 21670–2008, served as a foundational standard in the field of vehicle braking. To accommodate evolving braking technologies and industry needs, the revision aims to update specific indicators and requirements, guiding and regulating the development of braking system products in China.

Revision Timeline

• June 2019: Preliminary research on the standard began

• July 29, 2020: Official project approval

• 2020–2024: Standard revision and test validation phase

• May–July 2024: First public consultation

• September 2024: Draft of Electric Transmission Braking System (ETBS) section

• September–October 2024: Second round of public consultation

• October 2024: Final standard review

• May 30, 2025: Official publication of the standard

Highlights of Revisions

New Additions

• Electric Transmission Braking System (ETBS)

• Requirements covering transmission failure, energy storage devices, warning devices, warning signals, and energy management.

• Regenerative Braking Requirements

• Braking behavior in default operating state

• Operating state after power-on

• Maximum deceleration under default mode

• Functional warning signals for non-default modes

• Emergency Braking Signal Requirements

• Conditions for signal activation and deactivation

• Spare Wheel Braking and Deviation Performance Requirements

• Test condition requirements

• MFDD (Mean Fully  Developed Deceleration) requirements

• Braking distance  standards

• Conditions for performance validation

• Mandatory Installation of Anti-lock Braking System (ABS)

Modifications

• Parking Brake Release
       • Not applicable to remote parking control functions.

• Brake Pad Wear Inspection
       • Wheel removal is not permitted for inspection.
       • Requirements added for assessing disc or drum wear.

• Electronic Parking Brake – Electrical Failure
       • Failure points are clearly defined.

• Electronically Controlled Service Brake Systems
       • Total static braking force after ignition-off is regulated.

• Brake Light Requirements
       • Conditions for brake light activation are specified.
       • Conditions under which the brake light must not activate are clarified.

Key Additions: ETBS-Specific Requirements

Electric Transmission Braking System (ETBS)
A service braking system in which both braking force and transmission are powered solely by an energy storage device under driver control.

Requirements cover:

• Alarm device specifications

• Energy storage device specifications

• Brake warning signal requirements

• Energy management system requirements

Key Additions: Regenerative Braking System Requirements

Applicable to vehicles equipped with Type A or combined Type A and Type B regenerative braking systems.

• In the default operating mode, braking triggered solely by releasing the accelerator must not decelerate the vehicle to a full stop.

• If the system has multiple operating modes, the vehicle must return to the default mode or a driver-predefined mode upon each power-up. The deceleration rate in default mode must not exceed 3 m/s².

• OEMs must explain how to set the operating mode in the user manual or through electronic data records.

• If the regenerative braking system is operating outside the default mode, an optical signal must continuously alert the driver. The signal must remain clearly visible even in daylight.

Test Items

Static Tests

• Documentation inspection

• Component checks: service brake, parking brake, emergency brake systems

• Brake wear and adjustment check

• Structural layout of the braking system

• Bench tests

• Compensator check

• Correlation between control force and pipe pressure (demand vs braking force/deceleration)

• Regenerative braking system check

• Additional checks for trailers with electric braking equipment

• Parking brake function test

• Additional checks for electronically controlled service brake systems

• Fluid reservoir/master cylinder check for hydraulic systems

• Brake fluid marking check

• Signal device checks: warning/self-check, brake light activation, emergency brake signal

• ABS control mode verification

• Energy storage and supply tests (vacuum-assisted, full-power, hydraulic storage, warning thresholds)

• Hydraulic energy capacity checks

• ETBS additional inspections

• Auxiliary equipment inspection

Dynamic Tests

• Unloaded – Basic performance: Type-0 test with power disengaged and engaged

• Unloaded – Failure simulation test

• Unloaded ABS tests:
       • Adhesion utilization on low- and high-friction surfaces
       • Supplementary checks

• Fully Loaded ABS tests:
       • Adhesion utilization (low/high friction)
       • Additional checks
       • Energy consumption test

• Fully Loaded – Basic performance:
       • Type-0 test
       • Parking brake test during motion
       • Response time test
       • Type-I test
       • Comparative Type-0 test
       • Additional tests for Type-B regenerative braking systems
       • Additional tests for electronically controlled service brake systems

• Fully Loaded – Failure simulation test

• Brake signal test

• Emergency brake signal test

• ETBS energy storage test

• ETBS power supply test

• Braking and drift tests for vehicles with temporary spare      wheels/tires

• Braking function safety test

Main Revisions: Test and Performance Requirements

Requirements for Vehicles Equipped with Type A or Type A + B Regenerative Braking Systems:

• Type A Regenerative System – Vehicle State Test Speed:
       The test speed shall be 80% of the vehicle’s maximum design speed and must not exceed 120 km/h.

• Type B Regenerative System – Type-0 Test Charge State Requirement:
       The test must be conducted without using regenerative braking components,      regardless of the battery’s charge status.

• Type B Regenerative System – Recovery Process Test:
       Requirements are added concerning brake pad temperature during the recovery process.

Transmission Gear Requirements for Type-I Test:

• During the heating process, test vehicles equipped with automatic transmissions must remain in “D” gear throughout.

Start Time and Conditions for Hot-State Performance Test:

• The hot-state performance test must begin within 1 minute after the heating process concludes.

Functional Safety Requirements

For Electronically Controlled Brake Systems:

• Clearly defined submission documents and documentation for review

• Specifications for hazard analysis and risk assessment

• Description of safety measures

• Safety analysis requirements

• Vehicle/system-level validation and verification plan and results

Functional Safety Testing of Electronically Controlled Brake Systems:

• Fault types include:
       Sensor faults, communication interface faults, power supply failures

• Functions involved include:
       Electrically controlled service brake, electric transmission service brake, electronically controlled parking brake, Type B and A+B regenerative braking force, Type A and A+B regenerative braking system, anti-lock braking (ABS)

• Vehicle hazards include:
       Unintended deceleration, unintended lateral movement, reduced deceleration capacity, unintended longitudinal movement

Type Approval Equivalence Determination (Same-Type Criteria)

For General Braking Performance:

• Number and layout of axles

• Wheelbase and track width

• Front/rear axle load ratio

• Maximum design speed

• Engine and/or drive motor

• Final drive ratio (drive axle ratio)

• Suspension type

• Tire specifications

• Type of service, emergency, and parking brake systems

• Brake assist method

• Model, manufacturer, and software version of the electronic brake control system

• Brake components: caliper/disc, drum/shoe, brake pads

For Anti-lock Brake System (ABS) Performance:

• Number and layout of axles

• Wheelbase

• Maximum authorized total mass

• Front/rear axle load ratio

• Type of service brake system and brake assist method

• Model, manufacturer, and software version of the electronic brake control system

• Brake components: caliper/disc, drum/shoe, brake pads

For Functional Safety:

• Model, manufacturer, and software version of the electronic brake control system

• Functional safety description of the electronic brake control system

For Temporary Spare Tire Braking Performance:

• Type of temporary spare tire

For Electromagnetic Compatibility:

• Model, manufacturer, and software version of the electronic brake control system

Implementation Timeline

• For new vehicle type approval applications:
       Effective January 1, 2026, except for Clauses 5.2.18 F) and 5.2.19 B), which become effective January 1, 2027

• For vehicles already approved:
       Full compliance required starting January 1, 2027

 Significance of the Standard

• Strengthening safety foundations:
       Further enhances safety requirements for vehicle braking systems.

• Supporting technological development:
       Facilitates the application and development of advanced braking technologies such as brake-by-wire.

• Improving the standardization system:
       Integrates requirements for ABS and other technologies to enhance the integrity of China’s standard framework.

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