Overview
ISO 11992-2:2023 defines the SAE J1939-based application layer for exchanging digital information on electrical connections between towing and towed road vehicles (vehicles > 3 500 kg). It specifies the message payloads and parameter groups used by electronically controlled braking systems (including ABS and Vehicle Dynamics Control - VDC) and running‑gear equipment so that tractors, trailers and other towed vehicles can interoperate. Note: conformance and interoperability test plans are not part of this document.
Keywords: ISO 11992-2:2023, application layer, SAE J1939, towing and towed vehicles, electronic braking systems, ABS, VDC, running gear, trailer communication
Key topics and technical requirements
- SAE J1939-based application layer: Defines how braking and running‑gear information is formatted and carried over the vehicle network for towing/towed connections.
- Parameter groups and payloads: Detailed APP (application parameter) specifications for identification, braking and running‑gear parameters.
- Braking system parameters: Wheel speeds, brake demand (service/park), brake cylinder pressures, ABS status, retarder control, brake temperatures, tyre pressure, spring brake and pneumatic supply statuses, stop-lamp and warning requests.
- Identification and geometry: Axle/wheel identification, indexed identification data, geometric data indexes and indexed content to map sensors/actuators across vehicles.
- Running‑gear equipment: Driven-axle load, vehicle body level (nominal and relative), level control requests/status, lift-axle positions, steering axle locking, traction help and ride‑height/ramp‑level parameters.
- Inter-vehicle and intra-towed communication: Supports communication between towing and towed vehicles and among towed vehicles in a combination.
- Conventions and terminology: Standardized symbols, definitions and abbreviated terms to ensure consistent implementation.
Practical applications and users
Who benefits:
- Vehicle OEMs and trailer manufacturers implementing electronic braking and running‑gear interfaces
- ECU and telematics suppliers building compliant CAN/J1939 modules for tractor–trailer communications
- Systems integrators and calibration engineers ensuring correct message mapping and parameter interpretation
- Fleet operators and maintenance teams deploying advanced braking and trailer control features
- Regulatory bodies and safety assessors referencing standardized message semantics for heavy vehicles
Practical uses:
- Enabling coordinated ABS/VDC behavior across tractor and trailer
- Sharing wheel-speed, brake-pressure and tyre data for advanced stability and diagnostics
- Remote control of lift axles, ride height and level control between towing and towed units
- Standardized signalling for emergency, warning lights and brake requests across combinations
Related standards
- SAE J1939 (application-layer foundation referenced by ISO 11992-2)
- Other parts of the ISO 11992 series (complementary layers and profiles for towing/towed communication)
For implementers, ISO 11992-2 provides the parameter definitions and message payload structure needed to achieve interoperable braking and running‑gear communication in heavy vehicle combinations.
