ISO 11992-3:2021

Overview

ISO 11992-3:2021 specifies the application layer for digital communication across electrical connections between towing and towed vehicles (vehicles > 3 500 kg). It defines the payload of messages, parameter groups, and message sets for equipment other than brakes and running gear, enabling standardized interchange of data between tractor units, trailers and between towed vehicles. The standard also supports object detection (OD) parameters and identifies OD device installation via a dedicated message. Note: conformance and interoperability test plans are not included in this document.

Keywords: ISO 11992-3:2021, application layer, towing and towed vehicles, vehicle-to-trailer communication, object detection (OD), electrical connections.

Key topics and technical requirements

• Application layer definitions: message payload structure and parameter coding to ensure consistent interpretation across vehicle systems.
• Parameter groups: a wide set of parameters for non-braking equipment, including (examples taken from the document):
  • Rear obstacle distance and object detection device (ODD) messages
  • Thermal body temperature and ambient sensors
  • Lighting controls and state (stop lights, direction indicators, rear/reversing lights, marker lights, convoy/black-out selections)
  • Power take-off (PTO) control and feedback, starter and engine control switches
  • Engine and transmission-related parameters (speed, torque requests, gear state, percent clutch slip)
  • Status and identification parameters (ODM version, identification data index/content, OD status indicator)
• OD support: message sets and parameters for object detection functions and a dedicated message to indicate OD device installation in the towed vehicle.
• Payload semantics: clear definitions for units, value ranges and confidence levels (e.g., velocity/yaw rate confidence) to support interoperable implementations.
• Scope limitations: does not cover brakes/running gear application details and excludes conformance/interoperability test plans.

Practical applications

• Enables reliable vehicle-to-trailer communication for heavy commercial vehicles, trailers, and towed equipment.
• Supports integration of object detection systems on trailers (rear obstacle sensing, ADAS-type features) and exchange of OD status with the towing vehicle.
• Standardizes trailer lighting controls and special modes (convoy, black‑out) across manufacturers.
• Provides common parameter definitions for telematics, fleet management, safety systems, and ECU integration between tractor and trailer.

Who should use this standard

• Automotive OEMs and trailer manufacturers implementing electrical/electronic interfaces.
• ECU and telematics suppliers building towing–towed communication solutions.
• System integrators, vehicle system architects and fleet telematics vendors.
• Regulators and standards committees referencing consistent in‑vehicle data exchange for heavy vehicles.

Related standards

• Other parts of the ISO 11992 series (covering lower layers and complementary message sets) and vehicle electrical interface standards. Use ISO 11992-3 in conjunction with the series’ physical and transport-layer specifications to achieve full end‑to‑end interoperability.