ISO 11992-4-2023 PDF

Full title and description

Road vehicles — Interchange of digital information on electrical connections between towing and towed vehicles — Part 4: Diagnostic communication. This part of ISO 11992 defines diagnostic application requirements and OSI-layer related communication profiles for diagnostic data exchange between a towing vehicle (tractor) and one or more towed vehicles (trailers) for commercial vehicles above 3 500 kg maximum authorized mass.

Abstract

Specifies diagnostic application requirements and OSI-layer communication profiles to support exchange of diagnostic information between towing and towed vehicles on ISO 11992 networks. The document defines how unified diagnostic services (UDS) and relevant transport/profile constraints are applied in the towing–towed vehicle environment; conformance and interoperability test plans are explicitly not part of the standard.

General information

• Status: Published.
• Publication date: April 2023 (published 14 April 2023 in published listings).
• Publisher: International Organization for Standardization (ISO).
• ICS / categories: 43.040.15 (Car informatics; on-board computer systems).
• Edition / version: Edition 3 (2023).
• Number of pages: 30.

Key bibliographic and life‑cycle metadata (status, edition, page count) are recorded on the ISO bibliographic entry for ISO 11992‑4:2023.

Scope

This part applies to diagnostic communication between a towing vehicle and its towed vehicle(s) where the combination has a maximum authorised total mass greater than 3 500 kg. It defines the diagnostic application-layer requirements, message/profile constraints and OSI-layer related profiles required to implement diagnostic services across the towing–towed electrical connection (CAN-based). It is specific to diagnostic exchanges and does not cover non‑diagnostic message uses or conformance test plans.

Key topics and requirements

• Definition of diagnostic application requirements and OSI-layer communication profiles for towing–towed CAN networks.
• Specification of how unified diagnostic services (UDS, ISO 14229) map and are constrained for use over ISO 11992 networks (diagnostic services, sessions, security, response/timeout handling).
• Transport and addressing restrictions and extensions specific to the tractor–trailer CAN identifier structure (29‑bit identifiers used in ISO 11992).
• Application-layer message formats, service timing and error/exception handling rules appropriate to towing/towed topologies and gateways.
• Clarification that conformance and interoperability test plans are excluded from the text (not normative in this part).

Typical use and users

Used by OEM engineering teams (truck and trailer manufacturers), ECU and telematics suppliers, diagnostic tool and test‑equipment vendors, systems integrators, and test laboratories that implement or verify diagnostic functionality across tractor–trailer electrical/CAN interfaces. It is referenced in product specifications, diagnostic stack implementations and gateway designs for commercial vehicles.

Related standards

ISO 11992‑4 is part of the ISO 11992 series and works together with other parts in the series (notably Part 1: physical and data‑link layer, Part 2: application layer for brakes and running gear, and Part 3: application layer for equipment other than brakes and running gear). It also references and constrains the application of vehicle diagnostic standards such as ISO 14229 (UDS) and ISO 15765 (diagnostics on CAN / transport). Relevant related items include ISO 11992‑1:2019, ISO 11992‑2:2023 and ISO 11992‑3:2021.

Keywords

ISO 11992, diagnostic communication, UDS, CAN, trailer, towing vehicle, tractor–trailer, vehicle diagnostics, ISO 14229, ISO 15765, automotive diagnostic services, trailer ECU, gateway, 29‑bit CAN identifier.

FAQ

Q: What is this standard?

A: ISO 11992‑4:2023 is the Part 4 document of the ISO 11992 series that specifies diagnostic communication requirements and OSI‑layer profiles for digital information interchange between towing and towed vehicles (tractor–trailer interfaces) for vehicles over 3 500 kg.

Q: What does it cover?

A: It covers diagnostic application‑layer requirements, how UDS (ISO 14229) is applied and constrained on the towing–towed CAN interface, addressing/transport considerations, timing and error handling, and other OSI‑layer related profiles needed to perform diagnostics across the trailer connection. It does not include formal conformance or interoperability test plans.

Q: Who typically uses it?

A: Truck and trailer OEMs, ECU suppliers, diagnostic tool vendors, systems integrators, and test laboratories use it to design and verify diagnostic capabilities and gateway behavior between tractors and trailers.

Q: Is it current or superseded?

A: ISO 11992‑4:2023 is the current published edition (Edition 3, published April 2023). It replaces and withdraws earlier editions (for example the 2014 edition was withdrawn and superseded by the 2023 edition).

Q: Is it part of a series?

A: Yes — ISO 11992 is a multi‑part series that includes at least Part 1 (physical and data‑link layers), Part 2 (application layer for brakes and running gear), Part 3 (application layer for other equipment) and Part 4 (diagnostic communication). Implementers typically use multiple parts together.

Q: What are the key keywords?

A: Diagnostic communication, UDS, trailer diagnostics, tractor–trailer CAN, ISO 11992, diagnostic services, CAN transport, gateway, trailer ECU.