ISO 4009:2026

International
Standard
ISO 4009
Fourth edition
Commercial vehicles — Location
2026-02
of electrical and pneumatic
connections between towing
vehicles and trailers
Véhicules utilitaires — Emplacement des connexions électriques
et pneumatiques entre véhicules tracteurs et véhicules remorqués
Reference number
© ISO 2026
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Published in Switzerland
ii
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Connection locations . 1
5 Connection dimensions . 5
6 Clearance space . 6
7 Flexible pipes of electrical and pneumatic connections. 6
7.1 Locations .6
7.2 Length .6
7.2.1 General requirement . .6
7.2.2 Towing vehicles or trailers with rear-mounted coupling .6
7.2.3 Towing vehicles or trailers with coupling mounted forward and below and
articulated vehicles .6
Annex A (normative) The arrangement of the connectors . 9
Bibliography .11

iii
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out through
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with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
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in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the different types
of ISO documents should be noted. This document was drafted in accordance with the editorial rules of the
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www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 22, Road vehicles, Subcommittee SC 40, Specific
aspects for passenger cars, light and heavy commercial vehicles, special vehicles, buses and trailers/caravans.
This fourth edition of ISO 4009 is a technical revision of ISO 4009:2000, which was withdrawn in 2017.
The main changes are as follows:
— multiple-vehicle combinations have been added to the scope;
— new connectors have been added in Figure 1 to Figure 4;
— the arrangement of the connectors has been changed in Figure 1 to Figure 4;
— general requirement for the length of flexible pipes has been added;
— the arrangement of the connectors has been added in a new Annex A;
— editorial changes have been made.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.

iv
Introduction
Standardization requirements for the arrangement of electrical and pneumatic connections between
towing vehicles and trailers are crucial to ensure seamless connectivity, operational safety, and the
reliable functioning of vehicle combinations. As vehicle technology advances rapidly and an increasing
variety of vehicles enter transportation market, more standardized requirements have been proposed for
the arrangement of these connections. For instance, some vehicles allow the upper and lower mounting
surfaces of connectors to be integrated into a single plane. Unifying the arrangement of connectors for
drawbar-trailers and centre-axle trailers would further improve operational convenience. Some pipelines
are installed at low positions, making them prone to ground contact and abrasion, so adding protective
measures is beneficial for the pipelines. Additionally, incorporating schematic diagrams of connector layouts
in this standard enhances its practicality.
Therefore, further ways to enhance the interchangeability between tractors and trailers, standardize the
arrangement of connections, and ensure the safe operation of vehicle combinations must be explored.

v
International Standard ISO 4009:2026(en)
Commercial vehicles — Location of electrical and pneumatic
connections between towing vehicles and trailers
1 Scope
This document specifies the locations of coupling devices for electrical and pneumatic connections between
towing and towed commercial road vehicles. It is applicable to heavy vehicles equipped with pneumatic
braking systems and 24 V electrical equipment of the following types: drawbar-trailer combinations,
centre-axle trailer combinations and multiple-vehicle combinations whose towing vehicles or trailers have
rear-mounted couplings or couplings mounted forward and below, and articulated vehicles.
This document is not applicable to car carriers, or road vehicles equipped only with fully automatic coupling
system (FACS) according to the ISO 13044 series, not mounted on the front of the trailer.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes
requirements of this document. For dated references, only the edition cited applies. For undated references,
the latest edition of the referenced document (including any amendments) applies.
ISO 1185, Road vehicles — Connectors for the electrical connection of towing and towed vehicles — 7-pole
connector type 24 N (normal) for vehicles with 24 V nominal supply voltage
ISO 1728, Road vehicles — Pneumatic braking connections between motor vehicles and towed vehicles —
Interchangeability
ISO 3731, Road vehicles — Connectors for the electrical connection of towing and towed vehicles — 7-pole
connector type 24 S (supplementary) for vehicles with 24 V nominal supply voltage
ISO 7638-1, Road vehicles — Connectors for the electrical connection of towing and towed vehicles — Part 1:
Connectors for braking systems and running gear of vehicles with 24 V nominal supply voltage
ISO 12098, Road vehicles — Connectors for the electrical connection of towing and towed vehicles — 15-pole
connector for vehicles with 24 V nominal supply voltage
ISO 25981, Road vehicles — Connectors for the electrical connection of towing and towed vehicles — Connectors
for electronically monitored charging systems with 12 V or 24 V nominal supply voltage
3 Terms and definitions
No terms and definitions are listed in this document.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
4 Connection locations
The locations for electrical and pneumatic connections shall be in accordance with Figure 1 and Figure 2
for towing vehicles or trailers with rear-mounted couplings, Figure 3 for towing vehicles or trailers with
couplings mounted forward
...