ISO 15031-4:2005

INTERNATIONAL ISO
STANDARD 15031-4
First edition
2005-06-15
Road vehicles — Communication
between vehicle and external equipment
for emissions-related diagnostics —
Part 4:
External test equipment
Véhicules routiers — Communications entre un véhicule et un
équipement externe pour le diagnostic relatif aux émissions —
Partie 4: Équipement d'essai externe

Reference number
©
ISO 2005
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ii © ISO 2005 – All rights reserved

Contents Page
Foreword. v
Introduction . vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions. 2
4 Required functions of the external test equipment. 2
5 Communication protocols . 3
6 Connections to the vehicle . 3
7 Network access. 3
7.1 Automatic determination of communication interface . 3
7.2 Handling of no response from the vehicle. 5
7.3 Handling of multiple responses from the vehicle . 5
7.4 Message structure . 6
7.5 Diagnostic trouble codes monitoring. 6
7.6 Obtain and display OBD emissions-related current data, freeze frame data, and test
parameters and results . 6
7.7 Code clearing . 7
7.8 On-board diagnostic evaluations. 7
7.8.1 Completed on-board system readiness tests. 7
7.8.2 Supported on-board system readiness tests . 7
7.8.3 Malfunction Indicator Lamp — status and control. 7
7.9 Use of StopCommunication service associated with ISO 14230-4 (optional) . 7
8 User interface. 7
8.1 Display . 7
8.2 User input . 8
9 Power requirements . 9
9.1 Vehicle battery voltage support . 9
9.1.1 External test equipment supports only 12 V D.C. vehicle battery voltage . 9
9.1.2 External test equipment supports 12 V D.C. and 24 V D.C. vehicle battery voltage. 9
9.2 Vehicle battery current consumption . 9
10 Electromagnetic compatibility (EMC) . 9
11 Conformance testing. 10
11.1 General. 10
11.2 Determine OBD communication type . 11
11.3 On-board system readiness test . 12
11.4 Select functions . 12
11.5 Select and display items . 12
11.6 Confirm requests to clear codes. 13
11.7 General diagnostic communication tests . 13
11.8 Capacitance and impedance at the diagnostic connector . 14
11.9 Operating voltage and current requirement . 14
11.10 Protocol check . 14
11.11 Alphanumeric display. 14
11.12 User manual and help facility. 14
Annex A (informative) Recommended external test equipment common user interface displays. 16
Annex B (normative) Initialization and identification of ISO 14230-4/ISO 9141-2 protocols. 27
Bibliography . 34

iv © ISO 2005 – All rights reserved

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 ISO
technical committees. Each member body interested in a subject for which a technical committee has been
established has the right to be represented on that committee. International organizations, governmental and
non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the
International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 15031-4 was prepared by Technical Committee ISO/TC 22, Road vehicles, Subcommittee SC 3, Electric
and electronic equipment.
ISO 15031 consists of the following parts, under the general title Road vehicles — Communication between
vehicle and external test equipment for emissions-related diagnostics:
 Part 1: General information
 Part 2: Terms, definitions, abbreviations and acronyms
 Part 3: Diagnostic connector and related electrical circuits, specification and use
 Part 4: External test equipment
 Part 5: Emissions-related diagnostic services
 Part 6: Diagnostic trouble code definitions
 Part 7: Data link security
Introduction
ISO 15031 consists of a number of parts which, taken together, provide a coherent self-consistent set of
specifications to facilitate emissions-related diagnostics. Each part is based on an SAE recommended
practice.
This part of ISO 15031 is based on SAE J1978 FEB98, OBD Scan tool (On-board diagnosis).
ISO 15031 specifies a set of standard diagnostic services to be provided by vehicles (OBD services). This
International Standard specifies a complementary set of facilities, to be provided by external test equipment,
which will include scan tool facilities. These facilities provide complete, efficient and safe access to all of the
public OBD (on-board diagnosis) services on any vehicle, which is compliant with ISO 15031.
Only external test equipment passing the conformance tests specified in ISO 15031-4 may claim or advertise
that it meets or exceeds the requirements of ISO 15031-4.
Partially conforming external test equipment, which does not accommodate all approved protocols is permitted
but shall be so marked.
ISO 15031-4 conformance allows potential purchasers to identify external test equipment which shall work
correctly with a variety of vehicle types and provides assurance for external test equipment users that they
shall not inadvertently cause damage, obtain incorrect results or be unable to access all available OBD
(on-board diagnosis) services. Diagnostic authors who base their test strategies on ISO 15031-4 facilities do
not need to concern themselves with the details of specific types of external test equipment. ISO 15031-4
provides vehicle manufacturers with a level of protection against misdiagnosis or damage to their products
resulting from external test equipment unavailability or inadequacies.
ISO 15031-4 does not preclude the inclusion of additional capabilities or functions in external test equipment.
However, it is the responsibility of the external test equipment designer to ensure that no such capability or
function can adversely affect either an OBD-equipped vehicle, which may be connected to the equipment or
the equipment itself.
ISO 15031-1 provides an introduction to the International Standard.
vi © ISO 2005 – All rights reserved

INTERNATIONAL STANDARD ISO 15031-4:2005(E)

Road vehicles — Communication between vehicle and external
equipment for emissions-related diagnostics —
Part 4:
External test equipment
1 Scope
The document specifies:
 a means of establishing communications between an OBD-equipped vehicle and external test equipment,
 a set of diagnostic services to be provided by the external test equipment in order to exercise the services
defined in ISO 15031-5,
 conformance criteria for the external test equipment.
2 Normative references
The following referenced documents are indispensable for the application 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 7637-2:1990, Road vehicles — Electrical disturbance by conduction and coupling — Part 2: Commercial
vehicles with nominal 24 V supply voltage — Electrical transient conduction along supply lines only
ISO 9141-2: 1994, Road vehicles — Diagnostic systems — Part 2: CARB requirements for interchange of
digital information
ISO 9141-2:1994/Amd.1:1996, Road vehicles — Diagnostic systems — Part 2: CARB requirements for
interchange of digital information — Amendment 1
ISO 11898-1, Road vehicles — Controller area network (CAN) — Part 1: Data link layer and physical
signalling
ISO 11898-2, Road vehicles — Controller area network (CAN) — Part 2: High-speed medium access unit
ISO 14230-4:2000, Road vehicles — Diagnostic systems — Keyword protocol 2000 — Part 4: Requirements
for emission-related systems
ISO TR 15031-2, Road vehicles — Communication between vehicle and external equipment for
...