ISO 15031-4:2014
(Main)Road vehicles — Communication between vehicle and external equipment for emissions-related diagnostics — Part 4: External test equipment
Road vehicles — Communication between vehicle and external equipment for emissions-related diagnostics — Part 4: External test equipment
ISO 15031-4:2014 specifies a set of standard diagnostic services to be provided by vehicles (OBD services). ISO 15031-4:2014 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 15031-4:2014. ISO 15031-4:2014 specifies - a means of establishing communications between an OBD-equipped vehicle and external test equipment, and - a set of diagnostic services to be provided by the external test equipment in order to exercise the services defined in ISO 15031‑5. ISO 15031-4:2014 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 external test equipment or the external test equipment itself.
Véhicules routiers — Communications entre un véhicule et un équipement externe pour le diagnostic relatif aux émissions — Partie 4: Équipement d'essai externe
General Information
Relations
Standards Content (Sample)
INTERNATIONAL ISO
STANDARD 15031-4
Second edition
2014-02-15
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 2014
© ISO 2014
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form
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ii © ISO 2014 – All rights reserved
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms, definitions, symbols, and abbreviated terms . 2
3.1 Terms and definitions . 2
3.2 Abbreviated terms . 2
3.3 Symbols . 3
4 Conventions . 3
5 Document overview. 3
6 Required functions of the external test equipment . 5
7 Communication protocols . 5
8 Connections to the vehicle . 5
9 Network access . 6
9.1 Automatic determination of communication interface. 6
9.2 Multiple tester communication . 7
9.3 Handling of no response from the vehicle . 8
9.4 Handling of multiple responses from the vehicle . 8
9.5 Message structure . 9
9.6 Diagnostic trouble codes monitoring . 9
9.7 Obtaining and displaying OBD emissions-related current data, freeze frame data, and test
parameters and results . 9
9.8 Code clearing .10
9.9 On-board diagnostic evaluations.10
9.10 Use of StopCommunication service associated with ISO 14230-4 (optional).10
10 User interface .10
10.1 Display .10
10.2 User input .11
11 Power requirements .11
11.1 Vehicle battery voltage support .11
11.2 Vehicle battery current consumption .12
12 Electromagnetic compatibility (EMC) .12
13 Conformance testing .12
Annex A (informative) Recommended external test equipment common user interface displays .13
Annex B (normative) Initialization and identification of ISO 14230‑4/ISO 9141‑2 protocols .26
Bibliography .31
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.
The procedures used to develop this document and those intended for its further maintenance are
described 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 ISO/IEC Directives, Part 2. www.iso.org/directives
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. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received. www.iso.org/patents
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
The committee responsible for this document is ISO/TC 22, Road vehicles, Subcommittee SC 3, Electric
and electronic equipment.
This second edition cancels and replaces the first edition (ISO 15031-4:2005), which has been technically
revised.
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 and use case definition
— Part 2: Guidance on 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
iv © ISO 2014 – All rights reserved
Introduction
0.1 Overview
This International Standard consists of a number of parts which, taken together, provide a coherent
self-consistent set of specifications to facilitate emissions-related diagnostics. ISO 15031-1 provides an
introduction to the series of International Standards. ISO 15031-2 to ISO 15031-7 are based on Society
of Automative Engineers (SAE) recommended practices. This part of ISO 15031 is based on SAE J1978.
This International Standard includes the communication between the vehicle’s On-Board Diagnostics
(OBD) systems and test equipment implemented across vehicles within the scope of the legislated
emissions-related OBD.
To achieve this, it is based on the Open Systems Interconnection (OSI) Basic Reference Model in
accordance with ISO/IEC 7498-1 and ISO/IEC 10731, which structures communication systems into
seven layers. When mapped on this model, the services specified by this International Standard are
broken into the following:
— Diagnostic services (layer 7), specified in:
— ISO 15031-5 (emissions-related OBD);
— Presentation layer (layer 6), specified in:
[4]
— ISO 15031-2, SAE J1930-DA;
[8]
— ISO 15031-5, SAE J1979-DA;
[10]
— ISO 15031-6, SAE J2012-DA (OBD);
— Session layer services (layer 5), specified in:
— ISO 14229-2 supports ISO 15765-4 DoCAN and ISO 14230-4 DoK-Line protocols;
— ISO 14229-2 is not applicable to the SAE J1850 and ISO 9141-2 protocols;
— Transport layer services (layer 4), specified in:
— DoCAN: ISO 15765-2 Transport protocol and network layer services;
— SAE J1850: ISO 15031-5 Emissions-related diagnostic services;
— ISO 9141-2: ISO 15031-5 Emissions-related diagnostic services;
— DoK-Line: ISO 14230-4, ISO 15031-5 Emissions-related diagnostic services;
— Network layer services (layer 3), specified in:
— DoCAN: ISO 15765-2 Transport protocol and network layer services;
— SAE J1850: ISO 15031-5 Emissions-related diagnostic services;
— ISO 9141-2: ISO 15031-5 Emissions-related diagnostic services;
— DoK-Line: ISO 14230-4, ISO 15031-5 Emissions-related diagnostic services;
— Data link layer (layer 2), specified in:
— DoCAN: ISO 15765-4;
— CAN: ISO 11898-1, ISO 11898-2;
— SAE J1850;
— ISO 9141-2;
— DoK-Line: ISO 14230-2;
— Physical layer (layer 1), specified in:
— DoCAN: ISO 15765-4;
— CAN: ISO 11898-1, ISO 11898-2;
— SAE J1850;
— ISO 9141-2;
— DoK-Line: ISO 14230-1;
in accordance with Table 1.
Table 1 — Legislated emissions‑related OBD diagnostic specifications applicable to the OSI
layers
Applicability OSI seven layers Emissions-related OBD communication requirements
Application (layer 7) ISO 15031-5
ISO 15031-2, SAE J1930-DA
Presentation (layer 6) ISO 15031-5, SAE J1979-DA
ISO 15031-6, SAE J2012-DA (OBD)
Seven layers
according to ISO/
Session (layer 5) ISO 14229-2 Not applicable ISO 14229-2
IEC 7498-1 and
ISO/IEC 10731
Transport (layer 4)
ISO 15765-2 ISO 15031-5
Network (layer 3)
ISO 15765-4 ISO 14230-4
Data link (layer 2) ISO 14230-2
ISO 11898-1,
SAE J1850 ISO 9141-2
ISO 11898-2
Physical (layer 1) ISO 14230-1
0.2 SAE document reference concept
This International Standard references several SAE documents which contain all terms, data, and DTC
definitions.
See Figure 1 with the following definition of content in ISO 15031-2, ISO 15031-5, and ISO 15031-6:
— SAE J1930: 15031-2 is concerned with a procedure for naming objects and systems and with the set
of words from which names are built. It references SAE J1930-DA which contains all standardized
naming objects, terms, and abbreviations.
— SAE J1979: 15031-5 is concerned with the definition of emissions-related diagnostic services
(diagnostic test modes). It references SAE J1979-DA which contains all standardized data items like
PIDs, TIDs, OBDMIDs, and ITIDs.
— SAE J2012: 15031-6 is concerned with the procedure for defining emissions-related diagnostic
trouble codes. It references SAE J2012-DA which contains all standardized data items like DTCs and
FTBs.
vi © ISO 2014 – All rights reserved
ISO 15031-4
Emissions OBD
External test equipment
SAE J2012-DA
SAE J 1979-DA SAE J1930-DA
emissions-related
emissions-related emissions-related
diagnostic trouble
data deinition acronym deinition
code deinition
SAE Digital Annex – emissions-related data deinition
Figure 1 — SAE Digital Annex document reference
OBD regulations require passenger cars and light, medium, and heavy duty trucks to support a minimum
set of diagnostic information to external (off-board) “generic” test equipment.
0.3 SAE Digital Annex revision procedure
New emissions-related regulatory requirements drive new in-vehicle technology to lower emissions.
New technology related OBD monitor data and diagnostic trouble codes need to be standardized to
support the external (off-board) “generic” test equipment. All relevant information is proposed by the
automotive industry represented by members of the appropriate SAE task force.
ISO 15031-2, ISO 15031−5, and ISO 15031−6 reference a “Change Request Form” to be used for new
data items to be defined by the SAE task force for standardization. The standardized data items will be
[4] [8] [10]
defined in the SAE J1930-DA, SAE J1979-DA, and SAE J2012-DA. Once the information has been
balloted and approved, the documents will be published on the SAE Store website.
The revision request forms and instructions for updating the Registers to ISO 15031-2, ISO 15031-5, and
ISO 15031-6 can be obtained from the Registration Authority’s website.
— For ISO 15031-2: http://www.sae.org/servlets/works/committeeHome.do?comtID=TEVDS7
The column titled “Resources” shows a document with the title: J1930-DA_Revision_Request_Form.
doc. Double click on the name and you will be asked to download the document with the filename
“SAE_J1930-DA_Revision_Request_Form.doc”
— For ISO 15031-5: http://www.sae.org/servlets/works/committeeHome.do?comtID=TEVDS14
The column titled “Resources” shows a document with the title: J1979-DA_Revision_Request_Form.
doc. Double click on the name and you will be asked to download the document with the filename
“SAE_J1979-DA_Revision_Request_Form.doc”
— For ISO 15031-6: http://www.sae.org/servlets/works/committeeHome.do?comtID=TEVDS9
The column titled “Resources” shows a document with the title: J2012-DA_Revision_Request_Form.
doc. Double click on the name and you will be asked to download the document with the filename
“SAE_J2012-DA_Revision_Request_Form.doc”
Fill out the revision request form with your request.
INTERNATIONAL STANDARD ISO 15031-4:2014(E)
Road vehicles — Communication between vehicle and
external equipment for emissions-related diagnostics —
Part 4:
External test equipment
1 Scope
This part of ISO 15031 specifies a set of standard diagnostic services to be provided by vehicles (OBD
services). This part of ISO 15031 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
this part of ISO 15031.
This part of ISO 15031 specifies
— a means of establishing communications between an OBD-equipped vehicle and external test
equipment, and
— a set of diagnostic services to be provided by the external test equipment in order to exercise the
services defined in ISO 15031-5.
This part of ISO 15031 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 external test equipment or the external test equipment itself.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated
references, the latest edition of the referenced document (including any amendments) applies.
ISO 7637-2:2011, Road vehicles — Electrical disturbances from conduction and coupling — Part 2: 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 14230-2:2013, Road vehicles — Diagnostic communication over K-Line (DoK-Line) — Part 2: Data link
layer
ISO 14230-4:2000, Road vehicles — Diagnostic systems — Keyword Protocol 2000 — Part 4: Requirements
for emission-related systems
ISO 15031-2, Road vehicles — Communication between vehicle and external equipment for emissions-related
diagnostics — Part 2: Guidance on terms, definitions, abbreviations and acronyms
ISO 15031-3, Road vehicles — Communication between vehicle and external equipment for emissions-related
diagnostics — Part 3: Diagnostic connector and related electrical circuits, specification and use
ISO 15031-5, Road vehicles — Communication between vehicle and external equipment for emissions-related
diagnostics — Part 5: Emissions-related diagnostic services
ISO 15031-6, Road vehicles — Communication between vehicle and external equipment for emissions-
related diagnostics — Part 6: Diagnostic trouble code definitions
ISO 15765-4, Road vehicles — Diagnostic communication over Controller Area Network (DoCAN) — Part 4:
Requirements for emissions-related systems
ISO 16750-2, Road vehicles — Environmental conditions and testing for electrical and electronic
equipment — Part 2: Electrical loads
SAE J1699-2, Test Cases for OBD-II Scan Tools and I/M Test Equipment
SAE J1850:MAY2001, Class B Data Communications Network Interface
3 Terms, definitions, symbols, and abbreviated terms
3.1 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 15031 (all parts) apply.
3.2 Abbreviated terms
Addr address
DoCAN diagnostic communication over Controller Area Networks
DoK-Line diagnostic communication over K-Line
DTC diagnostic trouble code
ECU electronic control unit
IPT in-use performance tracking
ITID infotype identifier
MIL malfunction indicator lamp
NRC negative response code
OBDMID on-board monitor identifier
OBD on-board diagnostics
PID parameter identifier
PWM pulse width modulated
RPM rounds per minute
TID test identifier
VPM variable pulse width
2 © ISO 2014 – All rights reserved
3.3 Symbols
% percentage
A ampere
°C degree Celsius
Kbps kilobits per second
km/h kilometre per hour
kPa kilopascal
mA milliampere
ms milliseconds
−1
min 1/minute
V voltage
4 Conventions
This International Standard is based on the conventions discussed in the OSI Service Conventions
(ISO/IEC 10731:1994) as they apply for diagnostic services.
5 Document overview
Figure 2 depicts the emissions-related OBD on ISO 15765-4, SAE J1850, ISO 9141-2, and ISO 14230-4
document references according to the OSI model.
The protocol initialization identifies whether ISO 15765-4 DoCAN, SAE J1850, ISO 14230-4 DoK-Line,
or ISO 9141-2 is the data link layer supported by the vehicle. This International Standard references the
standards as an applicable data link for emissions-related OBD.
ISO 15031-5 specifies the applicable emissions-related diagnostic services. This part of ISO 15031
[4] [8]
specifies the data record structures and references SAE J1930-DA, SAE J1979-DA, and SAE J2012-
[10]
DA.
Emissions-related diagnostic services
ISO 15031-1
Emissions OBD
General information and
use case de•inition
SAE J1930-DA
Terms, .
ISO 15031-5
Emissions-related
OSI Layer 7
diagnostic services
SAE J1979-DA
Application
PIDs , MIDs , RIDs ,
InfoTypes
ISO 15031-2, -5, -6
SAE J2012-DA
1 : 1
Emissions-related
OSI Layer 6
DTCs
Terms, Data , DTCs
Presentation
ISO 14229-2 ISO 14229-2
Not Applicable
UDS UDS
OSI Layer 5
(no document available)
Session layer services Part 2: Session layer services
Session
Standardized Service Primitive Interface Not Applicable Standardized Service Primitive Interface
ISO 15765-4 SAE ISO ISO 14230-4
J1850 9141-2
ISO 15031-5
OSI Layer 4
ISO 15765-2
Transport Emissions OBD
DoCAN
Transport
Emissions-related diagnostic services
and
Network
layer services
OSI Layer 3
ISO 14230-4
ISO 15765-4
Network
DoCAN DoK-Line
Part 4:
Requirements Requirements for
for emissions- emissions-
ISO 11898-1 CAN
ISO 14230-2
related systems related systems
Data link layer DoK-Line
ISO 9141-2
OSI Layer 2
SAE J1850
and physical
Data Link
signalling
Data link layer
Part 2:
Class B
CARB
Data
requirements
Communi-
for
cations
ISO 11898 CAN interchange ISO 14230-1
Network
Part 2: High - of digital
DoK-Line
Interface
OSI Layer 1
speed medium information
Physical
access unit Physical layer
Figure 2 — Emissions-related OBD on ISO 15765-4, SAE J1850, ISO 9141-2, and ISO 14230-4
document references according to the OSI model
4 © ISO 2014 – All rights reserved
6 Required functions of the external test equipment
The following are the basic functions that the external test equipment is required to support or provide:
— automatic hands-off determination of the communication interface used to provide OBD services on
the vehicle;
— obtaining and displaying the status and results of vehicle on-board diagnostic evaluations;
— obtaining and displaying OBD emissions-related diagnostic trouble codes (DTCs);
— obtaining and displaying OBD emissions-related current data;
— obtaining and displaying OBD emissions-related freeze frame data;
— clearing the storage of OBD emissions-related DTCs, freeze frame data storage, and diagnostic tests
status;
— obtaining and displaying OBD emissions-related test parameters and results as described in
ISO 15031-5;
— user manual and/or help facility.
7 Communication protocols
The following communication protocols shall be supported:
a) ISO 9141-2: The following specifications clarify and, if in conflict with ISO 9141-2, override any
related specifications in ISO 9141-2:
1) maximum sink current to be supported by the external test equipment is 100 mA;
2) range for all tests performed relative to ISO 7637-2 is −1,0 V to +40,0 V;
3) minimum bus idle period before the external test equipment shall transmit an address and shall
be 300 ms;
b) SAE J1850 41,6 kbps pulse width modulated (PWM);
c) SAE J1850 10,4 kbps variable pulse width (VPW);
d) ISO 14230-4;
e) ISO 15765-4.
A fully compliant external test equipment shall support all communication protocols as specified in
Clause 7.
Only one protocol is allowed to be used in any one vehicle to access all legislated emissions-related
functions. The external test equipment is not required to support simultaneous use of different protocols.
8 Connections to the vehicle
To connect the external test equipment to the vehicle, the ISO 15031-3/SAE J1962 connector shall be
used.
9 Network access
9.1 Automatic determination of communication interface
The external test equipment shall have an “automatic hands-off determination of the communication
interface” built in to determine the communication protocol used in a given vehicle.
Prior to connecting the external test equipment to the vehicle’s diagnostic connector, the ignition key of
the vehicle shall be turned to position “ON”.
The tests to determine the communication interface and protocol may be performed in any order. The
following specified sequence for each test shall be used to determine the interface to be used to access
OBD services on a vehicle.
a) The electrical interface in the external test equipment for the manufacturer discretionary contact
assignments shall be effectively open circuit as a default condition or state while this procedure is
being performed.
b) The equipment shall inform the user that initialization is occurring.
c) The equipment shall, using only the following tests, attempt to determine the OBD communications
protocol used by the vehicle. No user intervention is allowed during this stage. The test equipment
shall not cause bus failures such as CAN bus off.
1) Test for SAE J1850 41,6 kbps PWM
i) Enable the SAE J1850 41,6 kbps PWM interface.
ii) Send a service 0x01 PID 0x00 request message.
iii) If a service 0x01 PID 0x00 response message is received, then SAE J1850 41,6 kbps PWM is
the vehicle’s OBD protocol.
2) Test for SAE J1850 10,4 kbps VPW
i) Enable the SAE J1850 10,4 kbps VPW interface.
ii) Send a service 0x01 PID 0x00 request message.
iii) If a service 0x01 PID 0x00 response message is received, then SAE J1850 10,4 kbps VPW is
the vehicle’s OBD protocol.
3) Test for ISO 14230-4 (fast initialization)
i) Enable the ISO 14230-4 interface (refer to B.2 for information on how to perform the fast
initialization of the ISO 14230-4:2000 protocol).
ii) If the initialization sequence is completed successfully, then ISO 14230-4 is the vehicle’s
OBD protocol.
4) Test for ISO 14230-4/ISO 9141-2 (5 baud initialization)
i) Enable the ISO 14230-4/ISO 9141-2 interface with 5 baud (refer to B.3 for information on how
to perform the 5 baud initialization and protocol detection of the ISO 14230-4/ISO 9141-2
protocols).
6 © ISO 2014 – All rights reserved
ii) If the initialization sequence is completed successfully, then the vehicle’s OBD protocol is
either ISO 14230-4 or ISO 9141-2.
5) Test for ISO 15765-4
i) Legacy vehicles were previously allowed to use the contacts now defined for CAN
communication as manufacturer discretionary. The external test equipment shall ensure
adequate protection from these legacy signals.
ii) Perform the “external test equipment initialization sequence” defined in ISO 15765-4.
iii) If the initialization sequence specified in ISO 15765-4 is completed successfully, then
ISO 15765-4 is the vehicle’s OBD protocol.
Both ISO 9141-2 and ISO 14230-4 specify a time within which a module(s) that has successfully been
initialized must receive a message or the module(s) will return to the address mode. To maintain
communication with the vehicle in case no service request is needed at this moment, the external test
equipment shall send an idle message.
For vehicles using ISO 9141-2, the service 0x01 PID 0x00 request shall be used as the idle message.
For vehicles using ISO 14230-4, the service TesterPresent is the recommended way to satisfy the idle
message requirement as specified in ISO 14230-4. Alternatively, the service 0x01 PID 0x00 as specified
in ISO 15031-5 may be used.
If during the initialization of the ISO 15765-4 (DoCAN) protocol the external test equipment receives
a negative response message(s) from the emissions-related ECU(s) with the negative response code
(NRC) 0x21 busy-RepeatRequest, the external test equipment is required to perform five retries (repeat
request message as specified in ISO 15765-4). The reception of NRC 0x21 busy-RepeatRequest during
the initialization indicates that an on-board diagnostic tester may be active and is currently diagnosing
one or multiple emissions-related ECUs. The on-board tester and vehicle ECU(s) shall complete the in-
progress communication. This may take several seconds. The external test equipment shall continue to
initialize the ISO 15765-4 protocol until it receives at least one positive response or until it aborts after
two seconds have expired (measured after the completion of the fifth retry).
If none of the protocol tests shown in 9.1 succeeds, the external test equipment shall repeat all of them
and advise the user
a) that communication with the vehicle could not be established,
b) to confirm that the ignition key is in the “ON ” position,
c) to check the emissions label or vehicle service information to confirm that the vehicle is OBD
equipped, and
d) to confirm that the external test equipment is connected to the vehicle correctly.
The equipment shall continue to repeat the protocol tests shown in 9.1 until either one of them passes
or the user chooses to abandon the attempt. The equipment may also indicate the number of failed
initialization attempts to the user.
9.2 Multiple tester communication
9.2.1 General
If the vehicle utilizes in-vehicle test equipment [e.g. intelligent instrument clusters, Human-Machine
Interface (HMI) modules, data loggers, or telematics gateways], then there is always a possibility that a
second tester (one internal tester and one external tester) sends a diagnostic request while the ECU is
busy processing a diagnostic request from the first one.
The correct behaviour is that a legislated request from an external test equipment shall always receive
a response within P2 timing. It is up to the vehicle manufacturer to decide whether other requests shall
also be processed.
The behaviour within a multiple tester scenario depends on the capabilities of the transport layer used.
If the server can process multiple diagnostic requests simultaneously and the transport layer allows
different sender and receiver addresses, then there is no conflict. The servers shall maintain separate
state information for the different tester instances and thus, react depending on that state information.
For more detailed information relative to possible server implementations, refer to ISO 14229-1.
9.2.2 Behaviour of external test equipment
The external test equipment can normally start a communication setup as specified and the internal
tester would detect it.
To allow vehicle internal clients to re-establish vehicle internal diagnostic communication, the external
client shall stop sending any diagnostic request message if there is no user interaction for at least 5 min.
9.3 Handling of no response from the vehicle
A vehicle module may fail to respond to a request message from the external test equipment because
of incorrect transmission or because the module does not support that message. If a response is not
received within the time-out period prescribed by the protocol, the external test equipment shall
perform the following:
a) retransmit the request message;
b) if there is still no response, transmit a service 0x01 PID 0x00 request message to determine if
communication with the vehicle is currently possible and if the data desired is available;
c) if a service 0x01 PID 0x00 response is received, transmit other messages, if available, to determine
whether the desired data are supported by the vehicle;
d) if a), b), and c) fail, then indicate to the user, as appropriate, that communication with the vehicle
cannot be performed, that communication with the module cannot be performed, or that the
information the user has selected is unavailable.
For compatibility to enhance diagnostic communication (i.e. ISO 14229-3) and to make the functionality
of the external tester more robust, the following mechanism is allowed:
— If data are received from one control module, then the external test equipment is allowed to restart
its timer in order to wait for further responses from other control modules. This is called P2 .
reload
9.4 Handling of multiple responses from the vehicle
The external test equipment shall be capable of interfacing with a vehicle in which multiple modules
support OBD requirements.
The external test equipment shall create an internal table in its memory to maintain a list of modules
and the responses associated with those individual modules. The external test equipment shall not
make any assumptions about the order in which modules respond at any time to any request.
The external test equipment shall inform the user when multiple modules respond to the same request.
The external test equipment shall inform the user when multiple modules respond with different values
for the same data item.
The external test equipment shall provide the user with the ability to select for display, as separate
items, the responses received from multiple modules for the same data item.
8 © ISO 2014 – All rights reserved
9.5 Message structure
Communication between the external test equipment and the vehicle consists of repeated cycles of the
external test equipment issuing a request message to the vehicle module(s) and the vehicle module(s)
responses. The structure of these messages is specified in ISO 15031-5. ISO 15031-6 specifies the usage
of diagnostic trouble codes, which may be contained in response messages. ISO 15031-2 specifies the
approved terms, PID acronyms, and module names which may be contained in response messages.
9.6 Diagnostic trouble codes monitoring
The external test equipment shall be capable of continuously obtaining, converting, and displaying OBD
emissions-related DTCs from the vehicle. The DTC, its descriptive text, or both shall be displayed. DTCs
and their descriptive text are specified in SAE J2012-DA. The external test equipment shall continuously
obtain and display DTCs while this facility is selected.
If the protocol is ISO 15031-5 and the response message includes a DTC number equal to 0x0000, the
data reported may not be valid and shall not be displayed.
9.7 Obtaining and displaying OBD emissions‑related current data, freeze frame data,
and test parameters and results
The external test equipment shall create an internal table in its memory to maintain a list of supported
PIDs/OBDMIDs/TIDs/ITIDs for each ECU that responds to a service request message with the requested
“Supported PID/OBDMID/TID/ITID” (0x00, 0x20, . 0xC0). If bit 0 of Data D is reported as 0, that indicates
that no additional PIDs/OBDMIDs/TIDs/ITIDs are supported by that ECU. If bit 0 of Data D is reported
as 1, that indicates that additional PIDs/OBDMIDs/TIDs/ITIDs are supported by that ECU. The external
test equipment does not need to request any additional “Supported PIDs/OBDMIDs/TIDs/ITIDs” if bit 0
of Data D is reported as 0 by all ECUs.
The external test equipment shall test for support of, e.g. PID 0x4F and 0x50 which include external test
equipment configuration information. If supported, the modified scaling factors provided by these two
PIDs shall be applied by the external test equipment when requesting those PIDs listed in the PID 0x4F
and 0x50 definitions (see SAE J1979-DA).
The external test equipment shall only display data from an ECU if that ECU indicated that it supports
that data item. The external test equipment shall not display data from an ECU if that ECU indicated that
it does not support that data item.
The external test equipment shall be capable of obtaining, converting, and displaying the following:
a) OBD emissions-related current data as described in SAE J1979-DA specifying all emissions-related
data. For each data item, an external test equipment display text string and the formatting of the
−1
data value is specified (e.g. RPM: xxxxx min );
b) OBD emissions-related freeze frame data [same data display as specified in a)];
c) test parameter and result data as described in SAE J1979-DA. SAE J1979-DA details what data are
available, the messages to be used to request the data, the messages to be used to return the data,
the conversion values for the data, and the format to be used to display the data.
When current data items are selected for display, the external test equipment will continuously request
from the vehicle the data to be displayed and will display the data received in the corresponding response
messages. When freeze frame or test parameters and results are selected for display, the external test
equipment does not need to continuously request and display those items except test parameters and
results for Misfire Monitor.
Where applicable, the external test equipment shall indicate whether a test limit is a high limit or a low
limit. Where applicable, the display of test results shall also show the TID and component ID.
Data from the vehicle may indicate which items are supported, in which case this information shall be
made available to the user by the external test equipment. The external test equipment shall also allow
users to specify requests for services, parameters, test IDs, etc., irrespective of whether the vehicle has
indicated support for such items.
9.8 Code clearing
The external test equipment shall be capable of sending a request to clear OBD emissions-related DTCs,
freeze frame data, and diagnostic tests status information. The external test equipment shall require
the user to confirm such a request prior to transmission.
9.9 On-board diagnostic evaluations
9.9.1 Completed on‑board system readiness tests
Immediately after the external test equipment has successfully established communication with the
vehicle, it shall check the status of the system readiness tests. If the supported tests have not all been
completed, the external test equipment shall indicate to the user: “Not all supported on-board system
readiness tests have been completed” or equivalent. The equipment shall also allow the user to identify
any readiness tests that have not been completed.
9.9.2 Supported on‑board system readiness tests
The external test equipment shall indicate to the user which of the tests specified in SAE J1979-DA by
ISO 15031-5 service 0x01 PID 0x01 data B – D are supported and which of these have been completed.
Byte B, Bit 3 shall be used to differentiate between spark ignition gasoline and compression ignition
diesel vehicles. The readiness information displayed shall be appropriate for the ignition fuel type.
NOTE The implementation of Byte B, Bit 3 in the vehicle depends on different local legislation.
9.9.3 Malfunction Indicator Lamp (MIL) — status and control
The external test equipment shall be capable of indicating whether the MIL has been commanded ON
and if so, by which module or modules.
9.10 Use of StopCommunication service associated with ISO 14230-4 (optional)
When ISO 14230-4 is being used to support OBD requirements in a vehicle, the external test equipment
may provide to the operator the ability to select the StopCommunication service defined for ISO 14230-4.
10 User interface
10.1 Display
The external test equipment shall be capable of displaying simultaneously at least two items of OBD
emissions-related current data items, emissions-related freeze frame data items, or emissions-related
diagnostic trouble codes. A list of the OBD current data and freeze frame data items, their parameter IDs,
data resolution, data conversion information, units, and display formats is provided in SAE J1979-DA.
The display shall be capable of displaying alphanumeric characters. The display shall at least support
the SI units as specified in SAE J1979-DA. The unit conversions specified in SAE J1979-DA shall be used.
DTCs shall be displayed as specified in A.3.2.
As a minimum, the data values of two data items shall be displayed simultaneously. A display of the
parameter IDs of the data items and the IDs of the modules that supplied the data items must be easily
accessible if not displayed with the data values.
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The units of measurement associated with the data items shall either be
— displayed with the data values,
— easily accessible on the display, or
— readily available to the user (e.g. on the body of the external test equipment).
Having this information available in a user manual separate from the body of the external test equipment
does not satisfy this requirement.
10.2 User input
The external test equipment shall allow the user the following services as specified by ISO 15031-5.
a) Select between the basic functions required by OBD, e.g.
1) system readiness test status display,
2) MIL status and control,
3) display current data,
4) display freeze frame data,
5) display diagnostic trouble codes,
6) clear emissions-related data,
7) display test parameters and results, and
8) read vehicle identification.
b) Select for simultaneous display of at least two OBD emissions-related items of any one of the
following categories:
1) current data;
2) freeze frame data;
3) diagnostic trouble codes;
4) test parameters and results.
c) Confirm a request to clear and/or reset OBD emissions-related diagnostic information.
d) Request operation of an on-board system, test, or component.
Responses from multiple modules to requests for a current data item or a freeze frame data item are
treated as separate data items for selection and display purposes.
11 Power requirements
11.1 Vehicle battery voltage support
11.1.1 External test equipment supports only 12 V d.c. vehicle battery voltage
If the test tool manufacturer chooses to develop external test equipment with only 12 V d.c. vehicle
battery voltage support, the following requirements shall apply:
— operate normally within a vehicle battery voltage range of 8,0 V d.c. to 18,0 V d.c.;
— survive a vehicle battery voltage of up to 24,0 V d.c. for at least 10 min;
— survive, non-operationally, a reverse vehicle battery voltage of up to 24,0 V d.c. for at least 10 min.
Preferably, the external test equipment will withstand cranking, in that communications and data shall
not be lost during vehicle battery voltage reductions to 5,5 V for up to 0,5 s. The display ne
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