II
`
`II
`
`rt ti n
`luti n
`
`Proceedings of the
`1994 International Congress on
`Transportation Electronics
`
`P-283
`
`CONVERGENCE
`
`NINETY-FOUR
`
`G.lOBAJ. MOBiliTY DATABASE
`All SAE papers, standards, and selected
`books are abstracted and indexed in the
`Global Mobility Database.
`
`Published by:
`Society of Automotive Engineers, Inc.
`400 Commonwealth Drive
`Warrendale, PA 15096-0001
`USA
`Phone: (412) 776-4841
`Fax: (412) 776-5760
`October 1994
`
`IPR2013-00415 - Ex. 1009
`Toyota Motor Corp., Petitioner
`1
`
`

`

`SAE ISBN 1-56091-548-X
`Library of Congress Catalog Card Number: 94-67471
`
`IEEE ISBN 0-7803-2421-8 (Casebound)
`0-7803-2422-6 (Microfiche)
`
`IEEE Catalog Number: 94CH35729
`
`Copyright 1994 Convergence Transportation Electronics Association
`
`The materials contained in this publication
`are protected by copyright. Any form of
`copying or reproduction, electronic or other(cid:173)
`wise, is prohibited without the express writ(cid:173)
`ten consent of Convergence Transportation
`Electronics Association. The positions and
`opinions expressed in these materials are
`those of the authors, and do not necessarily
`represent the positions or opinions of
`
`Convergence Transportation Electronics
`Association. Convergence Transportation
`Electronics Association assumes no respon(cid:173)
`sibility for errors or omissions in any written
`materials, nor does it endorse any products
`or services discussed in any such materials.
`
`Printed in USA
`
`2
`
`

`

`94C055
`Prospects for Failure Diagnostics of
`Automotive Electronic Control Systems
`
`Takaaki Mogi
`UNISIA JECS Corp.
`
`ABSTRACT
`
`Automotive electronics since the 1970s has become
`a more sophisticated technology. Diagnostic systems
`designed to prevent vehicle troubles have developed in
`various stages. At present, it is possible to detect a specific
`problem through a forecast technique of several events;
`this represents a major difference from the simple short
`circuit detection of a particular point that was an important
`diagnostic event in the initial stage. In order to produce
`more efficient and effective as well as consumer-satisfying
`vehicles, it is necessary to develop versatile technologies
`that furnish solutions to global environmental problems,
`automotive safety, intermittent troubles, and various driver's
`In this paper, the author discusses the
`requirements.
`future goals of diagnostics technology, and suggests
`possible avenues for technological research.
`
`INTRODUCTION
`
`There are two types of automotive trouble-detecting
`systems: onboard and offboard diagnostics. This paper
`will define onboard and offboard diagnostics and describe
`each of the three-stage development of the diagnostic
`systems.
`It will also introduce diagnostic systems tools
`employed by Japanese automotive manufacturers.
`Standardization of diagnostic systems, such as the SAE
`J1850 standard, and legislation in California and the other
`states of the U.S.A. contribute to further improvement of
`onboard diagnostics.
`To make a diagnostic system flexible, inexpensive,
`and highly reliable, there are a number of outstanding
`issues to overcome. Present diagnostic technology needs:
`• Further improvement of diagnostic functions
`• Simplification and improved diagnostic precision
`• Addition of failure predicting functions
`
`477
`
`• Study of remedy technology
`These improvements are possible, and some concrete
`examples are shown.
`
`DEFINITION OF DIAGNOSTICS AND SYSTEM
`STRUCTURE
`
`Diagnostics is defined as the "detection of a faulty
`component and malfunctioning element causing a control
`system failure" in the ISO and SAE standards as well as in
`the JASO standard in Japan. Commercially available
`diagnostic systems are of two types: onboard (diagnostic
`function control and components are mounted on the
`electronic controller of the car) and offboard diagnostics
`(using external devices.) A diagnostic system is typically
`connected to an onboard vehicle electronics system as
`shown in Figure 1.
`
`ONBOARD DIAGNOSTICS- An onboard diagnostic
`system receives control data from the ECU via a diagnostic
`connector mounted on the vehicle and then records this
`data. The most popular diagnostic system in use comprises
`an ECU with a communication function and an intelligent
`diagnostic system, both of which are interconnected for
`serial communication to read the data. Another popular
`diagnostic system incorporates an actuatorwhich is driven
`for active testing. Onboard diagnostics function to
`G) detect an abnormality during system operation and
`® detect an abnormality during a diagnostic test.
`
`OFFBOARD DIAGNOSTICS- An offboard diagnostic
`system receives signals from the ECU connectors and the
`connector specially used for diagnosis through aT-branch
`and then measures these signals. A variety of general(cid:173)
`purpose measuring instruments such as digital multimeters,
`oscilloscopes and data recorders are commercially
`available for this purpose. One of the advantages of the
`offboard diagnostic system is that there is no special
`
`3
`
`

`

`burden on the ECU for diagnostics. This system can <D
`check and detect a failure with a general-purpose tester
`and ® input the experience of technicians to detect an
`abnormality using an expert system. An overview of a
`diagnostic system structure is described below (Figure 2).
`For the purpose of illustration, it is divided into four
`
`subsystems: onboard display and failure code display for
`the onboard diagnostics, and on-line (with a function to
`control communication with the car) and off-line (without
`the communication control function) diagnostics for the
`offboard diagnostics.
`
`AID converter
`
`CPU
`
`ECU
`
`Fig. 1 Diagnostic Unit Connections
`
`Offboard
`diagnostics
`
`~~ttj;~~l,~~~ Onboard
`diagnostics
`
`Onboard diagnostics
`
`Onboard display
`
`Display results of diagnostics
`on CRT
`
`Fig. 2 Structure of Diagnostic System
`
`(JASO Diagnostics Terminology for Vehicle Electronic Control Systems, The Society of Automotive Engineers of Japan)
`478
`
`4
`
`

`

`HISTORY OF DIAGNOSTIC TOOLS
`
`Diagnostic tools have been developed in three stages
`since the 1970s, as shown in Figure 3. The Figure shows
`how the four subsystems have been developed. The
`stages of development are attempt (1st stage), onboard
`diagnostics (2nd), and offboard diagnostics interacting
`with a self diagnostic function (3rd).
`
`------
`
`History of diagnostics
`
`~ Onboard display
`.8 c
`s 0
`0 ;;;
`Troubie code display
`1:;- ~
`.!.! ;;;
`Cl) ..
`0 c
`i5
`
`On-line diagnostic
`~ system
`~
`0
`
`Off-line diagnostics
`
`~~·
`
`1970
`
`Stage I \
`
`(Attempt to diagnosJ'
`
`·Monitor function I
`
`..
`
`Diagnostic system
`IIIII
`
`FIRST STAGE (early to mid-1970s) -A tool called a "T(cid:173)
`joint"- the same type used in analog electronics- was used
`in the initial stage of microcomputer-control of vehicles.
`Figure 4 shows a typical T -joint diagnostic tool. AT-shaped
`harness is connected between the ECU and the chassis
`harness to branch 1/0 signals, which are then directly
`monitored for diagnosing.
`
`1980
`
`Stage 2
`(Use on board
`
`"
`\
`diagnostics) j
`
`I'
`
`1990
`
`(year)
`
`Stage 3
`(Use offboard diagnostics with
`self -diagnostic function)
`
`Self diagnostics function
`
`Trouble code display
`
`Handheld offboard
`diagnostic system
`
`Logic console type diagnostic system •
`.
`
`Information retrieval system •
`
`Expert system
`
`Engine tuning tester/integral engine tester
`
`Fig. 3 Trends of Diagnostic Technology
`
`connector
`
`Under rear seat
`
`I )\_
`
`Fuel pump connector
`
`Fig. 4 Example of aT-Joint Type Tool
`
`(Toyota 1G-EU, 1G-GEU, 1G-EJ Engine Repair Manual, March 1986)
`
`479
`
`5
`
`

`

`Various diagnostic techniques were studied during this
`period. On board diagnostic units introduced in this period
`included an OK monitor with a display and alarm function
`- an item which still comprises the basic features of
`diagnostic monitors today.
`Off board diagnostics required the frequent use of general(cid:173)
`purpose testers such as ammeters and voltmeters as well
`as special-purpose testers such as engine analyzers. An
`on-line diagnostic unit with a microcomputer was also
`introduced. Onboard diagnostic systems were considered
`effective tools during this period.
`
`SECOND STAGE (mid-1970s to mid-1980s)- The
`automotive industry gradually moved from offboard to
`onboard diagnostics in the second stage. In 1977, GM
`announced the world's first engine control system with an
`integrated microcomputer and, at the same time, adopted
`an onboard diagnostic system with self-diagnostics. This
`system attracted great attention; the use of a microcomputer
`for control purpose eliminated the need for additional
`hardware because the diagnostic function was easily
`achieved by means of the software. Engines and other
`control systems were further controlled electronically using
`microcomputers, and many other vehicle assemblers
`announced their own on board diagnostic systems, including
`self diagnostics. Many onboard displays were introduced
`and these became popular toward the beginning of the
`1980s.
`In the onboard diagnostic systems, the result of self(cid:173)
`diagnostics was indicated by flashing alarm lamps on the
`instrument panel using failure codes, or shown numerically
`on the display of the air conditioner unit (Figure 5).
`
`THIRD STAGE (Mid-1980s on) - Self-diagnostics
`was enhanced during this third stage, while a new offboard
`diagnostic system, with functions closely related to self(cid:173)
`diagnostics, was introduced~ Self-diagnostic equipment
`was in greater demand because serviceability had to be
`enhanced as electronic control systems became
`increasingly sophisticated. Advanced self-diagnostics was
`also effective for reducing the expense of warranty claims.
`Conventional self- and offboard diagnostics were insufficient
`to meet these needs when used separately.
`The new offboard diagnostic system allows for data
`transmission of the results of onboard diagnostics, or the
`condition of a vehicle, to offboard equipment via a special
`connector. There the transmitted data are displayed or
`used to identify the faulty component using diagnostic
`software. Taking a lead in the competition, Mitsubishi
`Motors announced, in October 1987 a full-featured offboard
`tool called the "Multi-Use Tester," shown in Figure 6.
`Competitors released similar units after the announcement
`of the "Multi-Use Tester'' by M itsubishi Motors. This created
`a new situation for diagnostic systems for testing onboard
`electronic equipment. The Mazda DT -S1 000 is shown in
`Figure 7. Its simple key operation allows the technician to
`retrieve data for diagnostics from the ECU, or run an Active
`Test of the actuator operation using the ECU. Figure 8
`shows the Nissan CONSULT diagnostic tool featuring
`timers and other instruments in addition to an AID converter.
`
`(!)
`
`Short test tenninals
`
`(2)
`
`Read the number of flashes
`
`(3)
`
`Look up the number in code list
`
`Fig. 5 Onboard Diagnostics
`(Sugino: Development of Diagnostic Unit, Daihatsu
`AXIS, No. 1 02, 1992)
`
`Fig. 6 Mitsubishi Motors Multi-Use Tester
`(Kubozono: Development of Car Electronics Diagnostic
`System, Mitsubishi Motors· Technical Review, No. 1,
`1988)
`
`Fig. 7 Mazda DT-S1000
`(Mazda Eunos 500 Maintenance Manual, January 1992)
`
`480
`
`6
`
`

`

`The Bosch KTS-300 is depicted in Figure 9. Bosch
`developed a proprietary diagnostic system for its own
`products and is actively marketing this system on its own,
`not in cooperation with automotive companies. Finally,
`Figure 10 shows the GM TECH-1, a tool with functions
`
`similar to all of the above systems.
`Despite the initial enthusiasm for offboard diagnostics,
`it was not popular with car repair shops as expected. The
`reasons for this included: its narrow diagnostic range and
`insufficient accuracy, high price, and recurring cost.
`
`PRESENT STATE AND CHANGES IN DIAGNOSTIC
`TECHNIQUES
`
`PRESENT STATE OF JAPANESE CAR
`ASSEMBLERS - Japanese car assemblers announced
`diagnostic systems after the Mitsubishi Motors' "Multi-Use
`Tester" was launched. Today, they are all independently
`developing proprietary systems - with the exception of
`lsuzu and Suzuki which are using the GM TECH-1 -and are
`actively marketing their own systems. Table 1 is a list of
`such tools being marketed:
`
`FORECASTING ENVIRONMENTAL CHANGES(cid:173)
`, depletion of the ozone layer by
`Global warming due to C02
`chlorofluorocarbons (CFCs) and acid rain due to SOx and
`NOx are some of the typical phenomena contaminating the
`atmosphere and soil of the earth. To alleviate or control
`these problems and protect the environment, governments
`throughout the world are reinforcing their own environmental
`regulations. Figure 11 shows the regulations in the United
`States. In the State of California, the law requires the
`installation of a diagnostic system for emission-related
`equipment and an alert message to the driver to prevent air
`pollution. At present, a diagnostic system for emission
`purifying equipment (02 sensor, EGR valve, etc.) and an
`alert message to the driver must be installed from 1988
`model vehicles on (OBDI). From the 1994 model vehicles
`on, the compulsory provision will be extended to cover a 3-
`way catalyst conversion rate monitor, misfire monitor, etc.
`The regulations are being reinforced even further with the
`new OBD-11 (see Table 2) which requires that the service
`technician be able to monitor the diagnostics via a serial
`data communication system. The OBD-11 requires the use
`of low-to medium-speed communication protocols reviewed
`and standardized by SAE (J 1978) and ISO (9141 ), together
`with the relevant diagnostic connectors, tools and
`procedures. This is one of the important diagnostics
`standardization activities now being implemented.
`Figure 12 shows one example of OBD-11 diagnostic
`tools.
`
`UPCOMING TECHNOLOGICAL TRENDS -
`Considering the evolution of car electronic systems from
`the viewpoint of performative functions, much of the
`functionality of power train control and chassis control
`systems has been, so far, intensively improved. In terms
`of hardware, we anticipate control systems to be further
`integrated and decentralized to optimize system capabilities.
`Car electronics systems should therefore continue to be
`developed- not as auxiliary equipment for machines, but
`as their replacements, with a priority on failure forecasting.
`At the same time, their intelligent capability should be
`developed in order that appropriate countermeasures can
`be taken when a failure is forecasted. We think it is
`
`Fig. 8 Nissan CONSULT
`(Yamaoka: Hi-Tech Diagnostic Unit, Nissan CONSULT,
`Automotive Engineering, Vol. 39, No.8, July 1990)
`
`Fig. 9 Bosch KTS-300
`(Bosch catalog)
`
`Fig. 1 0 TECH-1
`(U.S. patent 4694408 publication)
`
`481
`
`7
`
`

`

`Table 1 Offboard Diagnostic Systems of Japanese Car Assemblers
`
`Name
`
`Systems covered
`
`Display
`
`Operation panel
`
`Major Diagnostics display
`functiofl
`
`Diagnostics reset
`
`RAM data display
`
`Isuzu
`
`TECH I
`
`ENG, AT
`
`Suzuki
`
`FNG
`
`Toyota
`Nissan
`Subaru
`Honda
`Diagnosti- CONSULT Not
`Subaru
`TECH1A Select
`cs code
`decided
`reader
`yet
`Monitor
`ENG, AT, ENG, AT, ENG,ABS,
`4WS, etc. ABS, etc. HI CAS,
`etc.
`
`ENG
`
`Mazda
`Dr-
`SIOOO
`
`All
`systems
`
`Mitsubishi
`Multi-Use
`Tester
`
`ENG, AT,
`suspensio
`n, etc.
`
`LCD(BL)
`16 keys
`
`LCD(BL) LCD-(BL) LCD, LED LCD
`6SW
`20 keys
`16 keys
`16 keys
`
`LCD(BL) LCD(BL) LCD
`Touch
`23 keys
`Touch
`switch
`screen
`
`0
`
`0
`
`0
`
`0
`
`0
`
`0
`
`0
`
`0
`
`0
`
`0
`
`X
`
`0
`
`0
`
`0
`
`0
`
`0
`
`0
`
`X
`
`0
`
`0
`
`0
`
`0
`
`0
`
`0
`
`0
`
`0
`
`X
`
`0
`
`0
`
`0
`
`0
`
`X
`
`X
`
`0
`
`X
`
`0
`
`0
`
`0
`
`0
`
`0
`
`0
`
`0
`
`0
`
`1/0 signal display
`Generate output
`signal
`Generate quasi-
`signal
`
`Trace upon failure
`
`External
`communication
`Type/year model
`compatibility
`Display
`specifications
`
`X
`
`0
`
`0
`
`0
`
`0
`
`0
`
`0
`
`0
`
`X
`
`X
`
`X
`
`X
`
`0
`
`0
`
`X
`
`0
`
`0
`
`0
`
`X
`
`0
`
`0
`
`0
`
`0
`
`0
`
`0
`
`0
`
`0
`
`X
`
`0
`
`'0
`
`0
`
`0
`
`0
`
`0
`
`0
`
`0
`
`X
`
`Note: BL with backlight; o available; x not available
`Sugino: Development of Diagnostic Unit, Daihatsu AXIS, No. 102, 1992)
`
`HC
`g/mile
`
`co
`g/mile
`
`NOX
`g/mile
`
`Modele
`Year
`
`Fleet
`Share
`
`(Reinforced
`0.4
`40%
`1993
`regulations)
`-·-·-·-·-·-·+----+-----+-----!
`
`0.4
`
`1994
`
`10%
`
`(TLEV)
`
`0
`
`0
`
`0
`
`·1998
`
`2%
`
`(ZEV)
`
`1997
`
`25%
`
`(LEV)
`
`·-·-·-·-·-·-·-·-·-·-~---+----+----;
`
`1997
`
`2%
`
`(ULEV)
`
`Fig. 11 Emission Control in North America
`482
`
`8
`
`

`

`Table 2 OBD-11 Diagnostic Logic
`
`Item
`
`Legal requirements/contents of diagnostics
`
`Catalyst
`diagnostics
`
`Light MIL when HC conversion efficiency of
`catalyst falls to 60% or below
`
`Diagnostic technique
`One Oz sensor each is installed before and after
`the catalyst, and their signals are compared to
`determine the HC conversion efficiency of the
`catalyst.
`
`Misfire monitoring Light MIL on detecting a misfire that is likely
`to damage the catalyst or that exceeds 1.5 times
`the emission control level.
`
`Misfire is determined by measuring change in
`engine speed for each ignition timing with a
`ring gear sensor.
`
`Fuel system
`monitoring
`
`Light MIL when an abnormality in the fuel
`system exceeds 1.5 times the emission control
`level. Clogged or leaking injector, leaking
`intake air, abnormal fuel pressure, etc.
`
`Fuel system is determined abnormal when the
`learning value of A. control with 0 2 sensor is
`abnormal (mixture is extremely rich or lean).
`
`Oz sensor
`monitoring
`
`Light MIL when output voltage or response
`speed exceeds 1.5 times the emission control
`level.
`
`Abnormality is determined by rich/lean
`response time of two Oz sensors and voltage.
`
`EGR monitoring
`
`Determine abnormal EGR flow rate by
`Light MIL when EGR flow rate is too large or
`small, exceeding 1.5 times the emission control measuring temperature change in EGR flow
`level.
`path with an EGR temperature detector. BPT
`valve failure is determined upon detecting a
`misfire.
`
`Secondary air
`Light MIL when the secondary air flow rate is
`system monitoring below 1.5 times the emission control level.
`
`Abnormal secondary air flow rate is determined
`by reading 0 2 sensor signals by providing a
`secondary air jet opening in the upstream of
`0 2 sensor.
`
`Evaporator leak
`monitoring
`
`Leak is determined upon detecting a change in
`Light MIL when the evaporator system causes
`pressure in evaporator check pressure sensor
`HC vapor to leak into the atmosphere. (Leak
`from a hole about I mm in diameter.) Effective when the evaporator line between fuel tank and
`canister closes in negative pressure.
`from 1996 models.
`
`Monitoring of
`Light MIL when any component or system
`other emission
`related to emission performance malfunctions.
`related components Vehicle speed sensor, crank angle sensor,
`throttle sensor, water temperature sensor,
`neutral switch, knock sensor, ISC valve, purge
`valve, VTC valve, electronic control A/T, etc.
`
`Determine by checking wires for breakage or
`by using an operation mode in which normal
`operation can be confmned.
`
`483
`
`9
`
`

`

`important to define a new architecture for car electronics
`systems and to research and develop diagnostic systems
`that comply with that architecture.
`
`Diagnostic
`c:apabilily 50
`(%)
`
`SEF139P
`
`'60
`
`'70
`
`• 80
`
`'90
`
`(year)
`
`Fig. 13 Diagnostic Method Trends
`
`-
`1::::--
`1 Data link connector
`for GST // ~
`yr-Center console side cover__.----
`/ 1 -~ SEF140P
`
`Fig. 12. OBD-11 Scan Tool
`
`CURRENT TASKS- Figure 13 shows the ratio of
`detection items required for diagnosing car electronics
`systems and parts, to the inspection items that current
`diagnostic systems already have in place. Currently,
`onboard and offboard diagnostics can cover about 20% of
`all car electronics systems and parts; we still owe much to
`the skills of service technicians, as well as conventional
`general-purpose testers and troubleshooting manuals.
`
`Why are diagnostic functions currently at a low level? The
`following reasons can be offered:
`1.
`Identify failure locations and parts.
`2. Detect wiring breaks and short-circuits.
`3.
`Implement self-diagnostic functions in the
`microcomputer.
`As far as onboard diagnostics is concerned, all ofthem are
`relatively inexpensive and technically easy to solve.
`
`Offboard diagnostics, on the other hand, will require
`solutions to the following problems:
`1. There are many modifications, expansion, etc.
`required for the scope of diagnostics, and activity in
`this area has been inadequate.
`2. There has been an attempt (see Figure 14) to create
`a non-reproducible failure diagnostic system, but the
`capability of the diagnostic software and hardware is
`still inadequate.
`3. Equipment is still difficult to operate and diagnostics
`requires a considerable amount of time.
`4. Diagnostic tools are expensive and their use is not
`widespread.
`
`ICcard
`
`EGI harness
`
`DRIVE RllCOHDER LJ
`
`I II II I I I I I
`
`Public lines
`
`-~~GP-10
`. E_J'
`Modem
`""'-
`RS·232C
`
`~Centronics ~ (parallel)
`
`Printer/ploller
`
`Embedded backup bauery
`
`Boost sensor
`
`Compatible with various types of C/U by replacing the T-branch
`Backup battery charger
`harnes~ in the figure.
`Fig. 14 Nissan Drive Recorder
`484
`
`10
`
`

`

`FUTURE TRENDS OF DIAGNOSTIC TECHNIQUE
`
`Multiple ECUs are now being installed in conventional
`car electronics systems to meet the needs of engine, AT
`and ABS, respectively. These individual control functions
`are likely to be integrated into a single, sophisticated
`control system sometime in the future. Generally, the
`diagnostic system must have improved function and offer
`more customer satisfaction.
`
`Each diagnostic process comprises four stages as
`shown in Figure 15. Many systems are not only capable of
`detecting a problem, but also of identifying the defective
`component and forecasting the severity of the problem
`detected. A diagnostic system must generally include a
`function to "forecast a major defect and resolve it by
`monitoring, for example, the frequency of minor defects
`and performance deterioration." (26) Table 3 compares
`typical diagnostic techniques in terms of several items.
`
`..
`
`~
`
`Detect
`
`Failure
`
`_ ... Discern
`
`...
`
`Forecast
`
`..
`
`Solve
`
`Identify problem
`
`Fig. 15 Functions of Diagnostics
`
`Table 3. Comparison of Typical Diagnostic Methods
`
`Area
`Classification
`Deter- Observer method
`min a-
`tion Method by
`system vector
`concept
`
`Parity vector method
`
`Vector gradient
`method.
`
`Fore- Method by
`cast
`hypothesis
`system testing
`
`Residual sum of
`squares method
`Generalized
`likelihood ratio
`testing method
`Sequential
`probability ratio
`testing method
`Method by information theory
`
`Diagnostics based on
`Kullback's information.
`Multiple hypothesis Hypothesis testing for
`on-line identification
`testing method
`
`Method by
`identification
`
`Diagnostic method
`Compare observer and
`sensor output
`Compare sensor outputs
`with a model
`
`Relationship of sensor
`error output in vector
`space
`Diagnostics by testing
`residual series from
`Kalman filter, etc.
`
`Target of
`diagnostics
`Sensor
`
`Sensor
`
`Features
`Redundant sensors not
`required
`Ditto. Various methods
`are available
`
`Sensor
`
`Ditto
`
`System
`
`Fault detection only
`
`System element
`
`Up to fault
`identification
`
`System element
`
`System element
`
`System element
`
`Sequential calculation
`type. Short calculation
`time
`Pattern comparison
`
`Able to diagnose
`physical parameters
`
`485
`
`11
`
`

`

`FURTHER IMPROVEMENT OF DIAGNOSTIC
`FUNCTIONS-
`1. Enhanced Diagnostic Function by System Integration
`Car control systems will become ever complex due to
`technological improvements as well as impacts from outside
`the automotive industry such as stringent exhaust emission
`controls. It is expected that car control systems will become
`far more complex due to the integration of an engine
`control system and an AT control system, and also the
`integration of a chassis control system. The functions of a
`diagnostic system must be enhanced to accommodate
`new requirements arising from the above trends.
`
`2. Effective Utilization of Information between car control
`systems via On-Vehicle LAN, etc.
`Efficient utilization of information is possible because
`information from onboard diagnostic systems is already
`exchanged between various control systems (ex. engine
`control, AT control, traction control system and ABS) via
`LAN.
`
`3.
`
`Increased Interaction between Onboard and Offboard
`Diagnostics
`Onboard diagnostics are capable of detecting failures
`which are difficult to discover, such as intermittenttroubles.
`Off board diagnostics have the merit of great flexibility. A
`combined onboard and offboard diagnostic system that
`features all of the merits of each system is ideal.
`
`4. Creation of Nonreproducible Failure Detecting
`Techniques
`It is difficult to discover intermittent failures, but it may be
`possible by collecting input/output data until a failure is
`discovered, such as a flight recorder used in an aircraft.
`
`SIMPLIFICATION OF DIAGNOSTIC METHOD
`AND ACCURACY IMPROVEMENT-
`1. Reinforcement of new diagnostic logic such as use of
`expert systems;
`2. Development of database for service technology data
`and improvement of on-line retrieval system;
`Improvement of signal processing technique by
`incorporating powerful microcomputers (ex. 32-bit,
`RISC) capable of performing accurate, high-speed
`computation and analysis.
`
`3.
`
`ADDITION OF FAULT FORECAST FUNCTION -A
`diagnostic technique must be developed to <D detect
`deterioration of the purification performance of exhaust
`gas,® detect vehicle movement and braking performance
`due to defective structural components in the control
`system, and® to forecast performance deterioration and
`inform the driver or service technician accordingly.
`Forecast techniques are divided into forecasting defects in
`alternative characteristics (model-based) and changes in
`characteristics leading to a defect.
`
`Forecast of defects in alternative characteristics
`(model-based)- The following are examples of techniques
`currently being studied to satisfy OBD-11 regulations:
`
`486
`
`• Catalyst monitoring: MIL lights when the HC conversion
`efficiency of the catalyst falls to below 60%
`< Diagnostic method >
`The HC conversion efficiency of the catalyst is determined
`by comparing the signals of two 0 2 sensors which are
`installed after and before the catalyst, respectively.
`• Misfire monitoring: MIL lights when a misfire damaging
`the catalyst, or exceeding 1.5 times the emission control
`level, is detected.
`< Diagnostic method >
`Misfire is determined by measuring engine speed for every
`ignition timing using a ring gear sensor.
`• Fuel system monitoring: MIL lights on detecting an
`abnormality in the fuel system which exceeds the emission
`controllevel1.5 times.
`< Diagnostic method >
`An abnormal fuel system is determined upon detecting an
`abnormal learning value of/.. control by 0 2 sensor (mixture
`is too rich or lean).
`Technological tasks include improved detection
`accuracy, development of diagnostic methods in response
`to the overall diagnostic system, and confirmation of
`diagnostic performance.
`
`Forecast of defects to directly detect a change in the
`characteristics leading to a defect- Deterioration detecting
`sensors must be developed and detection systems
`constructed in orderto detect deterioration more accurately.
`The following are examples of techniques currently being
`studied to satisfy OBD-11 regulations:
`• 0 2 sensor monitoring: MIL lights when the output voltage/
`response speed is abnormal to the extent that the
`emission control level is exceeded 1.5 times.
`<Diagnostic method>
`An abnormality is determined by the rich/lean response
`time of two 0 2 sensors and voltage.
`• Misfire monitoring: MIL lights when a misfire capable of
`damaging the catalyst or exceeding the emission control
`level1.5 times is detected.
`<Diagnostic method>
`A misfire is determined by analyzing the waveforms of the
`combustion pressure sensor (Figure 16).
`Technological tasks include the development of a new
`sensor to detect performance deterioration. The following
`themes should be studied:
`• Enlargement of the dynamic range and improvement of
`accuracy (resolution)
`• Development of ICs with an embedded deterioration
`detecting sensor.
`• Development of a sensor to store useful information
`such as sound and vibration.
`
`RESEARCH ON PROBLEM-SOLVING
`TECHNOLOGY
`
`Example of Engine Control
`• Learning Control
`Variations and deterioration of constituent parts of a
`control system are detected or predicted to make the
`necessary correction for the target value. Learning
`
`12
`
`

`

`Combustion pressur
`
`Com"'''"" t
`
`Pressure /S
`
`Te
`
`Fig. 16 Analysis of Waveforms of Combustion Pressure Sensor
`
`control is used, for example, in the following control
`functions: air-to-fuel learning control, ignition timing
`learning control, and idle revolution learning control.
`• Limp Home Function
`A very hazardous situation could be developed if the
`engine stopped due to the failure of a microcomputer
`while running on a highway, in desert area, etc. One may
`wish to go to a nearby service shop, even if the car may
`"limp," there, by controlling the car in the simplest way. A
`dual-system circuit, parts, etc. are used as a backup in
`case of the failure of a microcomputer.
`• Fail-safe Function
`Even if proper operation of the ECU is impaired by a
`failed ECU part or an abnormal environmental condition
`(lightning or other strong electric and magnetic noise), a
`serious failure or accident must be avoided as far as
`possible. The following are some examples of fail-safe
`function that are already commercially available.
`
`Future Requirements - The combination of an abrupt
`failure detection system and a conventional fail-safe system
`is quite likely to cause a major accident in an on-road
`obstacle collision prevention system. Failure forecasts
`should be reported to the driver when performance
`deterioration is detected: at the same time, the system
`functions must be maintained. To develop such a system,
`it is necessary not only to study system life control, but also
`to fully understand the process of how deteriorated
`performance develops into a major problem and to
`restructure the entire car system accordingly.
`
`487
`
`SUMMARY
`
`The Japanese automobile industry rushed to adopt
`electronics technology in orderto design electronic features
`into their products: consequently, it lacks experience in
`automotive electroics and urgently needs to further develop
`basic diagnostic technologies. To ensure the most efficient
`and effective development of automotive electronics,
`service and maintenance techniques must be improved to
`keep pace with the release of new products and systems.
`Only when parity is reached in these areas will new
`products meet customer requirements and allow automotive
`electronics to further advance to the next level of technical
`sophistication.
`
`REFERENCES
`
`(1)
`
`Toyota 1G-EU, 1G-GEU, 1G-EJ Maintenance
`Manual (March 1986).
`Sugino: Development of Diagnostic Unit, Daihatsu
`AXIS, No. 102 (1992).
`Kubozono: "Development of Car Electronics
`Diagnostic System," Mitsubishi Motors Technical
`Review, No.1 (1988).
`(4) Mazda Eunos 500 Maintenance Manual, January
`1992.
`Yamaoka: Hi-Tech Diagnostic Tester "Nissan
`CONSULT," Automobile Engineering, Vol. 39, No.8
`(July, 1990).
`(6) U.S. Patent 4694408 publication.
`
`(2)
`
`(3)
`
`(5)
`
`13
`
`

`

`{9)
`
`{8)
`
`{7) Ozawa: "Trends of Research and Development of
`Car Diagnostic Units," Automobile Engineering,
`Vol. 27, No.9 {1973).
`Yoshida: "Service Equipment and Electronics,"
`Automobile Engineering, Vol. 29, No.4 {1975).
`Sone: "Trends of Diagnostic Systems in American
`Cars," Automobile Engineering, Vol. 41, No. 2
`{1987).
`{1 0) Ezoe: "Trends of Car Diagnostic Techniques and
`Future Tasks," Automobile Engineering, Vol. 37,
`No. 10 (1983).
`{11) Bosch KTS300 catalog.
`{12) JASO Diagnostics Terminology for Vehicle
`Electronic Control Systems, The Society of
`Automotive Engineers of Japan).
`{13) Kubozono: "Electronics Diagnostic Tester,"
`Automobile Engineering, Vol. 42, No.9 {1988).
`{14) Kishi: "Application of Expert System to Engine
`Diagnostics," Automobile Engineering, Vol. 40, No.
`2 {1986).
`(15) Kitamura: "Introduction of Electronic System
`Diagnostic Tester CONSULT," Nissan Technical
`Report No. 29 (June 1991 ).
`(16) Kawazoe: "Highly Functional Diagnostics for On(cid:173)
`board Electronic Control Systems," Mazda Technical
`Report, No.9 (1991).
`(17) Abe: "Trends of Diagnostic Tools," Automobile
`Engineering, Vol. 47, No.2 (1933).
`(18) Hiwa: "Diagnostics for Vehicle Electronic System(cid:173)
`- Present State and Future Trends," Automobile
`Engineeri