Automotive Computer Controlled Systems

265 Pages·2003·7.5 MB·English

AutomotiveComputer
ControlledSystems
AutomotiveComputer
ControlledSystems
Diagnostic tools and techniques
AllanW.M.Bonnick
MPhil CEng MIMechE MIRTE
OXFORD AUCKLAND BOSTON JOHANNESBURG MELBOURNE NEWDELHI
Butterworth-Heinemann
LinacreHouse,JordanHill,OxfordOX28DP
225WildwoodAvenue,Woburn,MA01801-2041
AdivisionofReedEducationalandProfessionalPublishingLtd
Firstpublished2001
AllanBonnick,2001
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BritishLibraryCataloguinginPublicationData
Bonnick,AllanW.M.
Automotivecomputercontrolledsystems:diagnostictools
andtechniques
1. Automotivecomputers
I. Title
629.20549
ISBN0750650893
LibraryofCongressCataloguinginPublicationData
Bonnick,AllanW.M.
Automotivecomputercontrolledsystems:diagnostictoolsandtechniques/Allan
W.M.Bonnick.
p.cm.
Includesindex.
ISBN0750650893
1. Automotivecomputers.2. Automobiles–Maintenanceandrepair.I.Title.
TL272.53B66
629.207–dc21 2001018080
Typesetin11/13ptGaramondbyLaserWords,Madras,India
PrintedandboundinGreatBritain
1 Common technology .................................. 1
1.1 Common technology......................................... 1
1.2 Engine-related systems.................................... 2
1.3 Ignition systems................................................ 2
1.3.1 THE CONSTANT ENERGY IGNITION
SYSTEM .................................................................. 2
1.3.2 DIGITAL (PROGRAMMED) IGNITION
SYSTEM .................................................................. 3
1.3.3 DISTRIBUTORLESS IGNITION SYSTEM...... 6
1.3.4 OPTOELECTRONIC SENSING FOR THE
IGNITION SYSTEM ................................................. 8
1.3.5 KNOCK SENSING.......................................... 9
1.3.6 ADAPTIVE IGNITION ..................................... 9
1.4 Computer controlled petrol fuelling systems..... 10
1.4.1 SINGLE-POINT INJECTION........................... 11
1.4.2 MULTI-POINT INJECTION ............................. 13
1.5 Engine management systems (EMS)............... 17
1.5.1 EXHAUST GAS RECIRCULATION ................ 18
1.5.2 COMPUTER CONTROL OF
EVAPORATIVE EMISSIONS................................... 19
1.6 Anti-lock braking (ABS) .................................... 19
1.6.1 OPERATION OF ABS..................................... 22
1.6.2 SOME GENERAL POINTS ABOUT ABS ....... 22
1.7 Traction control................................................. 22
1.8 Stability control ................................................. 25
1.9 Air conditioning................................................. 27
1.9.1 DEALING WITH AIR CONDITIONING
REFRIGERANT ....................................................... 29
1.10 Computer controlled damping rate ................. 30
1.11 Computer controlled diesel engine
management systems ............................................ 30
1.11.1 SPILL CONTROL.......................................... 33
1.11.2 TIMING CONTROL....................................... 35
1.11.3 IDLE SPEED CONTROL .............................. 35
1.12 Summary ........................................................ 38
1.13 Review questions ........................................... 38
2 The Computer ECM .................................... 2
2.1 The fundamental parts of a computer............... 2
2.1.1 COMPUTER MEMORY .................................. 41
2.1.2 THE CLOCK ................................................... 41
2.2 A practical automotive computer system.......... 41
2.3 Principles of operation ...................................... 44
2.4 Computer data.................................................. 45
2.4.1 DATA TRANSFERS........................................ 45
2.4.2 DATA TRANSFER REQUIREMENTS ............ 46
2.5 Computer interfaces ......................................... 46
2.6 Control of output devices.................................. 47
2.7 Computer memories ......................................... 48
2.7.1 READ ONLY MEMORIES............................... 49
2.7.2 RANDOM ACCESS MEMORY....................... 50
2.7.3 OTHER TYPES OF COMPUTER
MEMORY................................................................. 50
2.8 Fault codes....................................................... 51
2.9 Adaptive operating strategy of the ECM........... 51
2.9.1 LIMITED OPERATING STRATEGY (LOS)..... 52
2.10 Networking of computers................................ 52
2.10.1 A BUS-BASED SYSTEM .............................. 52
2.10.2 STAR CONNECTED COMPUTERS............. 52
2.10.3 MESSAGES.................................................. 53
2.10.4 PROTOCOLS ............................................... 54
2.11 Vehicle network systems ................................ 55
2.11.1 THE PRINCIPLE OF A BUS-BASED
VEHICLE SYSTEM.................................................. 55
2.11.2 DATA BUSES FOR DIFFERENT
APPLICATIONS....................................................... 57
2.11.3 ENCODING SERIAL DATA .......................... 57
2.12 Prototype network systems ............................ 59
2.13 Summary ........................................................ 62
2.14 Review questions ........................................... 63
3 Self-diagnosis and fault codes.................. 3
3.1 Access to DTCs................................................ 3
3.1.1 METHOD 1: THE DASHBOARD LAMP.......... 4.
3.1.2 METHOD 2: FAULT CODES DISPLAYED
THROUGH A LOGIC PROBE OR TEST LAMP ...... 70
3.1.3 METHOD 3: FAULT CODE READERS
AND SCAN TOOLS ................................................. 70
3.2 Developments in self-diagnosis........................ 78
3.2.1 OBD I .............................................................. 79
3.2.2 OBD II ............................................................. 79
3.3 Diagnostic equipment and limitations of
DTCs ...................................................................... 3.22
3.4 Review questions ............................................. 83
4 Diagnostic tools and equipment ............... 4
4.2 Breakout boxes................................................. 94
4.1 Diagnostic tools that connect to ECM............... 4
4.3 The digital multimeter ....................................... 95
4.4 Portable flat screen oscilloscopes .................... 96
4.5 Diagnostic tool and oscilloscope combined...... 97
4.6 Pressure gauges .............................................. 99
4.6.1 VACUUM PUMPS AND GAUGES.................. 99
4.7 Calibrating test instruments.............................. 103
4.8 Location charts and wiring diagrams................ 103
4.9 Sources of diagnostic data ............................... 103
4.10 Exhaust gas emissions and emission
system testing......................................................... 4.21
4.10.1 PETROL ENGINE EMISSIONS.................... 4.21
4.10.2 DIESEL ENGINE EMISSIONS ..................... 108
4.11 Review questions ........................................... 110
5 Sensors........................................................ 5
5.1 Electromagnetic sensors .................................. 5
5.1.1 THE VARIABLE RELUCTANCE TYPE
SENSOR.................................................................. 5
5.1.2 HALL EFFECT SENSORS ............................. 116
5.2 Optical sensors................................................. 118
5.3 Combustion knock sensors .............................. 119
5.4 Variable resistance type sensors...................... 121
5.5 Temperature sensors ....................................... 124
5.6 Ride height control sensor................................ 125
5.7 Manifold absolute pressure (MAP) ................... 126
5.7.1 THE VARIABLE VOLTAGE MAP SENSOR ... 127
5.7.2 OTHER MAP SENSORS ................................ 129
5.8 Exhaust gas oxygen sensors............................ 130
5.8.1 THE VOLTAIC-TYPE EGO SENSOR............. 132
5.8.2 THE RESISTIVE-TYPE EGO SENSOR ......... 137
5.8.3 ON-BOARD MONITORING OF THE
CATALYTIC CONVERTER...................................... 138
5.9 Air flow measurement....................................... 138
5.9.1 HOT WIRE MASS AIR FLOW SENSOR
(MAF)....................................................................... 142
5.10 The practical importance of sensor
knowledge .............................................................. 144
5.11 Review questions ........................................... 144
6 Actuators..................................................... 6
6.1 Actuator operation ............................................ 6
6.2 Petrol engine fuel injectors ............................... 147
6.2.1 SINGLE POINT INJECTION........................... 147
6.2.2 MULTI-POINT PETROL INJECTION.............. 147
6.3 Testing of petrol injectors ................................. 149
6.3.1 PEAK AND HOLD........................................... 149
6.3.2 CONVENTIONAL SWITCHING TO EARTH... 150
6.3.3 PULSE WIDTH MODULATED
INJECTORS............................................................. 152
6.3.4 FURTHER INJECTOR TESTS ....................... 154
6.4 Exhaust gas recirculation ................................. 154
6.4.1 TESTING THE EGR SENSOR ....................... 155
6.5 Petrol engine idle speed control ....................... 155
6.5.1 STEPPER MOTOR-OPERATED VALVE ....... 157
6.5.2 SOLENOID-OPERATED VALVE.................... 160
6.6 Ignition system.................................................. 161
6.7 ABS actuators................................................... 161
6.8 A clamping diode.............................................. 162
6.9 Electronic unit injectors..................................... 163
6.10 Review questions ........................................... 165
7 Diagnostic techniques ............................... 7
7.1 Circuit testing.................................................... 7
7.2 Vehicle specific details ..................................... 172
7.3 The ’six-steps’ approach................................... 173
7.4 Skills required for effective diagnosis ............... 174
7.5 An approach to fault finding.............................. 175
7.6 Emissions related testing.................................. 179
7.6.1 OXYGEN SENSOR ........................................ 179
7.6.2 KNOCK SENSORS......................................... 186
7.6.3 AIR FLOW METERS....................................... 187
7.6.4 THROTTLE POSITION SWITCHES............... 190
7.6.5 A COOLANT TEMPERATURE SENSOR....... 192
7.6.6 MANIFOLD ABSOLUTE PRESSURE
SENSOR (MAP) TESTS.......................................... 195
7.7 Ignition system tests ......................................... 198
7.7.1 TESTS ON DISTRIBUTORLESS
IGNITION DIS.......................................................... 198
7.8 Diesel injection ................................................. 200
7.8.1 TESTING THE INJECTION POINT
ADVANCE................................................................ 202
7.9 Sensor tests on other systems ......................... 202
7.9.1 ABS WHEEL SPEED SENSORS ................... 203
7.9.2 TESTING THE RIDE HEIGHT CONTROL
SENSOR.................................................................. 206
7.10 Intermittent faults ............................................ 207
7.10.1 FLIGHT RECORDER (DATA LOGGER)
FUNCTION .............................................................. 208
7.11 Summary ........................................................ 209
7.12 Review questions ........................................... 210
8 Additional technology ................................ 8
8.1 Partial and absolute pressures......................... 8
8.2 The piezoelectric effect..................................... 213
8.3 Liquid crystal displays....................................... 214
8.4 Countering cross-talk........................................ 216
8.5 Logic devices.................................................... 216
8.5.1 THE RTL NOR GATE ..................................... 216
8.5.2 TRUTH TABLES............................................. 217
8.5.3 THE SR (SET, RESET) FLIP-FLOP ............... 218
8.5.4 ANALOGUE TO DIGITAL CONVERSION...... 221
8.5.5 DIGITAL TO ANALOGUE CONVERSION...... 222
8.6 OBD II............................................................... 223
8.6.1 FUEL SYSTEM LEAKAGE ............................. 224
8.6.2 SECONDARY AIR INJECTION ...................... 225
8.6.3 FREEZE FRAMES.......................................... 226
8.6.4 STANDARDIZED FAULT CODES.................. 226
8.7 Computer performance (MIPS) ........................ 227
8.8 Supplementary restraint systems (SRS) .......... 227
8.8.1 HANDLING SRS COMPONENTS .................. 230
8.9 The coded ignition key...................................... 231
8.10 Fault tracing.................................................... 232
8.11 Precautions when working with computer
controlled systems.................................................. 232
8.12 Variable capacitance sensor .......................... 233
8.13 Optoelectronics............................................... 234
8.14 Review questions ........................................... 235
Appendix ........................................................ A.1
A.1 Companies who supply equipment and
diagnostic data ....................................................... A.1
A.2 Answers to review questions............................ A.1
A.3 OBD II standard fault codes ............................. 238
Index ............................................................... 46