14 BASICS OF ELEC ELECTR TRIC ICAL AL SYST SYSTEM EMS S CHAPTER OVERVIEW This quite technical chapter forms a foundation for the electrical systems covered in Chapters 16 through 23. The first five pages of Chapter 6 can be reviewed in conjunction with this chapter.
CHAPTER OBJECTIVES Explain the basic principles of electricity. Define the terms normally used to describe electricity. electricity. Use Ohm’s law to determine voltage, current, and resistance. List the basic types of electrical circuits. Describe the differences between a series and a parallel circuit. Name the various electrical components and their uses in electrical circuits. Describe the different kinds of automotive wiring. Explain the principles of magnetism and electromagnetism electromagnetism..
INSTRUCTIONAL OUTLINE WITH TEACHING HINTS I. II.
III.
Basics of Electricity A. Flo Flow w of Ele Electr ctrici icity ty Electrical Terms A. Cir Circui cuitt Term Termino inolog logyy B. Po Powe werr So Sour urce cess C. Oh Ohm m’s La Law w D. Power Conductors and Insulators A. Cir ircu cuiits 1. Ser Series ies Cir Circui cuits ts 2. Par Parall allel el Cir Circui cuits ts 3. Seri Series-Pa es-Paralle rallell Circ Circuits uits B. Gr Grou ound ndin ing g th thee Lo Load ad Hint: Show examples of the different types of circuits and show how they differ.. Have the students practice taking voltage and resistance measurements differ with each type of circuit and compare their results to calculated values.
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Chapter 14
IV.. IV
V.
Circuit Components A. Re Ressis isto torrs 1. Fix Fixed ed Valu Valuee Resisto Resistors rs 2. Tapped or Steppe Stepped d Resisto Resistors rs 3. Vari ariabl ablee Resisto Resistors rs B. Cir Circui cuitt Prote Protecti ctive ve Devi Devices ces 1. Fuses (a) Car Cartri tridge dge (b)) Bl (b Blad adee (c)) Ce (c Cera rami micc 2. Fu Fuse se Li Link nkss 3. Ma Maxi xi-F -Fus uses es 4. Cir Circui cuitt Bre Breake akers rs 5. 4242-V Volt Sys System temss 6. Volt oltage age Lim Limite iterr C. Switches D. Relays E. Solenoids F. Capacitors G. Wiring 1. Fl Flat at Wir irin ing g 2. Pri Printe nted d Cir Circui cuits ts Hint: Show examples of each of the circuit components listed. Electromagnetism Basics A. Fun Fundam dament entals als of Magn Magneti etism sm 1. Poles 2. Fl Flux ux Fi Fiel eld d 3. Fl Flux ux De Dens nsit ityy 4. Coils B. Mag Magnet netic ic Circu Circuits its and and Reluct Reluctanc ancee C. In Indu duce ced d Vol Volta tage ge Hint: Discuss the role that magnetism plays in automotive systems.
ANSWERS TO TEXTBOOK REVIEW QUESTIONS Ohm’s law, Ohm’s law, which expresses the mathematical relationship between current, voltage, and resistance throughout a series series circuit. 2. True. The same amount of current is present throughout 3. The two types of automotive wiring are solid and stranded, with stranded wiring being the most common. 4. The four factors that determine the amount of voltage induced by a magnet are (1) a stronge strongerr magnetic field field will produce produce a stronger stronger induced voltage; voltage; (2) the faster faster the magnetic field is being cut, the stronger the induced voltage; (3) a greater number of conductors will produce a greater induced voltage; and (4) the closer th e conductors and magnetic field are to being bein g at right angles to one another, the greater the induced voltage. 5. Trimmers or tuners induction. n. 6. When a conductor cuts across a magnetic field producing voltage, it is called inductio 7. An increase in resistance in a circuit produces a reduction of current flow. flow. 1.
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Chapter 14
IV.. IV
V.
Circuit Components A. Re Ressis isto torrs 1. Fix Fixed ed Valu Valuee Resisto Resistors rs 2. Tapped or Steppe Stepped d Resisto Resistors rs 3. Vari ariabl ablee Resisto Resistors rs B. Cir Circui cuitt Prote Protecti ctive ve Devi Devices ces 1. Fuses (a) Car Cartri tridge dge (b)) Bl (b Blad adee (c)) Ce (c Cera rami micc 2. Fu Fuse se Li Link nkss 3. Ma Maxi xi-F -Fus uses es 4. Cir Circui cuitt Bre Breake akers rs 5. 4242-V Volt Sys System temss 6. Volt oltage age Lim Limite iterr C. Switches D. Relays E. Solenoids F. Capacitors G. Wiring 1. Fl Flat at Wir irin ing g 2. Pri Printe nted d Cir Circui cuits ts Hint: Show examples of each of the circuit components listed. Electromagnetism Basics A. Fun Fundam dament entals als of Magn Magneti etism sm 1. Poles 2. Fl Flux ux Fi Fiel eld d 3. Fl Flux ux De Dens nsit ityy 4. Coils B. Mag Magnet netic ic Circu Circuits its and and Reluct Reluctanc ancee C. In Indu duce ced d Vol Volta tage ge Hint: Discuss the role that magnetism plays in automotive systems.
ANSWERS TO TEXTBOOK REVIEW QUESTIONS Ohm’s law, Ohm’s law, which expresses the mathematical relationship between current, voltage, and resistance throughout a series series circuit. 2. True. The same amount of current is present throughout 3. The two types of automotive wiring are solid and stranded, with stranded wiring being the most common. 4. The four factors that determine the amount of voltage induced by a magnet are (1) a stronge strongerr magnetic field field will produce produce a stronger stronger induced voltage; voltage; (2) the faster faster the magnetic field is being cut, the stronger the induced voltage; (3) a greater number of conductors will produce a greater induced voltage; and (4) the closer th e conductors and magnetic field are to being bein g at right angles to one another, the greater the induced voltage. 5. Trimmers or tuners induction. n. 6. When a conductor cuts across a magnetic field producing voltage, it is called inductio 7. An increase in resistance in a circuit produces a reduction of current flow. flow. 1.
Basics of Electrica Electricall Syste Systems ms
8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18.
19. 20.
61
Voltage refers to electrical pressure; current refer to the amount of electron flow. False. The strength of the magnetic field at the poles of an electromagnet electromagnet increases with an increase in current, or an increase in the number of turns of wire. A switch that is identified as SPST is a single-pole, single-throw switch or, in other words, a simple on-off switch such as would be used in a simple circuit. A normally closed switch is one whose contacts are closed until acted on by an outside force such as oil pressure or movement of a lever lever.. c. Both magnetism and chemical reactions are used to produce electricity in automobiles. c. Both statements are correct. correct. A decrease decrease in resistance resistance will result in increased increased current, and current will decrease as resistance increases according to Ohm’ Ohm’ss Law. Law. A thermistor is a type of variable resistor that changes its resistance value as its temperature changes. d. Al Alll of of the the abo above ve b. The current through through each leg is different if if the resistance values are different. different. b. 4 amps. Using the product/sum formula (36/12 = 3), the total resistance is 3 ohms. So by applying Ohm’s Ohm’s law (12/3 = 4), the current total is 4 amps. a. Technician A is correct; using the reciprocal formula we find that the resistance total in the circuit is 1 ohm. Using Ohm’s law to find the current flow through the 6-ohm resistor (12/6 = 2), we find that there will be 2 amps flowing through it, not 12 amps as stated. c. The length, diameter diameter,, and temperature temperature of a wire wire affect its resistance; where where it is located does not. b. Usi Using ng the for formul mulaa P = E I , a 12-volt light bulb drawing 12 amps would have P = a power output of 144 watts, not 1 watt watt as stated. An electric motor motor with 1-ohm resistance would draw 12 amps of current ( I I = = E/R = 12/1 = 12). Using the formula P = P = E I I = = 12 12 =144, there would be a power output of 144 watts. ¥
¥
¥
ADDITIONAL TEACHING HINTS Demonstrate how to perform voltage, amperage, resistance, and frequency measurements and how to perform a voltage drop test. Examine several electrical components and explain how each works. Demonstrate the features of a typical DMM and show how and when to use each one. Demonstrate proper wire repair and terminal replacement, including soldering techniques. Show examples of high resistance connections and intermittent circuits.
ANSWERS TO TECH MANUAL REVIEW QUESTIONS 1.
2. 3. 4.
Electricity is a form of energy that is released as the electron moves from one atom to another. It is something that takes place or can take place in everything you know. It not only provides power lights, TV’s, stereos, and refrigerators, it is also the basis for the communication between our brain and the rest of our bodies. Electrical potential is the difference in electrical pressure or voltage between points in a circuit. True Zero
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Chapter 14
5. 6. 7. 8. 9. 10.
False True A maxi-fuse has values of 20 to 60 amperes, whereas mini-fuses have values of 4 to 30 amperes. Permanent magnets retain their magnetic property for a very long time. Electromagnets quickly lose their magnetism when the magnetizing force is removed. The resistance that a magnetic circuit offers to a line of flux a
15 BASICS OF ELECTRONICS
CHAPTER OVERVIEW This chapter explains the principles of operation and the components used in onboard computers and other electronic systems.
CHAPTER OBJECTIVES Describe how semiconductors, diodes, and transistors work. Explain the principles of operation for common electronic circuits. Explain the principle of multiplexing. Describe the basic function of the central processing unit (CPU). List and describe the functions of the various sensors used by computers. Describe the principle of analog and digital signals. Explain the principle of computer communications. Summarize the function of a binary code. Name the various memory systems used in automotive microprocessors. List and describe the operation of output actuators. Describe the basic electronic logic circuits.
INSTRUCTIONAL OUTLINE WITH TEACHING HINTS I.
Computers A. Semiconductors 1. N-Type Semiconductors 2. P-Type Semiconductors (a) Hole Flow (b) Semiconductor Uses 3. Diodes and Transistors (a) Diodes (b) Transistors B. Semiconductor Circuits Hint: Show various sizes and types of solid state components and describe their operation. Show several circuit boards and have the students identify as many components as they can.
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Chapter 15
II.
III.
IV.
Integrated Circuits Hint: Show a circuit board with integrated circuits. Talk about how many circuits and components may be present in one IC chip. Microprocessor Operation A. Sensors 1. Reference Voltage (Vref) Sensors (a) Variable Resistors (b) NTC-Type Thermistors (c) PTC-Type Thermistors (d) Wheatstone Bridges 2. Voltage Generating Devices (a) Magnetic Pulse Generators (b) Hall-Effect Switches B. Communication Signals 1. Communication Rates C. Logic Gates 1. NOT Gate 2. AND Gate 3. OR Gate 4. NAND and NOR Gates 5. Exclusive-OR (XOR) Gate 6. Gate Combinations (a) Decoder Circuits (b) Multiplexer (MUX) (c) Demultiplexer (DMUX) (d) RS and Clocked RS Flip-Flop Circuits (e) Registers (f) Accumulators D. Memories 1. Read-Only Memory (ROM) 2. Programmable Read-Only Memory (PROM) 3. Erasable Programmable Read-Only Memory (EPROM) 4. Electrically Erasable Programmable Read-Only Memory (EEPROM) 5. Random-Access Memory (RAM) 6. Keep-Alive Memory (KAM) 7. Nonvolatile Random-Access Memory (NVRAM) Hint: Discuss the various types of memories and their automotive applications. E. Actuators 1. Output Drivers 2. Duty-Cycle Versus Pulse Width Modulated 3. Liquid Crystal Display (LCD) 4. Vacuum Fluorescent Display (VFD) 5. Power Supply Multiplexing A. Advantages B. Types of Multiplexing C. SAE Classifications
Basics of Electronics
65
ANSWERS TO TEXTBOOK REVIEW QUESTIONS 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20.
The three main types of memory in a computer are called, ROM, RAM, and PROM. The device that stores and processes data is a microprocessor or computer. Analog signals show any change in voltage. Digital signals are typically called square wave patterns. Feedback means that data concerning the effects of the computer’s commands are fed back to the computer as an input signal. The type of memory that contains specific information about th e vehicle and can be removed and reprogrammed or replaced is called PROM. The major components of an automotive control system are (1) input, (2) processing, (3) output, and (4) storage. A diode is the simplest type of semiconductor. Pulse width is the length of time, usually measured in milliseconds, during which something is kept on. Information in ROM cannot be erased; RAM information is erased whenever the ignition switch is turned off. b. Most semiconductors are made of silicon. c. Both statements are correct. Applying voltage to the base turns on an NPN transistor, and current flows through the emitter and collector. c. Sensor input is not stored in ROM. True. c. PM generators are not semiconductors. They are constructed of a permanent magnet and windings of wire. a. A knock sensor is an example of a Wheatstone bridge. d. All of the above c. Both are examples of sensor inputs. b. Multiplexing uses bus data links, but the advantage gained is less wiring, not more, as stated. b. When a diode’s P material is connected to the positive charge in the circuit, it is forward biased, not reverse biased as stated by Technician A. Because like charges repel, the diode’s P conductive material is pushed toward the N material, and the N material is pushed toward the P, as stated by Technician B.
TECH MANUAL
The following procedure is included in Chapter 15 of the
Tech Manual:
1. Test for continuity across electronic and electrical components and circuits with an ohmmeter.
ANSWERS TO TECH MANUAL REVIEW QUESTIONS 1. 2. 3. 4. 5.
True False False False d
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Chapter 15
6. 7. 8. 9. 10.
11.
12.
13.
14. 15.
b True True False Duty cycle is a measurement of the amount of time something is on compared to the time of one cycle and is measured by a percentage. Pulse width is similar to duty cycle except that it is the exact time something is turned on and is measured in milliseconds. A multiplex wiring system uses a serial data bus that connects different computers or control modules together. The serial bus carries the communications between the computers as well as other information to all the control modules. a. fewer wires are required for each system function, which means smaller wiring harnesses b. lower cost, less weight, and improved serviceability c. elimination of the need for redundant series Class B multiplexing is medium-speed communication and is used primarily with instrument cluster, vehicle speed, and emissions data recording. Class C is high-speed communication and is used for real-time control of the power train, vehicle dynamics, and brake-by-wire. UART (universal asynchronous receiver transmitter) is a multiplexing system whereby one controller in the circuit is the master and the other controllers are slaves. The CAN (controller area network) is a high-speed serial data bus that ensures that the required real-time response it maintained. CAN assigns a unique identifier to every message.
16 GENERAL ELECTRICAL SYSTEM DIAGNOSTICS AND SERVICE
CHAPTER OVERVIEW Repairing nearly every system of a vehicle requires correctly diagnosing electrical and electronic systems. An understanding of how electrical/electronic systems work and the knowledge of how to use the various types of test equipment is essential to efficient diagnosis and repair.
CHAPTER OBJECTIVES Describe the different possible types of electrical problems. Read electrical automotive diagrams. Perform troubleshooting procedures using meters, test lights, and jumper wires. Describe how each of the major types of electrical test equipment is connected and interpreted. Explain how to use a DMM for diagnosing electrical and electronic systems. Explain how to use an oscilloscope for diagnosing electrical and electronic systems. Test common electrical components. Identify the proper procedures to safeguard electronic systems. Test common electronic components. Properly repair wiring and connectors.
INSTRUCTIONAL OUTLINE WITH TEACHING HINTS I.
II.
Electrical Problems A. Open Circuits B. Short Circuits C. High-Resistance Circuits Hint: Demonstrate each of the common circuit faults and show its effect on current flow and voltage. Electrical Wiring Diagrams Hint: Show some common wiring diagrams. Have the students identify the components by their symbols. Have students find the power and ground supply points for various circuits.
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Chapter 16
III.
IV.
V.
VI.
VII.
VIII. IX. X.
Electrical Testing Tools A. Circuit Testers B. Voltmeters C. Ohmmeters D. Ammeters E. Other Test Equipment 1. Jumper wires 2. Volt/Ampere Tester 3. Scan Tools 4. Computer Memory Saver Using Multimeters A. Graphing Multimeters Hint: Show a multimeter and describe its features. Using Lab Scopes A. Analog versus Digital Scopes B. Waveforms C. Scope Controls Testing Basic Electrical Components A. Protection Devices 1. Fuses 2. Fuse Links 3. Maxi-Fuses 4. Circuit Breakers 5. Thermistors B. Switches C. Relays D. Stepped Resistors E. Variable Resistors F. Wiring G. Printed Circuits Hint: Display several different examples of each of the basic electrical components. Troubleshooting Circuits A. Testing for Opens B. Testing for Shorts C. Testing For Unwanted Resistance Hint: Demonstrate how each of the preceding conditions can be diagnosed using several types of test equipment such as multimeters and test lights. Protecting Electronic Systems Testing Electronic Circuits and Systems Connector and Wire Repairs
ANSWERS TO TEXTBOOK REVIEW QUESTIONS The circuit will not have current flowing through it and behave as though it were off. 2. When there is unwanted resistance in a circuit, current flow will be lower than normal, and the components in the circuit will be unable to operate normally. 1.
General Electrical System Diagnostics and Service
3.
4. 5. 6. 7. 8. 9. 10. 11.
12.
13. 14.
15.
16.
17. 18. 19.
20.
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To test a diode using a multimeter you would first isolate the diode from the rest of the circuit. Set the meter to the diode check function if equipped or use the ohmmeter function. Connect the meter’s leads across the diode. Observe the reading on the meter. Then reverse the leads and observe the reading on the meter. The resistance in one direction should be very high or infinite, and in the other direction the resistance should be very close to zero. A diode with high resistance in both directions is open, and one with low resistance in both directions is shorted. An ammeter is always connected in series with the circuit, while a voltmeter is connected in parallel with the circuit. b. A power wire that is contacting the chassis would be an example of a short to ground, not high resistance. False. A zero reading on an ohmmeter means that there is a complete circuit between the test leads with zero resistance. True. The voltage drop across wiring, connectors, and other conductors should not exceed 10% of source voltage. c. Either meter may be used to test circuit protection devices. Electrical wiring should be repaired using rosin-core solder. d. Use the horizontal control. The horizontal scale measures time. b. A test light is used to identify shorted or open circuits, not to detect resistance as stated. A jumper wire can be used to bypass faulty components such as circuit breakers or relays, or to apply a known good voltage or ground supply to test a light. c. Both technicians are correct. A wire-to-wire short causes increased current flow, resulting in burned insulation and melted connectors. Common connectors shared by the two affected circuits are a possible location where one circuit may be shorted to another. d. Either an open circuit or high resistance problems may cause a load device not to work. b. A voltmeter is used to measure the amount of voltage dropped across a portion of a circuit. A portion of the circuit with very little resistance will drop very little of available voltage. c. A voltmeter can be used to check a switch by testing for the presence of voltage on each side of the switch, or by performing a voltage drop test across the switch. Comparing resistance across the switch terminals as the switch is opened and closed may also be used to check it. d. An open circuit causes a complete loss of current flow through the circuit; without current flow, there will be no voltage drops across the various loads. High-resistance problems cause decreased current flow, not increased flow as stated by Technician B. True. Oils from your skin can cause corrosion of electrical connectors. d. Neither technician is correct. The best way to check a wire is to measure the voltage drop across it. a. A rheostat may be tested using a voltmeter to observe the output voltage; look for a smooth change as the control is moved. A potentiometer is another type of variable resistor and is tested with a voltmeter or an ohmmeter, not a test light as stated by Technician B. d. Neither technician is correct. An open circuit will have infinite resistance; a component that is shorted will have less than specified resistance.
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Chapter 16
TECH MANUAL
The following procedures are included in Chapter 16 of the Tech Manual: 1. 2. 3. 4. 5. 6.
Checking continuity in a current with a test light. Testing for voltage with a DMM. Testing voltage drop across connectors. Inspecting and testing fuses, fusible links, and circuit breakers. Part identification on a wiring diagram. Using a DSO on sensors and switches.
ADDITIONAL TEACHING HINTS Show the meters and test equipment the students will be using and demonstrate their features and proper use. Show an example of an electronic component such as a computer or similar control module that has failed due to using the wrong test equipment or due to static electricity. Caution the students on how to avoid such damage. Provide a collection of known good and known bad components and have the students practice testing them. Demonstrate the use of solder and shrink tubing to perform wiring repairs. Assign the students a project using solder to demonstrate their skill. Demonstrate the use of wiring diagrams. Explain the common symbols. Assign a lab project requiring the students to locate and identify power and ground sources and control circuits. Construct a parts identification board with examples of common electronic components. Test the students on their ability to identify and test each component.
ANSWERS TO TECH MANUAL REVIEW QUESTIONS 1. 2. 3. 4.
5. 6. 7. 8. 9. 10.
False Voltage is electrical pressure (volts) and current is electron flow (amperes). a A high-impedance digital multimeter must be used to test the voltage of some components and systems such as an oxygen (O 2) sensor. The high-impedance meter usually has at least 10 megohms of internal resistance. True True c c c True
17 BATTERIES: THEORY, DIAGNOSIS, AND SERVICE CHAPTER OVERVIEW Different types of batteries are described in this chapter. Cleaning, servicing, and charging procedures are explained.
CHAPTER OBJECTIVES Explain the purpose of a battery. Describe the basic parts of an automotive battery. Compare conventional and maintenance-free batteries. Explain the chemical reaction that occurs to produce current in a battery. Describe the differences, advantages, and disadvantages of the different types of batteries. Describe the different types of battery terminals used. Describe the different types of ratings used with batteries. Explain the effects of temperature on battery output. Demonstrate all safety precautions and rules associated with servicing batteries. Perform a visual inspection of a battery. Test a conventional battery’s specific gravity. Perform open circuit tests. Test the capacity and conductance of a battery. Correctly slow- and fast-charge a battery. Jump-start a vehicle by using a booster battery and jumper cables. Remove, clean, and reinstall a battery properly.
INSTRUCTIONAL OUTLINE WITH TEACHING HINTS I.
Battery Construction A. Elements and Cells B. Discharging and Charging C. Casing Design D. Terminals Hint: If possible, obtain a battery that has exploded to use as an object lesson. Show the students the consequences of careless battery service. Show how the cells are constructed and connected to each other.
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Chapter 17
II.
III.
IV. V.
VI. VII.
VIII. IX. X. XI.
XII. XIII. XIV.
Battery Designs A. Maintenance-Free and Low-Maintenance Batteries B. Hybrid Batteries C. Recombination Batteries D. Absorbed Glass Mat Batteries Battery Hardware A. Battery Cables B. Battery Hold-Downs C. Heat Shields Battery Voltage and Capacity Battery Rating Methods A. Reserve Capacity B. Ampere-Hour Rating 1. Watt-Hour Rating C. Cold Cranking 1. Cranking Amp Rating Battery Size Selection Factors Affecting Battery Life A. Improper Electrolyte Levels B. Temperature C. Corrosion D. Overcharging E. Undercharging/Sulfation F. Poor Mounting G. Cycling Safety Procedures Routine Inspections Routine Cleaning Battery Testing A. Specific Gravity Tests 1. Temperature Correction 2. Interpreting Results B. Built-in Hydrometer C. Open Circuit Voltage Test D. Battery Leakage Test E. Battery Drain Test F. Capacity Test 1. Interpreting Results G. Battery Capacitance Test Battery Charging Recycling Batteries Jump-Starting
ANSWERS TO TEXTBOOK REVIEW QUESTIONS 1.
A parasitic load is an electrical load that drains the battery while the ignition is off. Often these drains are intended to maintain computer memories or to preserve such things as clock settings and radio presets.
Batteries: Theory, Diagnosis, and Service
2. 3.
4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15.
16. 17. 18.
19. 20.
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The capacity of a battery is determined by factors such as its cell size, type of electrolyte, and type of plate materials. To perform a battery leakage test, set a voltmeter on a low DC volt range. Connect the negative test lead to the battery’s negative terminal. Then move the meter’s positive test lead across the top and sides of the battery case. If some voltage is read on the meter, current is leaking out of the battery’s cells. False. A new, fully charged battery should have a high, not a low, conductance reading. Battery corrosion is commonly caused by spilled electrolyte and electrolyte condensation from gassing . A hybrid battery is also called a deep-cycling battery. Gassing occurs in a battery during charging when the water in the electrolyte is converted into hydrogen and oxygen gases. The factors that can shorten a battery’s life are improper electrolyte levels, temperature, corrosion, overcharging, undercharging/sulfation, poor mounting, and cycling. 12.6 volts Specific gravity is the weight of a given volume of liquid divided by the weight of an equal volume of water. d. All of the above. c. Both technicians are correct. Larger batteries have larger capacities, and the BCI number identifies a battery’s features. True. Batteries are recycled more often than other items. c. Both technicians are correct. Voltage readings from an open circuit voltage test are an indication of a battery’s state of charge. If a battery fails a load test but the voltage rises above 12.4 volts when the load is removed, the battery is able to hold a charge but has insufficient cold cranking capacity and should be replaced. c. Both technicians are correct. Use baking soda to clean a battery and neutralize corrosion. d. Install a memory saver to preserve such things as computer memories and driver presets of accessories like radios and clocks. d. Neither technician is correct. The reserve capacity is the time in minutes a battery can supply 25 amps without falling below 10.5 volts at 80°F (26.6°C), and the amperehour rating is the amount of steady current a fully charged battery can discharge for twenty hours at 80°F (26.6°C). c. Batteries convert chemical energy into electrical energy and are used in fuel cell vehicles to power some of the systems such as power steering. a. Use a battery strap to safely lift a battery. Always remove the ground cable first, not the positive cable as stated by Technician B.
TECH MANUAL
The following procedures are included in Chapter 17 of the
Tech Manual:
1. Removing, cleaning, and replacing a battery. 2. Inspecting a battery for condition, state of charge, and capacity. 3. Charging a maintenance-free battery.
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Chapter 17
ADDITIONAL TEACHING HINTS Demonstrate a visual inspection of a battery. Demonstrate a hydrometer test for specific gravity in a maintenance type battery. Demonstrate an open circuit voltage test. Demonstrate a capacity (load) test with a VAT. Demonstrate proper slow and fast charging of a battery. Demonstrate proper jump-start procedures with battery cables and a booster battery (or between vehicles).
ANSWERS TO TECH MANUAL REVIEW QUESTIONS 1. 2. 3. 4. 5. 6. 7. 8. 9. 10.
A parasitic load is a load that draws current from the battery when the engine is off. Open-circuit battery voltage is the amount of voltage present across the battery terminals when the engine is off and there is no load on the battery. c True False explode negative baking soda and warm water load The battery capacity test measures the battery’s ability to provide a specific amount of current for a specific amount of time.
18 STARTING SYSTEMS
CHAPTER OVERVIEW This chapter describes the starting system and explains its service and repair.
CHAPTER OBJECTIVES Explain the purpose of the starting system. List the components of the starting system, starter circuit, and control circuit. Explain the different types of magnetic switches and starter drive mechanisms. Explain how a starter motor operates. Describe the operation of the different types of starter motors. Perform basic tests to determine the problem areas in a starting system. Perform and accurately interpret the results of a starter draw test. Disassemble, clean, inspect, repair, and reassemble a starter motor.
INSTRUCTIONAL OUTLINE WITH TEACHING HINTS I.
Starting System—Design and Components A. Starter Circuit 1. Battery and Cables 2. Magnetic Switches (a) Solenoid (b) Starter Relay 3. Starter Motor (a) Operating Principle 4. Starter Motor Drive Mechanisms (a) Positive Engagement Moveable Pole Shoe Drive (b) Solenoid-Actuated Gear Reduction Drive 5. Permanent Magnet Starter Motors 6. Starter Drive (a) Overrunning Clutch
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Chapter 18
II. III.
IV.
Control Circuit A. Starter Safety Switch Starting System Testing A. Preliminary Checks B. Safety Precautions C. Troubleshooting Procedures D. Starter Solenoid Problems E. Starting Safety Switches F. Battery Load Test G. Cranking Voltage Test 1. Test Conclusions H. Cranking Current Test I. Insulated Circuit Resistance Test 1. Test Conclusions J. Starter Relay Bypass Test 1. Test Conclusions K. Ground Circuit Resistance Test 1. Test Conclusions L. Voltage Drop Test of the Control Circuit 1. Test Conclusions M. Test Starter Drive Components 1. Test Conclusions N. Removing the Starter Motor O. Free Speed (No-Load) Test Starter Motor Service A. Starter Motor Component Tests 1. Field Coil Tests 2. Armature Tests 3. Brush Inspection 4. Bearings and Bushings 5. Starter Drives and Clutches B. Starter Motor Reassembly
ANSWERS TO TEXTBOOK REVIEW QUESTIONS 1.
2. 3. 4. 5. 6. 7.
A starter requires a large amount of current for proper operation. The battery plus its cables and connections must all be in good condition for the starter to operate normally. b. The starting safety switch is part of the control circuit, not part of the high-current circuit. a. Corroded battery cables have too much voltage drop and thus reduce available voltage for the starter. c. A ballast resistor is sometimes used in ignition circuits. b and d. Both the insulated circuit and the ground circuit should be checked for high resistance in the battery cables. a. If the solenoid clicks while trying to crank the engine, the neutral safety switch is closed and would not be a probable cause of the problem. a. There should be a minimum of 9.6 volts during cranking.
Starting Systems
8.
9.
10. 11. 12. 13.
14. 15. 16. 17. 18. 19. 20.
77
b. A lower than average cranking current is usually the result of high resistance, and the battery cables, connections, and grounds should be checked first. A bad starter is frequently indicated by a higher, not a lower, cranking current. a. A starter control circuit test could uncover high resistance in the solenoid switch circuit. The starter brushes, battery cables, and armature windings are tested using other tests. c. Both technicians are correct. Corroded connections and overly advanced ignition timing can cause the engine to crank slowly. d. All of the above. c. Both technicians are correct. Both tests can be used when checking an armature. d. Neither technician is correct. If clearance is excessive, the starter will produce a high-pitched whine while cranking, not after the engine starts as stated by Technician A. If clearance is insufficient, there will be a high-pitched whine after the engine starts, not while cranking as stated by Technician B. True. Many bearings are held in place with a retainer, while bushings are typically pressed into their bore. b. High resistance causes less current draw, not more as stated. c. Both technicians are correct. An ohmmeter is used to test field coils for open circuits and shorts to ground as described by both technicians. a. The overrunning clutch prevents the engine from turning the armature after it starts. The part of the armature that the brushes ride on is called the commutator . c. Both technicians are correct. Either a relay, a solenoid, or both may be used to complete the circuit from the battery to the starter motor. a. Measuring voltage drop is the most accurate method for measuring resistance in cables.
TECH MANUAL
The following procedures are included in Chapter 18 of the
Tech Manual :
1. Removing, inspecting, and replacing a starter motor. 2. Testing the starter and starter circuit. 3. Control circuit test.
ADDITIONAL TEACHING HINTS Demonstrate the basic tests for determining problem areas in a starting system. Demonstrate and accurately interpret the results of a current draw test. Demonstrate and accurately interpret the results of voltage drop tests on the insulated and ground circuits. Demonstrate starter bench tests and interpret the results. Disassemble, clean, inspect, repair, and reassemble a starter motor.
78
Chapter 18
ANSWERS TO TECH MANUAL REVIEW QUESTIONS 1. 2. 3. 4. 5. 6. 7. 8.
9. 10.
True c False True c d b a. Starter motor b. Starter relay c. Starter solenoid d. Starter drive A typical starter motor is grounded through its mounting on the engine and/or transmission. The neutral safety switch allows the starter motor to be used only when the vehicle shift lever is in NEUTRAL or PARK.
19 CHARGING SYSTEMS
CHAPTER OVERVIEW This chapter describes the design of and the components included in the charging system. Testing the charging system is explained, with emphasis on AC generators.
CHAPTER OBJECTIVES Explain the purpose of the charging system. Identify the major components of the charging system. Explain the purposes of the major parts of an AC generator. Explain half- and full-wave rectification and how they relate to AC generator operation. Identify the different types of AC voltage regulators. Describe the two types of stator windings. Explain the features enabled by the use of a starter/generator unit. Perform charging system inspection and testing procedures using electrical test equipment.
INSTRUCTIONAL OUTLINE WITH TEACHING HINTS I.
II.
Alternating Current Charging Systems A. AC Generator Construction 1. Rotor 2. Slip Rings and Brushes 3. Stator 4. End Frame Assembly 5. Cooling Fans 6. Liquid Cooled Generators AC Generator Operation A. DC Rectification 1. Half Wave Rectification 2. Full Wave Rectification B. Voltage Regulation C. Field Circuits
79
80
Chapter 19
III.
IV.
V.
VI.
D. Electronic Regulators 1. Integrated Circuit Voltage Regulators 2. Fail-Safe Circuits E. Computer Regulation F. Indicators 1. Indicator Light 2. Meters New Developments A. 42-Volt Generators B. Starter/Generators C. Hybrid Vehicles Hint: Discuss how AC power generation will be important as hybrid vehicles become more common. Preliminary Checks A. Safety Precautions B. Inspection General Testing Procedures A. Regulator Tests B. Voltage Output Test C. Current Output Test D. Field Current Check E. Diode Checks F. Oscilloscope Checks G. Circuit and Ground Resistance AC Generator Service
ANSWERS TO TEXTBOOK REVIEW QUESTIONS 1. 2. 3. 4. 5. 6.
7. 8. 9. 10.
11. 12.
True. A faulty voltage regulator could cause each of these conditions. A voltage regulator controls the voltage output of the AC generator by controlling the current to the rotor. To protect electronic circuits, some voltage regulators have a fail-safe circuit built into them. The diode trio rectifies AC voltage that has been produced in the stator into DC so that it can be used to create the magnetic field in the field coil of the rotor. The voltage regulator regulates the voltage output of an AC generator by controlling the amount of current through the rotor, which changes its magnetic field strength. a. The waveform produced by an AC generator is called a sine wave. The waveform produced after the output moves through the diodes is not a straight line, but a rippled line whose shape resembles the rounded tops of a picket fence. The output would be reduced by about a third. d. Neither technician is correct. Meter readings from either an ammeter or a voltmeter indicate the condition of the charging system, not the battery. b. An AC generator b. The rotor is a rotating magnetic field consisting of a field coil around an iron core and two sets of pole pieces. As current flows through the coil, the core is magnetized and the pole pieces assume the polarity of the end of the core that they touch. a. A wye winding is commonly used in automotive applications where a higher charging rate at lower engine speeds is desired. d. All of the above
Charging Systems
13. 14. 15.
16. 17. 18. 19. 20.
81
c. AC current is rectified into DC through the use of diodes. d. All of the above b. When computer modules control voltage regulation circuits, they pulse current flow through the field windings, varying the amount of on time to achieve precise voltage regulation. c. Both tests are used to check output. c. Both technicians are correct. Many charging systems feature internally regulated AC generators with ground-side, A-type voltage regulation. a. If there is no output until the AC generator is full-fielded, the voltage regulator is faulty. One or more leaking diodes would reduce output. a. An AC generator output pattern resembles the rounded top of a picket fence as viewed by an oscilloscope, not a square wave pattern as stated by Technician B. c. If a voltage drop of over 0.5 volt is found in either circuit, there is high resistance in that circuit.
TECH MANUAL
The following procedures are included in Chapter 19 of the 1. 2. 3. 4. 5. 6.
Tech Manual:
Visually inspecting the charging system. Inspecting, replacing, and adjusting drive belts and pulleys. Removing and replacing an AC generator. Testing the charging system. Disassembling and assembling an AC generator. Inspecting, cleaning, and testing AC generator components.
ADDITIONAL TEACHING HINTS Perform charging system inspection and testing procedures using electrical test equipment. Disassemble an early-model AC generator and test all of the individual components. Disassemble a late-model AC generator and compare its components with the previous model. Demonstrate how a loose belt can affect AC generator output.
ANSWERS TO TECH MANUAL REVIEW QUESTIONS 1. With an ohmmeter 2. Electronic components 3. Shorts, opens, and grounds 4. 5. 6. 7. 8. 9. 10.
Disconnect, negative cable Decreases output True c b True Shorts, opens, and grounds
20 LIGHTING SYSTEMS
CHAPTER OVERVIEW Lighting systems provide both safety and convenience to the motorist. Understanding how these circuits operate is essential to being able to maintain them. This chapter introduces the use of schematic diagrams to aid in diagnosis and service.
CHAPTER OBJECTIVES Explain the operating principles of the various lighting systems. Describe the different types of headlights and how they are controlled. Understand the functions of turn, stop, and hazard warning lights. Know how backup lights operate. Replace headlights and other burned-out bulbs. Explain how to aim headlights. Explain the purpose of auxiliary automotive lighting. Describe the operation and construction of the various automotive lamps. Diagnose lighting problems.
INSTRUCTIONAL OUTLINE WITH TEACHING HINTS I. II.
82
Lamps Headlights A. Sealed-Beam Headlights B. Composite Headlights C. High Intensity Discharge (HID) Headlamps 1. Bi-Xenon Lights Hint: Show examples of different types of headlamps and compare the merits of each. D. Headlight Switches 1. Dimmer Switches E. Headlight Circuits F. Daytime Running Lights G. Concealed Headlights
Lighting Systems
III.
IV.
V.
VI.
VII.
83
H. Flash to Pass I. Automatic Light Systems J. Adaptive Headlights Headlight Service A. Headlight Replacement B. Headlight Adjustments 1. Autoleveling Headlamps Interior Light Assemblies A. Engine Compartment Light B. Glove Box Light C. Luggage Compartment Light D. Trunk Lid Light E. Vanity Lights F. Courtesy Lights G. Illuminated Entry System Rear Exterior Light Assemblies A. Turn, Stop, and Hazard Warning Light Systems B. Flashers C. Brake Lights D. LED Lights E. Adaptive Brake Lights F. Backup Lights Light Bulbs A. Other Bulbs B. Auxiliary Lights 1. Driving Lights 2. Fog Lights Lighting Maintenance Hint: Have students list the various lighting systems used on their family vehicles.
ANSWERS TO TEXTBOOK REVIEW QUESTIONS 1. 2.
3. 4. 5. 6.
7. 8. 9.
The pull-out design, push-button design, and turn-signal-mounted rotary switch The taillight assembly is activated under the following conditions: (1) when the brake pedal is depressed, (2) when the turn signals are activated, (3) when the hazard lights are activated, and (4) when the headlights or park lights are on. False. HID lights produce a recognizable blue-white colored light and significantly less heat, allowing more flexibility in body designs for improved aerodynamics. Most headlamps either have a replaceable light bulb or they are sealed beams, which must be replaced as a unit. True c. Both technicians are correct. When one headlamp does not work, the problem is often a burned out bulb; check for the presence of voltage, and if voltage is present, replace the bulb. d. An underhood lamp is often controlled by a mercury switch. b. The rear light assembly does not contain the license plate light or rear side marker lights. a. The flash-to-pass feature illuminates the headlights even when the switch is in the off position.
84
Chapter 20
10. 11. 12. 13.
14. 15. 16.
17.
18. 19. 20.
a. Before adjusting the headlights, check the condition of the springs and shocks, and make sure the fuel tank is at least half full, not full as stated by Technician B. The dimmer switch provides a means for the driver to select between high- and lowbeam headlamp operation. a. Composite lights have a replaceable bulb, but a cracked or broken lens will not prevent operation as stated by Technician B. c. Both technicians are correct. When the brake pedal is partially depressed, the brake lights should illuminate; a vehicle equipped with adaptive brake lights will illuminate the standard brake lights during moderate braking, and under intense or ABS controlled braking additional lamps are illuminated. c. The stop light switch is normally mounted on the brake pedal arm. a. LEDs achieve their full output in less than 1 millisecond, not 200 milliseconds as stated. c. Both technicians are correct. A cracked sealed beam must remain an airtight assembly. Headlamps with halogen bulbs are sometimes vented, so some cracking and breaking of the housing will not prevent the halogen bulb from working. c. Both technicians are correct. A standard flasher may cause the remaining lights on one side of the vehicle to flash more slowly when one is burned out; and if the vehicle is equipped with an electronic flasher, the remaining bulb will flash faster when there is one burned out bulb. c. Both technicians are correct. The use of a circuit breaker to protect the headlight circuit allows for illumination of the headlights part of the time when there is a problem. High-intensity discharge (HID) lights do not have a filament; instead, an electric arc is created between two electrodes that excite a gas, such as xenon, inside the headlamp.
TECH MANUAL
The following procedures are included in Chapter 20 of the Tech Manual: 1. Inspecting and testing a headlight switch. 2. Aiming headlights. 3. Adjusting or replacing a stop light switch.
ADDITIONAL TEACHING HINTS Demonstrate headlight adjustments required by state and/or federal laws. Have students remove all the bulbs on a shop car and catalog them. Demonstrate how to troubleshoot a lighting system using an electrical schematic.
ANSWERS TO TECH MANUAL REVIEW QUESTIONS 1. 2.
Turn signals, headlight flashers, headlight low/high beam control, windshield wipers and washer, horn High-intensity discharge bulbs, sealed beams, halogen bulbs, and composite bulbs
Lighting Systems
3. 4. 5. 6. 7. 8. 9. 10.
Vibration To dim instrument lights, turn on interior light. c c True Six total, one for each filament plus a common ground at each side Two b
85
21 ELECTRICAL INSTRUMENTATION
CHAPTER OVERVIEW This chapter introduces the various gauges and warning devices found in the instrument cluster.
CHAPTER OBJECTIVES Describe the two types of instrument panel displays. Know the purpose of the various gauges used in today’s vehicles and how they function. Describe the operation of the common types of gauges found in an instrument cluster. List and explain the function of the various indicators found on today’s vehicles. List and explain the function of the various warning devices found on today’s vehicles. Explain the basics for diagnosing a gauge or warning circuit.
INSTRUCTIONAL OUTLINE WITH TEACHING HINTS I.
II.
III.
86
Instrument Panels A. Displays B. Light-Emitting Diode (LED) C. Liquid Crystal Diode (LCD) D. Vacuum Fluorescent Instrument Gauges A. Magnetic Gauges B. Thermal or Bimetallic Gauge C. Diagnosis Hint: Remove the cover so that the working parts of various types of gauges may be observed. Explain the operating principles of each type. Basic Information Gauges A. Speedometer
Electrical Instrumentation
IV.
V.
VI.
B. Odometer C. Oil Pressure Gauge 1. Diagnosis D. Coolant Temperature Gauge 1. Diagnosis E. Fuel Level Gauge F. Tachometer G. Charging Gauges H. Other Gauges 1. Fuel Consumption Gauge 2. Service Interval Display Indicators and Warning Devices A. Light Indicators and Warnings 1. Air Bag Readiness Light 2. Fasten Belts Indicator 3. Tire Pressure Monitor 4. Lamp-Out Warning Light 5. Brake Warning Light 6. Brake Pad Indicator 7. Parking Brake Warning Lamp 8. Brake Fluid Level Warning Light 9. Low Fuel Warning Light 10. Check Engine Warning Light 11. Check Filler Cap 12. Door Ajar Warning Light 13. Add Washer Fluid Lamp 14. Add Coolant Lamp 15. Antilock Light 16. Traction/Stability Control Lamp 17. Oil Pressure Indicator Light 18. Charge Indicator Light 19. Transmission Indicator 20. Drive Indicator Light 21. Air Suspension Light 22. Fog Light Indicator 23. High-Beam Light 24. Left and Right Turn Indicators 25. Stop Light Warning Light 26. Cruise Control Light 27. Rear (or Front) Defrost Indicator Light B. Sound Warning Devices 1. Park Distance Control (PDC) C. Graphic Displays Driver Information Centers A. Heads-Up Display B. Steering Wheel Touch Controls C. iDrive General Diagnosis and Testing A. Body Control Modules
87
88
Chapter 21
ANSWERS TO TEXTBOOK REVIEW QUESTIONS 1. 2. 3.
4. 5. 6.
7.
8. 9. 10.
11. 12. 13. 14. 15.
16. 17.
18. 19. 20.
False. The heads-up display compliments, rather than replaces, instrument panel displays. The instrument voltage regulator (IVR) stabilizes and limits voltage to provide for more accurate instrument operation. A magnetic-type ammeter has a permanent magnet that holds a ferrous needle centered. A coil of wire, called an armature, is wrapped around the base of the needle near the pivot point. Current flows through a conductor underneath this armature when the charging system is operating. This current induces magnetism in the armature, which either attracts or repels the permanent magnet, causing the needle to swing either left or right. Engine speed is indicated by the tachometer. The two types of instrument panel displays are analog and digital. An anti-slosh/low fuel warning (LFW) module in the fuel tank reduces needle fluctuation caused by the motion of the fuel in the tank and also provides a warning when fuel level is about 1/8 full. A coolant temperature sensor is tested by measuring resistance between its terminal and ground. It should change in response to changing engine temperature, and the results should be within specifications. d. The indicator needle of a cable-driven speedometer is held in the zero position by a hairspring. b. An open ground wire would case a total failure of the gauges, not an intermittent problem. c. Both technicians are correct. The service interval display is based on more than distance traveled. Driving style and previous operating conditions are also included in its calculations. c. Both technicians are correct. These are among the tests that should be conducted when all of the gauges are malfunctioning. b. Low oil pressure would illuminate the oil light and not the check engine light, as oil pressure is generally not monitored by the computer system. Oil pressure gauges typically use a piezoresistive sensor in the sending unit. Indicator lamps are used to indicate when something is turned on; warning lights are used to notify the driver that something in the system is not functioning properly. True. The traction/stability control lamp is yellow when the system is actively regulating drive torque and braking force and red when there is a problem with the system. b. Accumulated mileage is stored in nonvolatile ROM so that the mileage value is retained even when the battery is disconnected. a. A pressure-actuated switch in the sending unit controls the oil pressure light. It provides a ground when there is no oil pressure. It opens when there is sufficient oil pressure. A ground in the circuit between the indicator light and the pressure switch would turn the light on. An open circuit would turn the light off. a. Digital speedometers receive input from the vehicle speed sensor, not the throttle position sensor. d. The module senses a decreased, not an increased, voltage signal when one bulb is burned out. a. When there is a corroded connection to the instrument cluster it could cause all of the gauges to read too low. An open in the IVR would more likely cause the gauges that are dependent on it for their voltage source to not operate at all.
Electrical Instrumentation
89
TECH MANUAL
The following procedure is included in Chapter 21 of the
Tech Manual:
1. Removing, checking, and replacing a temperature sending unit.
ANSWERS TO TECH MANUAL REVIEW QUESTIONS LED LCD c. vacuum fluorescent IVR is used to stabilize and limit voltage for accurate instrument operation. a. electrical b. mechanical ROM Federal law requires that the same odometer reading be installed on the new unit when replacing the old unit. The piezoresistive sensor is threaded into the oil delivery passage of the engine. The pressure exerted by the oil causes the flexible diaphragm to move. This movement is transferred to a contact arm that slides down the resistor. The position of the sliding contact on the arm in relation to the resistance coil determines the resistance value and the amount of current flow through the gauge to ground. PCM or BCM Vehicle speed, turn-signal indicators, low fuel warning, and high beam indicator Fuses, indicator bulbs, detector switches, sender unit, IVR, and gauges The scan tool has the ability to communicate with these areas and supply the technician with information (data) to aid in problem diagnosis.
1. a. b. 2. 3. 4. 5. 6.
7. 8. 9. 10.
22 ELECTRICAL ACCESSORIES
CHAPTER OVERVIEW This chapter describes the different accessories such as power door locks, keyless entry systems, power windows, power seats, security systems, and other basic systems such as the windshield wipers/washers and defrosters. In order to understand these systems it is also necessary to be familiar with self-diagnostic computer controlled systems such as body control modules.
CHAPTER OBJECTIVES Know the basic operation of electric windshield wiper and washer systems. Explain the operation of power door locks, power windows, and power seats. Determine how well the defroster system performs. Identify the components of typical radio and audio systems. Understand how cruise or speed control operates and the differences of various systems. Describe the operation of keyless entry systems. Identify the various security disabling devices. Understand the operation of the various security alarms.
INSTRUCTIONAL OUTLINE WITH TEACHING HINTS Body Control Modules A. Trouble Codes B. Entering Diagnostics Hint: Display printouts of several diagnostic trouble codes (DTCs) and discuss possible causes. II. Windshield Wiper/Washer Systems A. Permanent Magnet Motor Circuits B. Electromagnetic Field Motor Circuits 1. Three-Speed Motors 2. Windshield Wiper Linkage and Blades. 3. Rear Window Wiper/Washer System I.
90
Electrical Accessories
III.
IV.
V.
VI.
VII.
VIII.
IX. X. XI.
C. Intermittent Wiper Systems 1. Rain-Sensing Wipers 2. Speed-Sensitive Wipers D. Windshield Washers E. Wiper System Service F. Washer System Service Horns/Clocks/Cigarette Lighter Systems A. Horns B. Clock C. Cigarette Lighter Cruise (Speed) Control Systems A. Vacuum Systems B. Electronic Cruise Control Systems C. Adaptive Cruise Control D. Cruise Control System Service Hint: Discuss the advantages of using cruise control while driving; tell the additional features of adaptive or smart cruise systems. Sound Systems A. Antenna 1. Power Antennas B. Satellite Radio C. Diagnosis Power Lock Systems A. Power Trunk Release B. Diagnosis Power Windows A. Circuit Operation 1. Obstacle-Sensing Windows B. Diagnosis Power Seats A. Diagnosis B. Other Seat Options 1. Temperature-Controlled Seats 2. Power Lumbar Supports 3. Memory Seats 4. Adaptive and Active Seating 5. Massaging Seats Power Mirror System A. Inside Mirrors Rear-Window Defrosters and Heated Mirror Systems A. Diagnosis Other Electronic Equipment A. Adjustable Pedals B. Heated Windshields C. Moon (Sun) Roof System 1. Solar Sunroof D. Cellular Phones E. Night Vision F. Navigation Systems
91
92
Chapter 22
XII.
G. Vehicle Tracking Systems H. Voice Activation System Security and Antitheft Devices A. Locks and Keys B. Passkey Systems 1. Passwords C. Keyless Entry Systems D. Alarm Systems Hint: If possible, have someone bring a car that is loaded with accessories that the students can familiarize themselves with. Discuss the proliferation of accessories and features made possible through electronics.
ANSWERS TO TEXTBOOK REVIEW QUESTIONS The primary purpose of adaptive cruise control is to not only maintain a desired speed, but also to maintain a desired safe distance from the vehicle in front of you in your lane. 2. An amplifier increases the volume of sound without distorting it. 3. When none of the grids in a rear window defogger operate, check the power and ground circuits to and from the grid. 4. Intermittent wipers are made possible through the use of an intermittent wiper module. It contains a timer unit that triggers an electronic switch to close the circuit for the governor relay, which, in turn, closes the circuit to the low-speed brush. This sequence causes the wipers to complete one sweep, after which time the park switch opens leaving the blades in the park position. The delay between sweeps is determined by the amount of resistance the driver selects by rotating a potentiometer control. The module contains a capacitor, which is charged through this potentiometer. The longer it takes to saturate the capacitor, the longer the delay between wiper sweeps. As more resistance is added by rotating the potentiometer, more time is needed to saturate the capacitor. 5. The two most common problems with power seats are a tripped or constantly tripping circuit breaker and the inability of th e seat to move in the desired direction due to binding or obstructions. 6. d. Neither technician is correct. If none of the locks work, check the circuit protection devices and the wiring. If all of the locks operate to lock or unlock, but not both, check the relays, if so equipped, or the wiring from the control switch to the side not working. 7. False. On some passkey systems, a new password must be learned by a replacement PCM or BCM; the key is not reprogrammed with a new password. 8. a. Most horn circuits provide battery current flowing from the horn lead, through an electromagnetic coil in the horn relay to ground. Other circuits use ground-side switching as stated by Technician B, but they also must use a relay, and so Technician B is incorrect. 9. a. The timer operates the defogger for a predetermined time period. 10. b. The window motor ground is through the right door switch and the master switch. 11. a. Park is accomplished because the park switch opens when the blades are in their lowest position and the wiper switch is in the off position. 12. c. Either binding mechanical linkage or excessive electrical resistance can cause slower-than-normal wiper operation. 1.
Electrical Accessories
13.
14. 15.
16. 17.
18.
19.
20.
93
c. Both technicians are correct. When power seats do not operate in any switch position, check for a tripped circuit breaker, check the power and ground circuits, and, finally, check for continuity in each switch position. Refer to the service manual for the expected continuity between the various terminals of the switch. c. Both technicians are correct. Antitheft systems may have features that sound an alarm, disable the ignition, or deny entry to the vehicle. a. A continuously tripping circuit breaker may be caused by binding or mechanical resistance. Check the seat tracks and under the seat for obstructions. High electrical resistance causes a decrease, not an increase in current flow, and would be unlikely to cause the circuit breaker to trip. b. Keys equipped with a transponder return a radio signal to the PCM. A resistance key has a small resistor, not a thermistor, bonded to it. True. On vehicles with electronic throttle control (drive-by-wire) the circuitry in the PCM operates the cruise control without the need for modules, cables, or stepper motors. b. Devices used to trigger an alarm may include mechanical switches, ultrasonic sensors, or current-sensitive sensors. The majority of law enforcement officials recommend an audible alarm, not a silent page as stated by Technician A. c. Both technicians are correct. Navigational systems rely on global positioning satellites, and a computer inside the vehicle compares the data it receives from the satellite with information stored in memory, or that it reads from a compact disc or DVD. d. All of the above.
TECH MANUAL
The following procedures are included in Chapter 22 of the
Tech Manual:
1. Testing and repairing a rear-window defogger grid. 2. Performing a speed or cruise control simulated road test. 3. Identifying the source of static on a radio.
ANSWERS TO TECH MANUAL REVIEW QUESTIONS 1.
2. 3. 4. 5. 6. 7.
The window lock switch is included in the four-door model window switch. When the switch is open, this switch limits opening and closing of all windows to the master control switch. It is designed to prevent children from operating door windows without the driver’s knowledge. Cruise control switch, vehicle speed transducer, servo unit, and two brake-activated switches The sensor for rain-sensing wipers is typically located in the center and at the top of the windshield behind the rear view mirror. False True The transducer senses vehicle speed and controls the amount of vacuum that is applied to a vacuum servo. True
94
Chapter 22
8. 9. 10.
11. 12. 13. 14. 15.
Binding in wiper mechanical linkage, faulty harness connections, and faulty motor assembly Vacuum, electronic, and adaptive A sensor prevents the window from closing if something is in the way such as fingers. There are two designs: obstacle sensing in which physical contact is made and infrared sensing in which the beams are broken by the object. Both systems will cause the window to move to the open position. True Traffic and travel information Cell phone Locking, disabling, and alarm 25 to 50 feet (7.62 to 15.24 meters)
23 RESTRAINT SYSTEMS: THEORY, DIAGNOSIS, AND SERVICE
CHAPTER OVERVIEW Safety is a primary consideration not only in the design of automobiles, but also in the purchase decision made by consumers. Many safety features are available either as standard equipment or as options. This chapter describes restraint systems and how to diagnose and service them.
CHAPTER OBJECTIVES Identify and describe devices that contribute to automotive safety. Explain the difference between active and passive restraint systems. Know how to service and repair passive belt systems. Describe the function and operation of air bags. Identify the major parts of a typical air bag system. Safely disarm and inspect an air bag assembly. Know how to diagnose and service an air bag system.
INSTRUCTIONAL OUTLINE WITH TEACHING HINTS I.
II.
III.
Restraint Systems A. Active Restraints B. Passive Restraints Seat Belts A. Seat Belt Retractors B. Warning Lights Seat Belt Service A. Webbing Inspection B. Buckle Inspection C. Retractor Inspection D. Drive Track Assembly and Anchor Inspection E. Rear Seat Restraint System F. Warning Light and Sound Systems G. Servicing Seat Belts
95
96
Chapter 23
IV.
V. VI.
Air Bags A. Electrical System Components 1. Sensors (a) Roller-Type Sensors (b) Mass-Type Sensor (c) Accelerometer 2. Diagnostic Monitor Assembly 3. Wiring Harness 4. Clockspring 5. SIR or Air Bag Readiness Light Hint: Show several air bag sensors and explain how they operate. If possible, show an air bag that has been deployed. Arrange for students to observe the deployment and disposal of an air bag. Emphasize the safety practices the students need to know when working around areas of the vehicle related to air bags. B. Air Bag Module C. Diagnosis 1. Retrieving Trouble Codes (a) Scan Tool DTC Retrieval (b) Flash Codes Servicing the Air Bag System A. Service Guidelines Other Protection Systems A. Head Rests B. Rollover Protection
ANSWERS TO TEXTBOOK REVIEW QUESTIONS 1.
2. 3. 4. 5. 6. 7. 8.
9. 10.
11.
An active restraint requires the vehicle’s occupant to make a manual effort such as buckling a seat belt in place; a passive system operates automatically, with no action required of the occupant to make it functional. False. Air bags are generally inflated using heated nitrogen gas. The air bag module includes an igniter assembly having one or more squibs containing zeronic potassium perchlorate (ZPP). True. The air bag diagnostic monitor provides backup power. c. Both technicians are correct. a. Seat belt webbing should be replaced if it is bowed or if it is discolored due to exposure to the sun. True. The powdery substance on a deployed air bag may contain sodium hydroxide. c. Both technicians are correct. Certain faults cause the system to disarm. To prevent accidental deployment, at least two sensor switches must close in order to deploy the air bag. b. During a severe collision, when maximum protection is needed, both squibs fire at the same time. b. Test webbing sensitive retractors by jerking on the belt. To test vehicle-sensitive retractors requires driving the vehicle and having an assistant test the retractor during a stop. b. The gas generated to inflate the air bag in this system is nitrogen, not zeronic potassium perchlorate as stated.
Restraint Systems: Theory, Diagnosis, and Service
12.
13.
14. 15. 16. 17. 18. 19. 20.
97
a. When repairing air bag systems it is best to also service other related components in assembly groupings. Never back probe an air bag system with a self- powered multimeter, or a test light, unless you want to observe firsthand a very expensive bag deployment. c. Wear safety glasses and gloves when handling deployed air bags because there may be caustic residue on the module, and two-stage bags may have only deployed the first stage and could still be armed. Disconnect the negative battery cable and wait at least 30 minutes before servicing the air bag system. a. Passive restraints such as seat belts must operate automatically, with no action required by the vehicle’s occupant. False. Wait at least 30 minutes before beginning any service on or around the air bag system. c. Both technicians are correct. c. Both technicians are correct. a. Roller-type sensors rely on the roller that is held against a stop by small springs, not a magnet. c. Seat belt retractors can help limit the forward movement of the occupant, but they cannot pull the occupant back during a crash. Crumple zones are areas of the vehicle’s body that bend or break away to protect passengers.
TECH MANUAL
The following procedures are included in Chapter 23 of the
Tech Manual:
1. Inspecting seat belts. 2. Working safely around air bags.
ADDITIONAL TEACHING HINTS Demonstrate the recommended method to disable the air bag systems and explain when this is necessary. Arrange for the students to witness the deploying of an air bag prior to its disposal. Dealership parts/service departments, body shops, and factory training facilities are possible sources for this activity.
ANSWERS TO TECH MANUAL REVIEW QUESTIONS 1. Systems that 2. a. webbing b. buckle
operate automatically without an action by the driver or passenger
retractor anchors 3. Disconnect the positive battery cable and wait one minute. 4. With the horn pad facing up and the aluminum or metallic housing facing down 5. No 6. No c. d.
