Class 12 Automotive Chapter 5 Auto Electrical System

Class 12 Automotive Chapter 5 Auto Electrical System Solutions English Medium As Per AHSEC New Syllabus to each chapter is provided in the list so that you can easily browse through different chapters Class 12 Automotive Chapter 5 Auto Electrical System Question Answer and select need one. Class 12 Automotive Chapter 5 Auto Electrical System Notes Download PDF. AHSEC Class 12 Elective Automotive Question Answer English Medium.

Class 12 Automotive Chapter 5 Auto Electrical System

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Also, you can read the NCERT book online in these sections Solutions by Expert Teachers as per Central Board of Secondary Education (CBSE) Book guidelines. AHSEC Class 12 Elective Automotive Textual Solutions are part of All Subject Solutions. Here we have given AHSEC Class 12 Automotive Textbook Solutions English Medium for All Chapters, You can practice these here.

Auto Electrical System

Chapter: 5

A. Fill in the blanks:

1. The symbol for an electrical wire represents the _____________. 

Ans: Electrical wire.

2. Resistor reduces the flow of _____________ in an electrical circuit. 

Ans: Current.

3. Neoprene rubber is often used as insulation for cables due to its resistance to ___________, oil, and heat. 

Ans: Heat.

4. High-tension (HT) cables are used to connect the _____________ to the spark plugs. 

Ans: Ignition coil.

5. The purpose of a wiring harness is to simplify connections and prevent damage from ____________ objects.

Ans: Metal.

B. Multiple Choice Questions:

1. What is the purpose of using automotive electrical symbols? 

(a) To confuse mechanics. 

(b) To simplify circuit diagrams.

(c) To increase voltage.

(d) To generate light.

Ans: (b) To simplify circuit diagrams.

2. Which type of switch disconnects the current when open? 

(a) SPST Toggle Switch.

(b) Pushbutton Switch (N.O). 

(c) SPDT Relay. 

(d) Jumper.

Ans: (a) SPST Toggle Switch.

3. What does a resistor do in an electrical circuit? 

(a) Increases voltage. 

(b) Reduces current flow. 

(c) Acts as a switch. 

(d) Generates light. 

Ans: (b) Reduces current flow. 

4. Which cable is used for the battery circuit? 

(a) Black. 

(b) Green. 

(c) Yellow. 

(d) Brown. 

Ans: (d) Brown.

5. What is the primary purpose of a wiring harness in automobiles? 

(a) To confuse mechanics. 

(b) To increase voltage. 

(c) To simplify connections. 

(d) To generate heat.

Ans: (c) To simplify connections.

6. Which cable is used for the headlamp circuits? 

(a) White. 

(b) Blue. 

(c) Red. 

(d) Black.

Ans: (b) Blue. 

C. Answer the following questions:

1. Draw a neat diagram of following items in symbolic form. 

(a) Fuse.

Ans: —[ ∎ ]—

(A simple rectangle/box in the middle of a line, representing a fuse element that breaks if current is too high.)

(b) Relay.

Ans:  

(A relay consists of a coil and a switch that it controls. The coil symbol and movable switch contact are shown separately.)

(A relay consists of a coil and a switch that it controls. The coil symbol and movable switch contact are shown separately.)

(c) Transistor.

Ans: There are three main types; here is NPN transistor (most common):

(C = Collector, B = Base, E = Emitter. Arrow points out for NPN, in for PNP.)

(d) LED.

Ans: 

(A diode symbol with two outward arrows showing light emission.)

(e) Ground.

Ans: ───

        ──

        ─

(A set of three decreasing horizontal lines stacked vertically, pointing downward.)

2. Write various specifications of Automobile cables.

Ans: Various kinds of cables are employed in the wiring system of present-day automobiles. While selecting the cable size, the voltage drop is kept in mind. Generally, the voltage drops permitted for a particular length of cable under its full current loading capacity is of the order of 10%.

The cables used in automobiles are of the stranded type instead of the single-conductor type. The stranded cables are more flexible than the single one but they are not easily soldered. The size of the cable is designated by the number of

strands and the diameter of each wire used. For instance, a cable having 37 strands of wire, each of 0.875 mm diameter, is designated as a 37/0.875 cable.

3. What do you understand by cable color codes? Classify the Automobile cables. 

Ans: In order to quickly identify and also to simplify the wiring system, the cables are coloured. In addition, colour lines or threads are also used around the cables, which provide a very wide choice of colour combinations. The seven colour code system is the general one and involves brown, yellow, red, white, green, blue and black colours.

(i) Brown Cables: Brown cables are used for the battery circuit. It is used from the cranking motor switch to the ammeter, to the radio receiver, to the electric clock, to the inspection sockets and to the battery auxiliary fuse.

(ii) Yellow Cables: These are used for the generator circuits. The cable is used from the generator terminal to the corresponding control-box terminal and to the ignition warning light.

(iii) White Cables: These cables are used for the ignition circuits and also for other circuits which do not require fuses and are operated through the ignition switch, such as the electric fuel pump, motor starter, solenoid switch etc.

(iv) Green Cables: These cables are used for all the auxiliary circuits which are fed through the ignition switch but are protected by the fuses. Examples of these circuits are the brake stop lamps, the fuel gauge, the windscreen wipers, the direction indicators, etc.

(v) Blue Cables: These cables are used for the headlamp circuits. These cables are used for the side and tail lamp circuits. It is also used for fog lamps, panel lights and other lamps which are only used when the side lamps are in operation.

(vi) Black Cables: These cables are used for the earth circuits.

4. What is Wiring Harness? How does it affect the electrical connections in Automobile?

Ans: The electrical system of present-day cars is quite complex. Connecting each electrical component individually is a tedious and costly affair. With the adoption of the wiring harness method, it has become quite simple to connect the various electrical components. It has also resulted in space saving and safeguarding of the individual cables from metal objects.

The harness consists of bunches of cables leading to the various components to be connected. Each bunch is bound together with a PVC tape, leaving sufficient lengths of individual cables protruding at each end for making the necessary electrical connections easily.

It may be noted that there is a typical drawback to this system. If one of the cables fails, it necessitates the harness to be cut for rectification. However, the present-day cables have got good mechanical strength as well as insulation properties.

A. Fill in the blanks:

1. One of the simplest types of test equipment is the _______________ wire. 

Ans: Jumper.

2. A test light is limited in that it does not display the ____________ at the point of the circuit being tested. 

Ans: Voltage.

3. Digital multimeters (DMMs) are preferred for testing computer circuits due to their high input resistance, which reduces the risk of ___________ to components. 

Ans: Damage.

4. An oscilloscope displays voltage traces on a screen, representing voltage variations over ____________. 

Ans: Time.

B. Multiple Choice Questions: 

1. What is the primary purpose of using jumper wires in electrical testing? 

(a) To measure resistance.

(b) To diagnose voltage drops.

(c) To provide a ground for testing.

(d) To bypass load components.

Ans: (d) To bypass load components.

2. Which tool is used to “look” for electrical power in a circuit? 

(a) Voltmeter.

(b) Ammeter.

(c) Logic probe.

(d) Ohmmeter.

Ans: (c) Logic probe.

3. Which type of multimeter is recommended for testing computer-controlled circuits due to its high input resistance? 

(a) Analog multimeter.

(b) Digital multimeter (DMM).

(c) Ohmmeter.

(d) Logic probe.

Ans: (b) Digital multimeter (DMM).

4. What is the purpose of a logic probe in electrical testing? 

(a) Measure voltage drops.

(b) Test diodes.

(c) Measure frequency.

(d) Test computer-controlled circuits.

Ans:( d) Test computer-controlled circuits.

5. In a circuit, the sum of voltage drops around the circuit is equal to: 

(a) Zero.

(b) The source voltage.

(c) Infinity.

(d) Half of the source voltage.

Ans: (b) The source voltage.

C. Answer the following questions:

1. Discuss the importance of electrical test equipment’s in the testing of automobile electrical circuits. 

Ans: Since electricity is an invisible force, the proper use of test tools will permit the Assistant to ‘See’ the flow of electrons. Knowing what is being looked at and being able to interpret various meter types will assist in electrical system diagnosis. To diagnose and repair electrical circuits correctly, a number of common tools and instruments are used.

2. Name various electrical test equipment’s used in automobile.

Ans: The most common tools are jumper wires, test lights, voltmeters, ammeters, ohmmeters etc.  

3. With the help of multi-meter what are the parameters can be tested? 

Ans: A multimeter is an electrical test meter capable of measuring-

(i) Voltage.

(ii) Resistance (in Ohms).

(iii) Current Flow (in ampere).

4. Explain how to test following parameters with the help of multi-meters? 

(a) Voltage. 

Ans: In a multimeter AC and DC voltage can be checked with the proper selection of the switch. You can measure voltage available in a circuit with or without current flowing. Voltage without current flow is open-circuit voltage and should equal battery, or source, voltage. When current flows through a circuit, the circuit device uses, or

drops, some voltage as they operate. Voltage on one side of a load will be different from the voltage on the other side when the circuit is closed and operating.

(b) Current. 

Ans: Before connecting multimeter prods into a circuit, set the range selector switch to the range above the maximum expected current draw… If the meter shows no current, the circuit is open at some point. If the meter shows low current, the circuit is complete but has high resistance. If the meter shows too high current, some of the normal resistance has been bypassed to ground or through a short circuit.

(c) Resistance. 

Ans: The circuit being tested, an open or excessive resistance can be detected. The meter sends a current through the component and determines the amount of resistance based on the voltage drop across the load. The meter reads from zero to infinity. A reading of zero means there is no resistance in the circuit. If the meter indicates an infinity reading, this means the resistance is higher than the meter can read on the selected scale. If an infinity reading is obtained on the highest scale this usually indicates the circuit has an open.

5. Explain regarding the Oscilloscope. What are the parameters can be checked with the help of Oscilloscope? 

Ans: The Oscilloscope is very useful in diagnosing many electrical problems quickly and accurately. Digital and analog voltmeters do not react fast enough to read systems that cycle quickly. The oscilloscope may be considered as a very fast reacting voltmeter that reads and displays voltages. The scope allows the Assistant to view voltage over time. These voltage readings appear as a voltage trace on the oscilloscope screen. An upward movement of the voltage trace on an oscilloscope screen indicates an increase in voltage, and a downward movement of this trace represents a decrease in voltage. As the voltage trace moves across an oscilloscope screen, it represents a specific length of time.

A. Fill in the blanks: 

1. Battery acid is very ____________. If it comes in contact with skin, wash with clean water. 

Ans: Corrosive. 

2. When connecting battery cables, always connect the ____________ cable last. 

Ans: Negative.

3. Avoid any ____________ or open flames near a battery, as the vapors produced can be explosive. 

Ans: Sparks.

4. To clean a battery, you can use a solution of baking soda and water or ____________. 

Ans: Ammonia.

5. Battery’s state of charge can be determined by testing the specific gravity of the ____________ using a hydrometer. 

Ans: Electrolyte.

6. The open circuit voltage test is used to determine the battery’s ____________, and it is performed when a hydrometer is not available.  

Ans: State of charge.

B. Multiple Choice Questions:

1. What is the purpose of battery inspection and cleaning in the automotive electrical system? 

(a) To increase battery capacity. 

(b) To reduce battery voltage. 

(c) To prevent dirt and corrosion buildup. 

(d) To enhance engine performance. 

Ans: (c) To prevent dirt and corrosion buildup. 

2. When making connections to a battery, which of the following should you observe? 

(a) Connect positive to negative. 

(b) Connect negative to positive. 

(c) Observe no specific polarity. 

(d) Connect positive to positive and negative to negative. 

Ans: (d) Connect positive to positive and negative to negative. 

3. What is the purpose of adding baking soda to water when cleaning a battery? 

(a) To make the water conductive. 

(b) To neutralize battery acid. 

(c) To increase the battery’s capacity.

(d) To remove rust from terminals. 

Ans: (b) To neutralize battery acid. 

4. Why should you avoid laying tools across a battery? 

(a) It might discharge the battery. 

(b) It could damage the tools. 

(c) It might cause a short circuit. 

(d) It could lead to battery freezing. 

Ans: (c) It might cause a short circuit. 

5. Which type of cable should you disconnect first when working on a battery? 

(a) Positive (hot) cable. 

(b) Negative (ground) cable. 

(c) Both cables simultaneously. 

(d) It doesn’t matter which one you disconnect first. 

Ans: (b) Negative (ground) cable. 

6. What should you wear to protect your eyes while servicing a battery? 

(a) Gloves. 

(b) Earplugs. 

(c) Safety glasses or a face shield. 

(d) A hard hat.

Ans: (c) Safety glasses or a face shield.

C. Answer the following questions:

1.Explain the importance of battery and its maintenance in automobile.

Ans: The Battery is the Heart of the Automotive Electrical System. The battery must be in good usable condition for the rest of the electrical system to function correctly. In this chapter we describe the battery service and testing methods necessary to assure proper battery operation.

2. Write various precautions to be observed while handling the lead acid battery. 

Ans: “Before attempting to do any type of work on or around the battery, the Assistant must be aware of certain precautions. 

To avoid personal injury or property damage, take the following precautions:

(i) Battery acid is very corrosive. Do not allow it to come in contact with skin, eyes, or clothing. If battery acid gets into your eyes, rinse them thoroughly with clean water and receive immediate medical attention. If battery acid comes in contact with skin, wash with clean water. Baking soda added to the water will help to neutralize the acid. If the acid is swallowed, drink large quantities of water or milk followed by milk of magnesia and a beaten egg or vegetable oil.

(ii) When making connections to a battery, be careful to observe polarity (positive to positive and negative to negative).

(iii) When disconnecting battery cables, always disconnect the negative (ground) cable first.

(iv) When connecting battery cables, always connect the negative cable last.

(v) Avoid any arcing or open flames near the battery. The vapors produced by the battery cycling are very explosive. Do not smoke around a battery.

(vi) Follow manufacturer’s instructions while charging the battery. Charge the battery in a well-ventilated area. Do not connect or disconnect the charger leads while the charger is turned on.

(vii) Do not add additional electrolyte to the battery if it is low. Add only distilled water.

(viii) Do not wear any jewelry or watches while servicing the battery. These items are excellent conductors of electricity. They can cause severe burns if current flows through them by accidental contact with the battery positive terminal and ground.

(ix) Never lay tools across the battery. They may come into contact with terminals, sorting out the battery and causing it to explode.

(x) Wear safety glasses or face shield when servicing the battery.

(xi) If the battery’s electrolyte is frozen, allow it to defrost before doing any service or testing of the battery. While it is defrosting, look for leaks in the case. Leakage means the battery is cracked and should be replaced.

3. Write the procedure of inspection and cleaning of a battery.

Ans: Battery Inspection: Complete battery inspections consist of the following eight steps but take only a couple of minutes to do.

(i) If the battery has removable cell caps, check the electrolyte level. It should be above the tops of the plates or at the split-ring indicator level in each cell. Add distilled water to raise the electrolyte level, if necessary. Do not overfill the battery.

(ii) Check for missing or damaged cell caps, replace as required.

(iii) Check battery terminals, cable connectors, and metal hold-down parts for acid corrosion. Clean as required.

(iv) Check the cables for broken or corroded wire strands, worn insulation, and defective connectors. Replace defective parts.

(v) Check the battery case and cover for dirt, grease, or electrolyte condensation that could cause voltage to leak to ground. Clean battery as necessary.

(vi) Inspect the battery for cracks, loose terminals, and other damage. Replace a damaged battery.

(vii) Check the battery carrier (tray) hold-down parts, and heat shields for looseness or improper installation. Tighten or replace loose or damaged parts.

(viii) If the battery has a built-in hydrometer (state-of-charge indicator), check its colour indication for general battery condition.”

Battery Cleaning: Periodic battery cleaning eliminates these two problems of voltage leakage (discharge) and circuit resistance. Through battery cleaning consists of the following steps:

(i) Wash the battery top, case, and hold-down parts with a mixture or baking soda and water or with house-hold ammonia. These solutions neutralize acid and dissolve corrosion.

(ii) Remove heavy corrosion with a stiff-bristled brush. Do not splash corrosion or the cleaning solution onto painted surfaces.

(iii) After neutralizing acid and corrosion with baking soda or ammonia, wash the battery with detergent and water to remove dirt. Rinse with clear water from a hose or bucket.

(iv) Dry the battery, the cables, the hold-down parts, and adjoining vehicle parts with a clean cloth or low pressure compressed air.

(v) Cleaning the outside of battery terminals and cables often does not remove corrosion that forms between the cable connectors and terminals. Starting with the ground cable, remove the cable connectors from the terminals…

(vi) Wash the battery terminals and cable connectors with a baking soda solution or ammonia to remove all corrosion.

(vii) Scrape battery posts and the insides of cable connectors with wire brushes…

(viii) After cleaning cable connectors and battery terminals, dry them with a clean cloth or low-pressure compressed air.

(ix) Remove and clean corroded hold-down part with the same methods used for battery cables and terminals.

(x) Starting with insulated (positive or “hot” cable, reconnect the battery cables and reinstall hold-down parts securely.

4. Name various tests carried out on a lead acid battery and explain each one of those tests. 

Ans: When the battery and cables have been completely inspected and any problems have been corrected, the battery is ready to be tested further. Before carrying out any tests on the battery ensure that it is fully charged.

(i) Battery terminal test: The battery terminal test checks for poor electrical connections between the battery cables and terminal. If the voltmeter shows over 0.3 volts, there is a high resistance at the cable connection.

(ii) Leakage Test: If no apparent damage is visible the battery should be subjected to a leakage test using the battery leakage tester. Any battery which fails this test should be rejected.

(iii) Insulation Test: Before a battery is used from the charging room it should be tested for insulation resistance between the battery terminals and the metal case using a 250 V insulation tester (megger). The minimum permissible reading is 0.5 meg. Ohms.

(iv) State of Charge Test (Specific Gravity / Hydrometer Test): Measuring the state of charge is a check of the battery’s electrolyte and plates. It can be determined by testing the specific gravity of the electrolyte using a hydrometer… The float rises and the specific gravity is read where the float scale intersects the top of the solution.

5. Write different faults occur in lead acid battery, their causes and remedies. 

Ans: The different faults occur in lead acid battery, their causes and remedies are:

(i) Battery does not take charge:

Causes: Sulphation, broken connections.

Remedies: Replace electrolyte, repair or replace battery.

(ii) Battery discharges quickly:

Causes: Short circuit, dirt or moisture on top of battery. 

Remedies: Clean and dry battery, replace defective cells.

(iii) Battery gets overheated:

Causes: Overcharging, internal short. 

Remedies: Correct charging rate, replace defective battery.

(iv) Low specific gravity of electrolyte:

Causes: Loss of electrolyte due to leakage or evaporation. 

Remedies: Add distilled water, repair leaks.

(v) Corroded terminals:

Causes: Acid vapors, poor maintenance. 

Remedies: Clean and apply petroleum jelly/protective coating.

A. Fill in the blanks:

1. Circuit testing is a ____________ approach to locating the cause of a problem in a vehicle’s lighting system. 

Ans: Systematic.

2. To effectively diagnose a circuit problem, it’s important to understand how the circuit should _______________. 

Ans: Work.

3. Checking for _______________ involves cleaning and tightening the ground connection before testing. 

Ans: Ground.

4. A short to ground can be located by using a self-powered test lamp or ____________, with power disconnected from the circuit. 

Ans: Ohmmeter.

5. When using a voltmeter to check for voltage, the reading should be within ____________ of battery voltage. 

Ans: One volt.

6. In an unfused circuit, if there is a short to ground, the conductor may ____________ and possibly burn. 

Ans: Over heat.

B. Multiple Choice Questions: 

1. What is the purpose of checking the lighting system in a vehicle?

(a) To save fuel. 

(b) To reduce emissions. 

(c) To ensure vehicle safety and compliance with laws. 

(d) To increase engine performance. 

Ans: (c) To ensure vehicle safety and compliance with laws.

2. Which of the following is NOT a component of a lighting circuit in a vehicle? 

(a) Circuit protector.

(b) Engine block. 

(c) Switch. 

(d) Connector.

Ans: (b) Engine block.

3. What is the potential danger if a lighting circuit in a vehicle is not operating properly? 

(a) Increased fuel efficiency.

(b) Enhanced driving experience.

(c) Risk to driver and other people.

(d) Improved audio system performance. 

Ans: (c) Risk to driver and other people.

4. Which tool is used to check for voltage in a lighting circuit? 

(a) Hammer.

(b) Screwdriver.

(c) Test lamp or voltmeter.

(d) Pliers.

Ans: (c) Test lamp or voltmeter.

5. Why should a test lamp not be used in circuits containing solid-state components? 

(a) It can improve circuit performance.

(b) It may damage the circuit or components.

(c) It can increase circuit resistance.

(d) It may cause overheating of wires.

Ans: (b) It may damage the circuit or components.

6. How can you locate a short to ground in a wiring circuit? 

(a) By disconnecting the load and fuse, then wiggling the wiring.

(b) By increasing the circuit voltage.

(c) By using a test lamp only.

(d) By disconnecting the battery.

Ans: (a) By disconnecting the load and fuse, then wiggling the wiring.

C. Answer the following questions:

1. Discuss the importance of checking of electrical connections of lighting system in a vehicle. 

Ans: The lighting system of a vehicle is one of the most important safety systems. It enables the driver to see the road clearly at night and under adverse weather conditions and ensures that the vehicle is visible to other road users. Checking of the lighting system is important to prevent accidents, to comply with traffic regulations, and to ensure safe driving.

2. Write the general procedure of testing the automobile lighting circuit for following parameters. 

(a) Voltage.

Ans: Connect the voltmeter across the load and measure the voltage. The reading should be within one volt of the battery voltage.

(b) Ground.

Ans: Check the ground connection by cleaning and tightening it before testing. Poor ground connections can cause malfunction of the lighting circuit.

(c) Shorting. 

Ans: Remove the load and fuse. Connect a self-powered test lamp or ohmmeter across the circuit. Then wiggle the wiring. The lamp will glow or the ohmmeter will show continuity if there is a short.

(d) Continuity.

Ans: Disconnect the power. Connect a self-powered test lamp or ohmmeter across the circuit. A glow of the lamp or continuity reading indicates proper continuity in the wiring.

3. Draw a circuit diagram of Lighting system of any Indian car.

Ans: The circuit diagram of the lighting system of an Indian car is:

4. Write different fault of lighting system of a car, their causes and remedies.

Ans: The various faults, their causes, and remedies in a car lighting system are:

A. Fill in the blanks:

1. The primary purpose of fuses is to protect electrical circuits from the detrimental effects of _____________. 

Ans: Excessive currents.

2. Blade-type fuses are characterized by flat plastic units with _____________ male blade-type connectors. 

Ans: Two.

3. Cartridge-type fuses, commonly used in older European vehicles, have pointed ends and a metal strip that extends from ______________ to ______________. 

Ans: One end to the other end.

4. Fuse identification and specifications can usually be found on the _____________ or the cover of the fuse box. 

Ans: Fuse box.

5. When replacing a fuse, it’s important to ensure that the new fuse has the correct ______________ and _______________. 

Ans: Size and type.

B. Multiple Choice Questions: 

1. Fuses are used for protecting electrical circuits and equipment against the effects of: 

(a) Voltage spikes.

(b) Excessive currents.

(c) Magnetic fields.

(d) Static electricity.

Ans: (b) Excessive currents.

2. In the case of a greater number of fuses, each fuse might protect: 

(a) A single electrical item.

(b) A specific type of circuit.

(c) A group of electrical items.

(d) All lighting circuits.

Ans: (c) A group of electrical items.

3. Which fuse is commonly used to protect circuits controlled by the ignition switch? 

(a) 15 A.

(b) 25 A.

(c) 35 A.

(d) 50 A.

Ans: (c) 35 A.

4. The three basic types of fuses include glass or ceramic fuses, blade-type fuses, and: 

(a) Bullet or cartridge fuses.

(b) Wire fuses.

(c) Fiber fuses.

(d) Magnetic fuses.

Ans: (a) Bullet or cartridge fuses.

C. Answer the following questions:

1. Discuss the importance of applications and replacement of fuses in a vehicle. 

Ans: Fuse is used in electrical circuits to protect the circuit against short circuiting or excessive currents. The fuse is a sacrificial device which breaks or melts when subjected to more than rated current. This protects the circuit components like wires, switches, relays, etc. from burning. It is important that the correct rating of fuse is used and if it is blown it must be replaced immediately with one of the same value.

2. Name different types of fuses and explain. 

Ans: The different types of fuses used in automobile electrical system are:

(i) Glass tube or ceramic fuses: They are cylindrical in shape and made of glass or ceramic material. The fuse element is a thin wire inside the tube.

(ii) Blade type fuses: These are flat plastic fuses with two blade connectors, commonly used in modern automobiles.

(iii) Cartridge or bullet type fuses: These fuses are cylindrical with pointed ends, used in older European vehicles. They contain a metal strip running from one end to the other.

3. Write the values of fuses used in different electrical system of automobile. 

Ans: The values of fuses used in different automobile electrical systems are as follows:

(i) Headlight circuit – 35 A.

(ii) Horn – 25 A.

(iii) Wiper – 15 A.

(iv) Ignition switch – 35 A.

(v) Tail light – 10 A.

(vi) Accessories – 10 A.

4. Explain colour coding of different fuses. 

Ans: The blade type fuses used in modern cars are colour coded for easy identification of their ratings. 

The colours indicate the following ratings:

(i) 2 A – Grey.

(ii) 5 A – Tan.

(iii) 7.5 A – Brown.

(iv) 10 A – Red.

(v) 15 A – Blue.

(vi) 20 A – Yellow.

(vii) 25 A – White.

(viii) 30 A – Green.

(ix) 40 A – Orange.

A. Fill in the blanks:

1. Routine maintenance of the alternator involves checking the __________ and ensuring the tightness of connecting bolts. 

Ans: Alternator Clean.

2. During the alternator testing on the vehicle, if the ignition warning lamp remains illuminated while the engine is running, it could be due to a __________. 

Ans: Drive belt slack.

3. Diodes can be tested individually using a 12-V battery and a warning lamp with test prods of __________ V and __________ W respectively. 

Ans: 12 V and 2.2 W.

4. If the ignition warning lamp fails to illuminate when the ignition is switched on, a possible cause could be a __________ or __________ connection. 

Ans: Defective bulb or fuse blown connection.

B. Multiple Choice Questions: 

1. What is the purpose of using alternators in modern vehicles instead of dynamos? 

(a) To increase generator speed.

(b) To decrease generator size. 

(c) To overcome brush and commutation limitations.

(d) To reduce electrical load.

Ans: (c) To overcome brush and commutation limitations.

2. What precaution should be taken before checking the charging system? 

(a) Disconnect the battery. 

(b) Flash the alternator output leads. 

(c) Use a slave battery to start the engine. 

(d) Ensure all connections are secure and clean. 

Ans: (d) Ensure all connections are secure and clean.

3. What should be the belt deflection when checking the driving belt’s condition? 

(a) 5 – 10mm. 

(b) 10 – 15mm.

(c) 15 – 20mm. 

(d) 20 – 25mm. 

Ans: (b) 10 – 15mm.

4. In the alternator checking procedure, if the warning lamp does not go off when the engine starts, what could be the issue? 

(a) Loose belt.

(b) Faulty ignition switch.

(c) Defective alternator.

(d) Disconnected battery.

Ans: (a) Loose belt.

5. What is the purpose of inserting an ammeter and a voltmeter during alternator testing? 

(a) To measure engine speed.

(b) To measure battery voltage.

(c) To measure field current and alternator voltage.

(d) To measure fuel consumption.

Ans: (c) To measure field current and alternator voltage.

6. If the voltage during engine speed of 50 km/h falls below 13.5V or above 14.4V, what might be the issue? 

(a) Faulty regulator. 

(b) Loose battery terminal. 

(c) Worn bearings. 

(d) Shorted phase in the stator.

Ans: (a) Faulty regulator.

C. Answer the following questions:

1. Name the importance of circuit diagram of charging system of automobile and checking of charging system in a vehicle. 

Ans: The circuit diagram of the charging system of automobiles is important to understand the connections and working of different components. Checking the charging system is essential to ensure that the battery is properly charged and electrical accessories work efficiently.

2. Draw the charging circuit of a modern car. 

Ans:

3. Explain the procedure of testing the charging circuit step by step. 

Ans: The procedure of testing the charging circuit is as follows:

(i) Insert an ammeter in series with the alternator output lead and connect the voltmeter across the battery.

(ii) Start the engine and run it at idling speed.

(iii) Note down the reading of ammeter and voltmeter.

(iv) Slowly increase the engine speed to about 50 km/h and observe the readings.

(v) The voltage should be between 13.5 V and 14.4 V.

(vi) If the voltage is less than 13.5 V, the regulator is faulty.

(vii) If the voltage is above 14.4 V, again the regulator is faulty.

4. Explain the procedure of testing the following: 

(a) Alternator Stator. 

Ans: Check the stator windings for continuity with the help of a continuity tester. If there is no continuity, the winding is open. Also check for short to ground.

(b) Alternator Rotor. 

Ans: Check the rotor winding with the help of a continuity tester. If there is no continuity, the winding is open. Also check slip rings for continuity and insulation.

(c) Rectifier.

Ans: Check each diode individually using a 12 V battery and a test lamp of 12 V, 21 W. Connect the positive lead to the anode and negative to the cathode. The lamp should glow in one direction only. If it glows in both directions or does not glow at all, the diode is faulty.

5. Write different faults may occur in the charging circuit, their causes and remedies.

Ans: The different faults that may occur in the charging circuit, their causes and remedies are:

A. Fill in the blanks:

1. The starter motor converts electrical energy into ____________ motion to crank the engine. 

Ans: Mechanical.

2. To check the continuity between the terminal lead and the brush, a continuity test is performed using a ____________.  

Ans: Multimeter.

3. If the commutator is rough or worn, it can be smoothed using ____________ paper. 

Ans: Abrasive.

4. In the event of no cranking and dim lights, a possible cause could be an ____________ circuit in the switch. 

Ans: Open.

5. A weak shift lever return ____________ can lead to the pinion disengaging slowly after the engine has started.

Ans: Spring.

B. Multiple Choice Questions: 

1. The electric starter system of an automobile includes which of the following components? 

(a) Alternator, carburetor, spark plugs.

(b) Battery, ignition lock, starter motor.

(c) Radiator, transmission, throttle body.

(d) Exhaust pipe, fuel pump, brake pads.

Ans: (b) Battery, ignition lock, starter motor.

2. What is the purpose of the Bendix pinion in the starter system? 

(a) To generate electricity.

(b) To engage the gears in the transmission.

(c) To rotate the crankshaft.

(d) To engage the starter motor with the engine’s flywheel.

Ans: (d) To engage the starter motor with the engine’s flywheel.

3. The armature in the starter motor is primarily responsible for: 

(a) Controlling the ignition timing.

(b) Holding the brushes in place.

(c) Converting electrical energy into mechanical motion.

(d) Regulating fuel flow to the engine.

Ans: (c) Converting electrical energy into mechanical motion.

4. Excessive resistance in the cranking motor circuit can result in: 

(a) Bright lights.

(b) Faster engine cranking.

(c) Slow engine cranking.

(d) Overheating of the starter motor.

Ans: (c) Slow engine cranking.

5. In a starter system, the solenoid plunger chattering is often caused by: 

(a) Low battery voltage.

(b) A defective ignition system.

(c) A short circuit in the control circuit.

(d) Overheating of the starter motor.

Ans: (a) Low battery voltage.

6. What is the purpose of the over-running clutch in the starter system? 

(a) To engage the Bendix pinion.

(b) To regulate fuel flow to the engine.

(c) To prevent the starter motor from overheating.

(d) To allow the engine to start even after the starter motor disengages.

Ans: (d) To allow the engine to start even after the starter motor disengages.

C. Answer the following questions:

1. Share importance of circuit diagram of starting system of automobile and checking of starter circuit in a vehicle. 

Ans: The circuit diagram of the starting system is crucial for understanding the electrical components involved in starting the engine. It helps in troubleshooting by visually representing the connections between the starter motor, battery, ignition switch, solenoid, and other essential components. The importance lies in:

(i) It makes it easy to find problems in the starting system.

(ii) It helps us understand how the electricity flows and makes sure all parts are connected properly.

(iii) It helps in fixing and maintaining the starting system quickly, so there’s less time spent on repairs.

2. Draw the circuit diagram of starting system of an Indian car. 

Ans: 

3. Explain the procedure of checking the starting circuit. 

Ans: The procedure of checking the starting circuit are:

(i) Disconnect the negative terminal of the battery.

(ii) Disconnect the starter motor connections.

(iii) Loosen and remove the starter motor assembly from the engine.

(iv) Disconnect the electromagnetic switch wiring.

(v) Inspect the magnetic switch assembly, commutator, and brushes for damage or wear.

(vi) Perform continuity tests across terminals using a multimeter to ensure all components are functioning correctly.

4. Write different faults may occur in the starting circuit, their causes and remedies.

Ans: The faults that  may occur in the starting circuit, their causes and remedies are:

A. Fill in the blanks:

1. In a distributor less ignition system, the Engine Control Unit (ECU) controls the transistors that break the __________ side of the circuit to generate the spark. 

Ans: Ground.

2. A transistorized ignition system uses a ____________ to control the on-off cycle of the ignition coil’s primary winding. 

Ans: Primary transistor.

3. One advantage of a computerized ignition system is its ability to precisely control the ignition ___________, leading to improved efficiency and emissions. 

Ans: Timing.

4. In a coil ignition system with CB point, the component responsible for opening and closing the circuit is the _____________. 

Ans: Contact breaker point.

5. The secondary winding of an ignition coil induces voltage into the ____________ circuit. 

Ans: Secondary.

6. One of the benefits of a transistorized ignition system is that it has no moving parts, which contributes to longer component ______________ and reduced maintenance. 

Ans: Life.

B. Multiple Choice Questions: 

1. In a coil ignition system with CB point, which component is responsible for opening and closing the circuit to generate the spark?

(a) Spark Plug.

(b) Rotor.

(c) Contact Breaker Point.

(d) Ignition Coil.

Ans: (c) Contact Breaker Point.

2. Which electronic component in a transistorized ignition system is responsible for controlling the ignition coil’s primary winding?

(a) Spark Plug.

(b) Camshaft.

(c) Distributor Cap.

(d) Primary Transistor.

Ans: (d) Primary Transistor.

3. What advantage does a computerized ignition system offer over traditional systems?

(a) Longer spark plug lifespan.

(b) Elimination of the battery.

(c) Improved control of ignition timing.

(d) Higher fuel consumption.

Ans: (c) Improved control of ignition timing.

4. In a distributor-less ignition system, what component controls the transistors to generate the spark?

(a) Camshaft.

(b) Distributor Cap.

(c) Engine Control Unit (ECU).

(d) Contact Breaker Point.

Ans: (c) Engine Control Unit (ECU).

5. What does a transistor in an ignition system function as?

(a) Relay.

(b) Switch.

(c) Battery.

(d) Spark Plug.

Ans: (b) Switch.

6. What does the secondary winding of an ignition coil induce voltage into?

(a) Battery.

(b) Camshaft.

(c) Primary Transistor.

(d) Secondary Circuit.

Ans: (d) Secondary Circuit.

A. Fill in the blanks:

1. During the troubleshooting of a horn assembly, if the fuse is blown, it should be __________ and the horn should be tested again. 

Ans: Replaced.

2. Electric fuel pumps can be of two types: the flexible diaphragm type and the motor-driven __________ type. 

Ans: Centrifugal.

3. To adjust the parking position of windshield wipers, the limit switch cover should be turned in the direction __________ to the motor crank rotation. 

Ans: Opposite.

4. If the oil pressure indicator lamp continues to glow even when oil pressure is adequate, the most likely cause is a __________ pressure sensor. 

Ans: Defective.

5. The purpose of cleaning the top of the fuel tank before removing the fuel pump is to ensure a clean __________ for the pump. 

Ans: Environment.

6. In an electronic return-less fuel system, the Fuel Pump Control Module (FPCM) controls the voltage supplied to the fuel pump to achieve the desired fuel __________ requested by the Engine Control Module (ECM).

Ans: Pressure.

B. Multiple Choice Questions: 

1. What is the purpose of testing switches and relays in a vehicle’s electrical system? 

(a) To adjust the sound quality of the horn.

(b) To determine the horn frequency.

(c) To check for voltage at the power feed terminal.

(d) To diagnose their serviceability.

Ans: (d) To diagnose their serviceability.

2. What should you do if a horn in a single-horn system does not sound when the horn button is pressed? 

(a) Replace the horn relay.

(b) Clean and tighten the horn switch ground connection.

(c) Check the circuit fuse.

(d) Replace the horn switch.

Ans: (c) Check the circuit fuse.

3. What is the advantage of an electric fuel pump over a mechanical pump in a vehicle’s fuel system? 

(a) It depends on the engine drive.

(b) It requires less maintenance.

(c) It is affected by under-bonnet temperatures.

(d) It can be located away from the engine.

Ans: (d) It can be located away from the engine.

4. What is a key factor that can cause fuel pump failure? 

(a) Low fuel level in the tank.

(b) Excessive fuel pressure.

(c) Use of high-octane fuel.

(d) Frequent use of additives.

Ans: (a) Low fuel level in the tank.

C. Answer the following questions: 

1. Discuss the importance of maintenance and servicing of major electrical accessories in a vehicle. 

Ans: Regular maintenance and servicing of electrical accessories in vehicles ensure their proper functioning, thereby increasing the vehicle’s reliability and lifespan. Electrical components such as the horn, fuel pump, fuel gauges, and others, are critical for the safe and efficient operation of the vehicle. Proper servicing prevents electrical failures, which could lead to dangerous situations or costly repairs. Moreover, regular maintenance reduces the likelihood of electrical system issues during critical moments, such as a vehicle breakdown or failure during operation.

2. Draw the circuit diagram of following:

(a) Dual Horn assembly.

Ans: 

(b) Electrical fuel pump.

Ans: 

(c) Electrical fuel gauges (balancing coil type and thermostatic type).

Ans: 

(d) Oil pressure gauge (balancing coil type).

Ans:

(e) Temperature gauge.

Ans: 

(f) Electric Speedo meter.

Ans: 

(g) Two speed windscreen wipers. 

Ans: 

3. Explain different fault, causes and remedies of following automobile accessories. 

(a) Dual Horn assembly.

Ans: 

(b) Electrical fuel pump.

Ans:

(c) Electrical fuel gauges (balancing coil type and thermostatic type).

Ans: 

(d) Oil pressure gauge (balancing coil type).

Ans: 

(e) Temperature gauge. 

Ans:

(f) Electric Speedo meter.

Ans: 

(g) Two speed windscreen wiper.

Ans: 

A. Fill in the blanks: 

1. The climate control system is designed to provide comfort for the ___________ and ________________. 

Ans: Driver, Passengers.

2. The HVAC system controls ___________ and the removal of ____________. 

Ans: Heat, Humidity.

3. The heater element is kept hot by means of _____________ of the radiator. 

Ans: Hot Water.

4. The __________ operates similarly to the heater, using heat from the same heater element. It directs hot air against the windshield to prevent condensation or freezing. 

Ans: Defroster.

5. The purpose of the __________ is to check whether the A/C system has the proper charge of refrigerant. It involves operating the A/C at maximum cooling capacity and observing the sight glass on the receiver/dryer.  

Ans: Sight Glass.

B. Multiple Choice Questions: 

1. The purpose of the climate control system in a vehicle is to: 

(a) Improve fuel efficiency. 

(b) Enhance vehicle speed. 

(c) Provide comfort for occupants. 

(d) Increase engine performance. 

Ans: (c) Provide comfort for occupants. 

2. Which of the following is NOT a subsystem of the HVAC system? 

(a) Cooling system. 

(b) Heating and defrosting system. 

(c) Air distribution and ventilation system. 

(d) Air conditioning system. 

Ans: (a) Cooling system.

3. The component that directs hot air against the windshield to prevent condensation or freezing is called the: 

(a) Vent door.

(b) Evaporator. 

(c) Defroster. 

(d) Compressor. 

Ans: (c) Defroster. 

4. What is the purpose of the blower motor in a vehicle’s HVAC system? 

(a) To control fuel injection. 

(b) To drive the vehicle. 

(c) To provide fresh air for ventilation. 

(d) To charge the battery. 

Ans: (c) To provide fresh air for ventilation.

5. In an air conditioning system, the compressor is driven by a belt and pulley from the: 

(a) Radiator fan. 

(b) Engine crankshaft pulley.

(c) Transmission. 

(d) Alternator.

Ans: (b) Engine crankshaft pulley.

6. What does the sight glass on the receiver/dryer of an A/C system indicate? 

(a) Oil level. 

(b) Engine temperature. 

(c) Refrigerant charge state. 

(d) Battery voltage. 

Ans: (c) Refrigerant charge state.

C. Answer the following questions: 

1. Discuss the importance of climate control system heating ventilation and air conditioning in a vehicle. 

Ans: The climate control system is designed to provide comfort for the driver and passengers. The climate control system maintains in-car air temperature and humidity within a range that is comfortable for the people inside and provides fresh clean air for ventilation. A comfortable temperature inside the vehicle helps keep the driver alert and attentive.

2. What do you mean by climate control in an automobile?

Ans: The air conditioning (A/C) system and the heating system are known together as heating, ventilation and air conditioning (HVAC) system. The HVAC system controls heat and the removal of humidity. The HVAC system uses an air distribution system of ducts, vents and doors to direct outside air or climate-controlled air into the vehicle passenger compartment. An electrical system provides the operator control of the HVAC system.

3. Write the functions of Heater and Defroster in automobile.

Ans: The heater system of a car uses a motor to drive the fan. The fan forces fresh air through the heater element into the interior of the car. The heater element is kept hot by means of hot water of the radiator. The motor gets its supply through the ignition switch.

The defroster operates like the heater. It also derives heat from the same heater element. The defroster directs the hot air against the windshield to avoid condensation or freezing of the moisture.

4. Draw the operational circuit of an automobile air conditioning system and label  

Ans: 

5. Different components. 

Ans: (i) Compressor: The pump that circulates refrigerant (driven from the engine crankshaft pulley).

(ii) Condenser: Heat exchanger where high-pressure refrigerant gives off heat (part of A/C refrigerant loop).

(iii) Receiver/dryer (with sight glass): Stores/filter moisture and lets you observe refrigerant condition/charge.

(iv) Expansion device/valve:  Reduces refrigerant pressure before the evaporator (part of refrigerant flow).

(v) Evaporator: Indoor heat exchanger where refrigerant absorbs heat from cabin air.

(vi) Heater core: Uses hot engine coolant (hot water) to produce cabin heat; part of HVAC heating/defrost system.

(vii) Blower motor/fan: Forces air through evaporator or heater core into cabin (ventilation).

(viii) Controls & sensors: Electrical control panel, switches, thermistor/thermostat, and ECM/controls that operate doors, blower and compressor clutch.

6. Explain different fault of automobile air conditioning system, their causes and remedies. 

Ans: Fault: V-belt too loose (or torn/slipping)

Cause: Belt slack → slippage, wear and tear.

Remedy: Tighten the belt; replace torn belt with a new one.

Fault: Noise around the compressor

Cause: Loose compressor mounting or bracket bolts.

Remedy: Check compressor mounting and bracket bolts; tighten as necessary.

Fault: Insufficient or excessive refrigerant charge

Cause: Under- or over-charging, leaks, or incorrect servicing.

Remedy: Evacuate system and recharge to correct specification; locate and repair leaks before charging.

Fault: Air or excessive compressor oil present in system

Cause: Contamination/incorrect oil quantity or improper service.

Remedy: Evacuate system, remove air/contaminants, correct oil amount and recharge.

Fault: Receiver/dryer clogged

Cause: Moisture, debris or breakdown of desiccant.

Remedy: Check and replace receiver/dryer.

Fault: Evaporator clogged or frosted (poor cooling or restricted airflow)

Cause: Dirt/debris, ice formation from improper refrigerant charge or blockage.

Remedy: Inspect and clean/repair evaporator; correct charge and system faults causing frosting.

Fault: Air leaking from cooling unit or air duct/Air inlet blocked

Cause: Damaged ducts, loose connections, or blocked inlet.

Remedy: Repair duct leaks, clear blockages, secure fittings.

Fault: Blower motor faulty (no airflow or intermittent airflow)

Cause: Motor failure, electrical fault, or resistor/control failure.

Remedy: Test blower motor/resistor/control; replace blower motor if defective.

Fault: Magnetic clutch/compressor/expansion valve/thermistor faults (system not cooling or not engaging)

Cause: Component failure, electrical fault, or improper charge.

Remedy/checks: Check magnetic clutch, compressor operation, expansion valve function and thermistor/sensor signals; repair or replace faulty component(s) and confirm correct refrigerant charge.

Parimol

Hi! my Name is Parimal Roy. I have completed my Bachelor’s degree in Philosophy (B.A.) from Silapathar General College. Currently, I am working as an HR Manager at Dev Library. It is a website that provides study materials for students from Class 3 to 12, including SCERT and NCERT notes. It also offers resources for BA, B.Com, B.Sc, and Computer Science, along with postgraduate notes. Besides study materials, the website has novels, eBooks, health and finance articles, biographies, quotes, and more.