TRADE OF HEAVY VEHICLE MECHANIC
Contents
1. 58 The two lights are located close to the widest points of the vehicle so that the vehicle width can be seen by other road users The bulbs ate connected in parallel to each other so that the failure of one filament will not cause total circuit failure A number plate illumination lamp is usually connected in parallel to the tail lights and operates whenever the tail lights are on This schematic diagram shows a conventional parking side light circuit The circuit is protected by fuses F4 F22 F23 and is switched through S3 note the 58 on the switch contacts EP3 EP3 PARKING LIGHT CIRCUIT EP2 EP14 Lhd EP12 EP12 30 31 Module 7 Unit 1 Basic Vehicle Wiring Headlights Modern headlights are electrically operated positioned in pairs one or two on each side of the front of a moving vehicle According to the DIN 72552 they are number 56a and 56b A headlamp system is required to produce a low and a high beam which may be achieved either by an individual lamp for each function or by a single multifunction lamp High beams called main beams ot full beams or driving beams in some countries cast most of their light straight ahead maximizing seeing distance but producing too much glare for S A75 A130 A162 36 36 E Li gt I o uM Mo mo A SM S MSSM HEAD LAMP CIRCUIT 30 x 31 Heavy Vehicle Mechanic Phase 2 19 Revision 2 0 December 20132. EP3 EP3 EP3 EP3 Module 7 Unit 1 Basic Vehicle Wiring safe use when other vehicles are present on the road The schematic diagram on page 19 shows a conventional headlamp circuit Terminal 56a and 56b on light switch All bulbs are fused independently Fuse numbers F18 F19 F20 and F21 are used You will notice that the dim circuit T 56b remain on with the headlights Components M35 and M36 are headlamp adjustment motors Laws and Regulations Headlights must be kept in proper alignment aim and condition according to the NCT requirements for Headlamp Condition and Aim Aux Lamps Condition and Aim Fog Lights Fog lights are used with other vehicle lighting in poor weather such as thick fog driving rain or blowing snow Because fog is made up of water droplets suspended in the air it can reflect headlights back into your eyes at night In such conditions fog lights can help drivers see further ahead and illuminate the road s edges at reasonable speeds and are used with park lights instead of headlights Fog lights will normally be wired with a relay They may be wired to work only with park lights and to turn off when headlights are used The schematic diagram on the following page shows a conventional fog light circuit According to the DIN 72552 they are number 55 The front lamps E14 and E15 are switched by relay K2 The earth for this relay is through the headlight filament which means th
3. Correctly strip an electrical wire and connect a solderless connector 3 videos to help deliver section Personal Safety Whenever you perform a task in the workshop you must use personal protective clothing and equipment that is appropriate for the task and which conforms to your local safety regulations and policies Among other items this may include e Work clothing such as coveralls and steel capped footwear e Eye protection such as safety glasses and face masks e Far protection such as earmuffs and earplugs e Hand protection such as rubber gloves and barrier cream If you are not certain what is appropriate or required ask your instructor Heavy Vehicle Mechanic Phase 2 31 Revision 2 0 December 2013 Module 7 Unit 1 Basic Vehicle Wiring Safety Check e Never use a sharp blade or knife to remove insulation You can cut yourself seriously if the blade slips e Wire stripping pliers have sharp edges and require a tight grip Do not trap your skin between the jaws otherwise you risk a severe cut e When removing the insulation from wire push away from you rather than towards you e Make sure that you understand and observe all legislative and personal safety procedures when carrying out the following tasks If you are unsure of what these are ask your instructor Points to Note e An insulating layer of plastic covers electrical wire used in automotive wiring harnesses e When electrical wire is
4. This is a practical task Please refer to your instructor 22 0 Diagnosing Electrical Circuits Practical Task This is a practical task Please refer to your instructor Heavy Vehicle Mechanic Phase 2 29 Revision 2 0 December 2013 Module 7 Unit 1 Basic Vehicle Wiring 23 0 The Effect of Wrong Fuse or Bulb 23 1 Fuses Fuses and circuit breakers are designed to break the circuit if current flow is excessive The most common kinds are fuses fusible links and circuit breakers They are all rated in amperes Their ratings are usually marked on them It is important to fit the correct size of fuse To small a rating will not allow enough current to flow in the circuit and too large a rating may not protect the circuit properly Fuses are typically used in lighting and accessory circuits where current flow is usually moderate Changing the wattage of the bulb te incorrect bulb type will alter the current required If a higher wattage bulb is inserted this could lead to over loading of the electrical system and the possibility of a fire starting A fusible link is typically placed near the battery and except for the starter motor it carries the current needed to power an individual circuit or a range of circuits Heavy Vehicle Mechanic Phase 2 30 Revision 2 0 December 2013 Module 7 Unit 1 Basic Vehicle Wiring 24 0 Crimped Joints on Light Cables 24 1 Stripping Wire Insulation Preparation and Safety Objective
5. 17 0 Location and Voltage Drops on the Earth Connections 26 18 0 Tungsten Halogen and Xenon Bulbs es 26 Eo a Si NP 26 ba Amnon HD eis reliiio M 28 TO VN Fan I Sst seats E EEE EEA E EN SN DD iot UU MES 28 20 0 NCT DoT VIM Regulations for Condition of Lamps 29 20 1 NCT Body Wiring and Lighting Circuit Requirements 29 I dTocusino a DES aucune sone menie ovr di mM E reto E DUE 29 2200 DWidenosine Electrical CIEGUIES qct rtr tron dnk eterni nemdEr taro nb st ez onn Sa HG SAnAS 20 290 The DHocbor Wrong DUE o DO seneea s asneasosaaisadgealasaisaseaihainnenaeaii sasas isinii 30 PONENS c 30 24 0 Crimped Joints on Light Cables eere 31 24 1 Stripping Wire Insulation eese esee eee ee eene tnttnttntnna 31 TEASE SI immm mmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmm 33 Faire a di es Cer ra liri EEEE E E EE 33 Checking amp Changing a Headlight Bulb eee 34 Checking amp Changing an Exterior Light Bulb sess 37 Checking Lighting ec Peripheral SY Steins sistsesecevesessscisscoscsevesescavdecesesnsteontnsdesoscsvee 38 Heavy Vehicle Mechanic Phase 2 Revision 2 0 December 2013 Module 7 Unit 1 Basic Vehicle Wiring 1 0 Learning Outcome By the end of this unit each apprentice will be able to
6. Circuit Symbol Function of Component A voltmeter is used to measure Voltmeter voltage An ammeter is used to measure Ammeter current An ohmmeter is used to measure Ohmmeter resistance 11 0 Switch Controlled Fused Lighting Circuits 11 1 Sample Circuit Diagrams Brake Lights Stop or brake lights are red lights fitted to the rear of the vehicle According to the DIN 72552 they are number 54 They are usually incorporated in the taillight cluster although many vehicles have a higher additional stop light mounted on top of the boot lid or on the rear window called a high level stop lamp H 85 in diagram The stop lights are activated whenever the driver operates the foot brake to slow ot to stop the vehicle Heavy Vehicle Mechanic Phase 2 16 Revision 2 0 December 2013 BRAKE LIGHT CIRCUIT Module 7 Unit 1 Basic Vehicle Wiring e doh e Sq e N SLS qu agu iqu g Figure 1 This schematic diagram shows the brake light circuit Figure1 above Switch S13 is the brake pedal switch and the circuit is protected by fuse F13 which is 10 amps Heavy Vehicle Mechanic Phase 2 17 Revision 2 0 December 2013 31 EP12 EP12 EP12 Brake light bulbs Module 7 Unit 1 Basic Vehicle Wiring Park amp Tail Light Circuits For motor vehicles and trailers two red tail lamps operate when the headlight switch is in the park position and the headlight position According to the DIN 72552 they are number
7. Diagnose and rectify faults in basic lighting circuits using wiring diagrams and multi meter Replace bulbs and fuses with the correct type State the effect of fitting a wrong fuse ot bulb Carry out the correct procedure when a fuse blows repeatedly State the lighting regulations and focus head lights accordingly Make up crimped and soldered joints on light and heavy cables Wire a 7 pin truck trailer connector 7 pin male female 12v and 24v types Wire up a set of auxiliaty spot lights on a vehicle Key Learning Points Construction of earth system circuits Drawing of wiring diagrams and symbols of individual components to ISO and DIN standards Colour and number letter coding used by different manufacturers Function types and carrying capacity of fuses fusible links replaceable and re settable Calculate size of fuse required for a circuit Construction of basic head side tail stop reversing light circuits Drawing and construction of oil light temperature and fuel circuits Drawing and construction of horn circuit wiper and indicator circuits Function operation and wiring of relays Method of headlamp focusing bulb replacement and associated hazards Operation and procedure for carrying out tests on printed circuit tail lamps and gas operated headlamps Procedures for checking circuits for shorting open circuit continuity and bad connections in vehicle circuits and associated hazards personal and vehicle compone
8. Phase 2 25 Revision 2 0 December 2013 Module 7 Unit 1 Basic Vehicle Wiring 17 0Location and Voltage Drops on the Earth Connections Practical Task This is a practical task Please refer to your instructor for additional information which is available from the automotive technical manuals 18 0 Tungsten Halogen and Xenon Bulbs 18 1 Light Bulbs A lamp bulb consists of a fine coil of tungsten wire called a filament enclosed in a clear glass envelope from which all air has been removed Passing a current through the filament raises its temperature to a white heat and causes it to give off an incandescent light Removing air from the glass envelope prevents oxidation of the filament when it is in operation and increases the filament life In high wattage bulbs particles of tungsten can boil off the filament even though the air 1s removed and eventually cause filament failure To prevent this the glass envelope is filled with an inert gas such as argon which does not react with the tungsten and this slows the boiling off of the filament In some applications special coated bulbs are fitted this helps prevent yellowing of plastic lenses Heavy Vehicle Mechanic Phase 2 26 Revision 2 0 December 2013 Module 7 Unit 1 Basic Vehicle Wiring All manufactures have procedures for removing and fitting bulbs these should be followed at all times When fitting a halogen bulb is important not to contaminate the surface o
9. Vehicle Wiring 4 4 Consequences of Faulty Electrical Connections Modern vehicles use a number of electrical connectors to join sections of the vehicle harness to vehicle system components Maintaining proper and safe function of these connectors is very important as any corrosion that occurs in ot on them can cause a reduction in voltage and thus a system problem due to insufficient voltage in a particular system Poor connections are often the cause of many automotive electrical system faults because a faulty connection can increase current draw and have an adverse affect on vehicle system operation They are generally water resistant but not waterproof and the use of a pressure washer particularly if solvents are used in the washing process directly on them should be avoided as this can start the deterioration process 4 5 Gold and Tin Coated Terminal Ends Some connectors terminal ends are gold coated plated in order to reduce potential oxidation corrosion and therefore provide a better long term electrical connection between the items being connected together Do not mix gold coated and tin coated connections together as the combination of the different metals will cause electrolysis which will then damage the electrical conductivity of the connection 5 0 Electromagnetic Relays and a Solenoids 5 1 Electromagnetic Relays Relays are switches that are turned on and off by a small electrical current Inside a relay is an ele
10. direct 5 2 Solenoids Solenoid definition linear movement from an electrical sional The modern starter motor is an example of where a solenoid switch works in a similar way to a relay Itis used as a switch where very high amperage is required to start the vehicle When low current power from the lead acid battery is applied to the solenoid usually through a key switch its movement caused by the magnetic effect acting on its centre component pulls out a small pinion gear on the starter l NN motor s shaft and meshes it with the ring gear on the flywheel of the engine The solenoid also closes high current contacts for the starter motor and it starts to run If the engine starts the key switch is released the solenoid is de energised and a spring returns in to the rest position thereby disconnecting the supply from the starter motor and pulling the small gear back off the starter gear Heavy Vehicle Mechanic Phase 2 10 Revision 2 0 December 2013 Module 7 Unit 1 Basic Vehicle Wiring 6 0 Relays in Lighting Circuits Relay function covered in 4 1 7 0 Terminal Designations of a Trailer Wiring Socket Plug 7 1 Trailer Wiring Socket The socket mentioned is the common 12N TYPE This socket is coloured black and houses 7 pins which are numbered 1 to 7 and need to be connected using the correct wiring destinations as follows Front view of trailer socket on vehicle Note Refer to manufactures fitting inst
11. is available from automotive technical manuals Overview A circuit diagram also known as an electrical diagram or electronic schematic is a pictorial representation of an electrical circuit It shows the different components of the circuit and the power and signal connections between the devices Arrangement of the components and interconnections on the diagram does not usually correspond to their physical locations in the finished device Unlike a block diagram ot layout diagram a circuit diagram shows the actual wire interconnects being used although the picture does not have to correspond to what the circuit actually looks like 2 2 Component Identification Group Codes The individual components shown on schematic wiring diagrams can be identified by a Group code and also by a number Then all similar items are described by the same Group letter e g assemblies i e Airbag driver are identified by the letter A switches S all fuses are identified by the letter FP The number ot mathematical figure after the letter will identity the circuit to which that fuse belongs to Light bulbs are given the letter E motors M and all relays K again the number after the letter will identify the circuit to which that component belongs to The full list of these is available in the Technical support Information 2 3 Connecling Wire Colour Code The colours of the individual connecting wires can be
12. joined to other wires or connected to a terminal the insulation needs to be removed e Wire stripping tools come in various configurations They all perform the same task The type of tool you use or purchase will depend on the amount of electrical wire repairs you perform Step by Step Instruction 1 Choose the correct stripping tool The purpose of a wire stripping tool is to allow you to remove the insulation from around the copper core of a cable without damaging the cable or yourself Never use a knife or other type of sharp instrument to cut away insulation from a cable as it is very easy for these to slip and you can injure yourself Using side cutters or pliers can also be dangerous and these are also less effective as they often cut away some of the strands of wire as well This is known as ringing the wire which effectively reduces the current carrying capacity of the wire 2 Select the correct gauge hole Using the correct tool is much safer and more effective Wire strippers can remove the insulation from different gauges of cable so select the hole in the stripper that is closest to the diameter of the core in the cable to be stripped Heavy Vehicle Mechanic Phase 2 32 Revision 2 0 December 2013 Module 7 Unit 1 Basic Vehicle Wiring 3 Cut the insulation Place the cable in the hole and close the jaws firmly around it to cut the insulation If you have selected the right gauge then this will cut through the insulatio
13. over longer distances than standard headlight systems NCT regulations specify the limitations in relation to the positioning of driving lights There are many types of driving lights available They come in different sizes shapes and varying bulb wattage Indicators The turn signal indicators are visual signalling devices to indicate the intention to turn Once they are activated they continue until the switch is cancelled either by the operator or by a cancelling mechanism in the switch The cancelling mechanism operates after a turn has been completed and the steering wheel is returned to the straight ahead position Heavy Vehicle Mechanic Phase 2 22 Revision 2 0 December 2013 Module 7 Unit 1 Basic Vehicle Wiring Ihe circuit consists of e battery e fusible links and fuses e ignition switch e flasher unit e athree position switch used as the direction indicator switch e lights at the front and rear of the vehicle e pilot lights mounted in the instrument cluster to indicate to the driver which way the switch has been operated e wiring to connect all of the components e the ground circuit to return the electrical current to the battery If the indicator switch is turned to indicate a right hand turn current from the battery flows through the fusible link to the ignition switch where it is directed through a fuse to the flasher unit 12 0Relay Controlled Auxiliary Lighting Circuits Practical Task This is a
14. TRADE OF HEAVY VEHICLE MECHANIC PHASE 2 Module 7 Basic Vehicle Wiring Electric Motors and Computers UNIT 1 Basic Vehicle Wiring Module 7 Unit 3 Computets Table of Contents Ie ao COULCOTIIG meee ern eniti err rrr rrr tnt rr gh gen er er SUM EN 1 1 1 Ty a IIe OTS va cece ects E E NE OA E 1 20 Schematic Electncal Witihg Dantan esee ee retento einer enero ione 2 ZU Layout ot WC tto EC UNES cuasuuptecesiedlisn deep eon oiie as iia oiin enoii 2 2 12 Component Identification Group Codes esses 4 2 9 Connecting Wire Colour Code a accsesecssicebscadeospecnseatesuansataystweateuinassocssunaiel 4 2 4 Example Wiring Diagrams eet retta ertet iip epenton aes donsteecsuatevseuestacsutaees B 2 5 Symbols and Codes Used in the Example Diagrams D 3 0 Primaty Terminal Ies CH O eerrereerne tore eer en rare ner SEU HUS mene rr 5 3 1 Electrical Connection DIN INUPIDEES useeciee aborto rsen etti cionis 6 4 0 Electrical Connectors and Their Function eee 7 4 1 Physical Requirements of Electrical Connections sesss 7 4 2 Operational Requirements of Electrical Connections T 4 3 Service Requirements of Electrical Connectors eese 7 4 4 Consequences of Faulty Electrical Connections essss 8 4 5 Gold and Tin Coated Terminal Ends us ieerretect toti Seen timetis 8 5 0 Electromagne
15. at the fog lamps will only operate when the headlights are off Fuse F3 protects the relay and fuse F36 protects the lighting circuit Heavy Vehicle Mechanic Phase 2 20 Revision 2 0 December 2013 Basic Vehicle Wiring Module 7 Unit 1 d3 Ld3 Le g g Ar 6V 8v AS FEE RERA 19 a lo 3 I n ums ail t tci m m AN I s P 8 ls I I I I I i I I YS IR e ko T a 8 Is G I oO E E m a m eee ee ee s k Fi 98 lo a ZOLWOSLWISZ cH v e S X 0 LINDAID dNV1 904 Q3TIOHLNOO AV 13H 21 Revision 2 0 December 2013 Heavy Vehicle Mechanic Phase 2 Module 7 Unit 1 Basic Vehicle Wiring Reverse Lights The reversing lights are white lights fitted to the rear of a vehicle They provide the driver with vision behind the vehicle at night and also alert other drivers to the fact that the vehicle is to be teversed When the ignition switch is on and the vehicle is placed in reverse gear current flows from the battery through the ignition switch to the closed reversing light switch on the transmission Electrical current flows across the closed switch to the reversing lights and then returns to the battery by the earth return system Driving Lights Driving lights are used to supplement vehicle headlight systems The driving lights are fitted to the front of the vehicle and provide higher intensity illumination
16. ays etc and all the connectors and terminal connections on the live and earth sides of these circuits Circuits in the vehicle are subjected to the stresses of vibration moisture and temperature change also the possible corrosion by corrosive fluids and gases Vibration and movement due to thermal expansion also cause small movement that result in friction between any connectors that are simply clamped together 4 2 Operational Requirements of Electrical Connections Therefore electrical connectors must provide as easy a path as is possible for the electrons to leave one side of the connection and enter the adjoined connector The connector must also provide adequate electrical insulation for the current flowing through it and it must prevent entry of moisture and dirt Connections must also be designed so that they can be readily connected or disconnected and yet have a secure locking system 4 3 Service Requirements of Electrical Connectors Electrical connections should not be dismantled and reassembled unless it is absolutely necessary because each movement increases the risk of the frictional resistance affecting the quality of the surface to surface electrical contact It should not be possible to pair incorrect connectors connections together as the implications of this could be most serious the greatest dangers being short circuits and fire Heavy Vehicle Mechanic Phase 2 7 Revision 2 0 December 2013 Module 7 Unit 1 Basic
17. ctromagnet When a small current energizes this electromagnet it attracts an armature blade and closes contact points The large current that the relay is designed to switch on or off can then flow across these points As long as the small switching current flows through the relay coil the much larger current will flow through its contact points The function of a relay in the lighting circuits is to reduce the current demand on the control switch Heavy Vehicle Mechanic Phase 2 8 Revision 2 0 December 2013 Module 7 Unit 1 Basic Vehicle Wiring 0 AMPS Uv AMP h i I p These contacts can be either normally open normally closed or change over contacts e Normally open contacts connect the circuit when the relay is activated the circuit is disconnected when the relay is inactive Normally closed contacts disconnect the circuit when the relay is activated the circuit is connected when the relay is inactive e Change over contacts control two circuits one normally open contact and one normally closed contact Heavy Vehicle Mechanic Phase 2 9 Revision 2 0 December 2013 Module 7 Unit 1 Basic Vehicle Wiring 30 86 8587 Switching relay Earth end of winding to ground or negative Switching relay Positive start of winding Switching relay Output to consumer eg driving lamp Switching relay Alternative output 1st output break side Positive supply Input from battery terminal
18. d test Replace the cover and test it again Checking Lighting amp Peripheral Systems Preparation and Safety Objective Check peripheral lighting systems TL ae Heavy Vehicle Mechanic Phase 2 38 Revision 2 0 December 2013 Module 7 Unit 1 Basic Vehicle Wiring Personal Safety Whenever you perform a task in the workshop you must use personal protective clothing and equipment that is appropriate for the task and which conforms to yout local safety regulations and policies Among other items this may include e Work clothing such as coveralls and steel capped footwear e Eye protection such as safety glasses and face masks e Far protection such as earmuffs and earplugs e Hand protection such as rubber gloves and barrier cream e Respiratory equipment such as face masks etc Safety Check Make sure that you understand and observe all legislative and personal safety procedures when carrying out the following tasks If you are unsure of what these are ask your instructor Points to Note e Be sure to work in a systematic manner or you could miss a faulty bulb ot another component e A vehicle may have warning lights that will activate only if that circuit is in use You may need to turn that circuit on to see the warning light If you are unsure of where these are ask your instructor Step by Step Instruction 16 Check instrumentation in a darkened area turn on the ignition The dash war
19. d with a DVOM Heavy Vehicle Mechanic Phase 2 35 Revision 2 0 December 2013 Module 7 Unit 1 Basic Vehicle Wiring Touching a new halogen bulb with your fingers can leave some greasy residue from your fingers on the outer surface This can cause the bulb to burn out vety quickly If you inadvertently touch the bulb clean it with an alcohol based substance Step by Step Instruction 6 10 Check headlight operation Assessing headlight operation is always best carried out in a low light environment Switch the vehicle headlights on to low beam and then switch to high beam Check that the main beam indicator on the instrument panel is operating Note the change in the intensity of the lights If one of the lights does not operate that headlight will need replacement Identify headlight type Determine the type of lamp fitted to the vehicle and obtain a replacement Many vehicles today are equipped with halogen type headlights These are twice as powerful as older sealed beam units and need to be handled carefully Always follow the manufacturer s handling instructions Access the lamp socket Unplug the electrical connector at the back of the lamp unit On most vehicles it is not necessary to remove the lamp unit from the vehicle Unscrew the bulb retaining ring Remove and replace the old bulb Remove the old bulb and replace it with the new one Handle the new bulb only by its base or if supplied by the card cover It i
20. e able to see the road ahead for approximately 100 meters compared to about 60 meters for a halogen system In comparison with halogen lights HID headlights can be up to 3 times brighter are more efficient in converting electrical energy into light energy have a longer service life and the light colour is whiter or closer to daylight They operate on a gas discharge bulb system and consist of a light bulb ballast and special high voltage circuitry HID headlights systems do not use a filament in the bulb They have the inert gas Xenon inside the bulb with two electrodes that have an air gap between them in a glass tube A high voltage is applied between the electrodes This causes an arc to form which vaporizes the gases and solids so they emit a bright light The voltage required to strike and maintain the arc is very high typically up to 20 000 volts Therefore when workings on these systems refer to manufactures procedures at all times 19 0Servicing Lamps Practical Task This is a practical task Please refer to your instructor Heavy Vehicle Mechanic Phase 2 28 Revision 2 0 December 2013 Module 7 Unit 1 Basic Vehicle Wiring 20 0 NCT DoT VIM Regulations for Condition of Lamps 20 1 NCT Body Wiring and Lighting Circuit Requirements Please refer to the current NCT reference manual item No s 26 to 34 inclusive for NCT requirements for Passenger Vehicle lighting systems 21 0Focusing Headlights Practical Task
21. ehicle Wiring Personal Safety Whenever you perform a task in the workshop you must use personal protective clothing and equipment that is appropriate for the task and which conforms to yout local safety regulations and policies Among other items this may include e Work clothing such as coveralls and steel capped footwear e Eye protection such as safety glasses and face masks e Far protection such as earmuffs and earplugs e Hand protection such as rubber gloves and barrier cream e Respiratory equipment such as face masks etc Safety Check Make sure that you understand and observe all legislative and personal safety procedures when carrying out the following tasks If you ate unsure of what these are ask your instructor Points to Note e There are many types of headlight bulbs available Always make sure that you replace a bulb with one of exactly the same type Otherwise change both lights at once so they always show the same intensity in lumens e Sealed beam units require that the whole unit be replaced when one filament has failed If the reflector in the lamp unit shows signs of internal blistering that also indicates that you must change the unit e If both lights operate but are not bright when switched on start the engine to see if this solves the problem The battery may be in a poor state of charge Another explanation 1s that the system may have a bad ground connection This would have to be checke
22. f the bulb with your hand as this will result in premature failure of the bulb The focusing of the headlights is also advisable after fitting new headlight bulbs to ensure they are properly aligned to current NCT regulations Bulb Information All bulbs have letters and numbers stamped on the bulb which indicate the power consumed by bulb operation at the nominal operating voltage For instance in a 12V 21W bulb the filament will consume 21 watts of power when 12 volts is applied across the filament While the wattage is not necessarily an indication of light output it can be generally assumed that the higher the wattage the greater the light output will be If a higher wattage bulb is inserted than what is recommended this could lead to more heat been generated and the possibility of a fire starting The common bulbs used in automobiles are e Festoon bulbs used in many interior lights e Bayonet connectors used in circuits lighting for park lamps stop lamps tail lamps number plate lamps some early headlamps e Wedge bulb use in many dash clusters Heavy Vehicle Mechanic Phase 2 27 Revision 2 0 December 2013 Module 7 Unit 1 Basic Vehicle Wiring 18 2 Xenon HID Headlights High Intensity Discharge or HID lights can be recognized by their extremely bright white or bluish light They provide the motorist with better illumination than other types of lights HID lights improve visibility Drivers using HID lights ar
23. identified by letter code that may be an English or German language abbreviation of the actual wire colour The principal differences are e White ws Weiss e Black sw Swartz e Red rt Rote e Yellow ge Gelb The full list is available in the Technical support Information Heavy Vehicle Mechanic Phase 2 4 Revision 2 0 December 2013 Module 7 Unit 1 Basic Vehicle Wiring 2 4 Example Wiring Diagrams The example wiring diagrams beginning on page 17 are those of a Volkswagen Golf 1 4 petrol 1997 06 engine code AHW This first diagram is broadly representative of range of manufacturer s schematic diagrams A special feature of this diagram is the terminal identification code X This terminal is the equivalent of terminal No 75 accessories this means that it is live with the ignition on but it is switched off during engine cranking This is to retain maximum battery voltage for engine cranking 2 5 Symbols and Codes Used in the Example Diagrams Some of the symbols used in these diagrams are not strictly to DIN standard but instead they are a pictorial representation of the individual components e g the dim lamps are indicated differently to the main beams This is the system used by Autodata and it is designed help you to read or interpret diagrams from all motor manufacturers The following diagrams in this unit are an attempt to lift or highlight individual circuits from an overall diagram Y
24. ircuit Symbol Function of Component Sa pe probe pide da Wire Ds one part of a circuit to another A blob should be drawn where wires are connected joined but it is sometimes omitted Wires Wires joined connected at crossroads should be staggered slightly to form two T junctions as shown on the right In complex diagrams it is often necessary to draw wires crossing even though they are not connected I prefer the hump symbol shown on the right because the simple crossing on Wires not joined the left may be misread as a join where you have forgotten to add a blob Heavy Vehicle Mechanic Phase 2 13 Revision 2 0 December 2013 Module 7 Unit 1 Basic Vehicle Wiring Power Supplies Component Circuit Symbol Component Circuit Circuit Symbol Function of Component Supplies electrical energy The larger terminal on the left is positive A single cell is often caled a battery but strictly a battery is two or more cells joined together Supplies electrical energy A battery is more than one cell Bae poe The latger terminal on the left is positive A safety device which will blow Fuse ELALLL melo if the current flowing mu through it exceeds a specified value Earth A connection to earth It is also Ground known as ground Output Devices Lamps Motor Component Circuit Symbol i Circuit Circuit Symbol Function of Component A transducer which converts electrica
25. l energy to light This Lamp indicator symbol is used for a lamp providing illumination for example a car headlamp A transducer which converts electrical energy to kinetic energy motion Heavy Vehicle Mechanic Phase 2 14 Revision 2 0 December 2013 Module 7 Unit 1 Basic Vehicle Wiring Circuit Symbol Function of Component SPST Single Pole Single Throw On Off 8 nk m h An on off switch allows current to flow alk er only when it is in the closed on position SPDT Single Pole Double Throw A 2 way changeover switch directs the flow of current to one of two routes according to its position 2 way Switch SPDT Dual On Off Switch DPST DPST Double Pole Single Throw iili Reversing Switch DPDT Double Pole Double Throw DPDT Resistors Function of Component Circuit Symbol Component A resistor restricts Resistor the flow of current This type of vatiable resistor with 2 contacts a rheostat is usuall Variable Resistor 1s usually used to control Rheostat current Examples include adjusting dash panel brightness This type of vatiable resistor ith 2 contacts Variable Resistor M E a potentiometer is Potentiometer usually used to control voltage e g fuel gauge Heavy Vehicle Mechanic Phase 2 15 Revision 2 0 December 2013 Module 7 Unit 1 Basic Vehicle Wiring Meters and Oscilloscope Component Circuit Symbol Component Cireuit
26. n but not through the copper core Only remove as much insulation as is necessary to do the job Too little bare wire may not achieve a good connection and too much may expose the wire to a potential short circuit with other circuits or to ground Removing more than 1 2 centimetres of insulation at a time can also stretch and damage the core 4 Remove the insulation Some strippers automatically cut and remove the insulation Others just make the cut and hold the cable tightly and you need to pull firmly on the wire to remove the insulation and strip out the copper core To keep the strands together give them a light twist Task Sheets Aiming Headlights Preparation and Safety Objective Use a headlamp adjuster unit to aim headlights Personal Safety Whenever you perform a task in the workshop you must use personal protective clothing and equipment that is appropriate for the task and which conforms to yout local safety regulations and policies Among other items this may include e Work clothing such as coveralls and steel capped footwear e Eye protection such as safety glasses and face masks e Far protection such as earmuffs and earplugs e Hand protection such as rubber gloves and barrier cream e Respiratory equipment such as face masks etc Safety Check Make sure that you understand and observe all legislative and personal safety procedures when carrying out the following tasks If you are unsure of what these a
27. ning lights should be displayed Start the engine If any warning light stays on when the engine is started it could indicate a problem in one of the car s safety or mechanical systems If you are unsure about what any of the warning lights mean consult the manufacturer s manual 17 Check the car horn Make sure the car horn is working If the horn 1s not working locate it under the hood with the help of the manufacturer s manual Check the wiring to make sure there is a good contact If necessary use a DVOM to isolate the fault 18 Check rear lights have someone stand behind the vehicle to report any problems and then turn the ignition on Switch on the park lights and tail lights Do the same for left and right turn indicator lights Depress the brake pedal to make sure the brake lights work Heavy Vehicle Mechanic Phase 2 39 Revision 2 0 December 2013 Module 7 Unit 1 Basic Vehicle Wiring 19 Check front lights with somebody in front of the vehicle make sure the high and low headlight beams the park lights and the turn indicators are all working properly 20 Check interior lights with the interior light switch in the correct position open the driver s side door to make sure the interior lights work If any of these lights do not operate you may need to replace a bulb or a fuse Check the fuse first using a DVOM to check continuity If the fuse 1s at fault you should report this to your instructor as there could be a mo
28. nt hazards Soldering and crimping procedures fluxes connectors Hazards Wiring of vehicle trailer suzie connectors and auxiliary spot lights Heavy Vehicle Mechanic Phase 2 1 Revision 2 0 December 2013 Module 7 Unit 1 Basic Vehicle Wiring 2 0 Schematic Electrical Wiring Diagram 2 1 Layout of Electrical Circuits The layout of electrical circuits and their components are shown as diagrams made up of symbols and connecting lines Being able to read a circuit diagram is important when trying to trace and correct a fault in an electrical system However all manufacturers do not use the exact same symbols codes or terminal numbers but for you to get a successful beginning at reading wiring diagrams it is best to follow one common system The system described here is based on the European DIN standard that generally has current flowing from top Terminal No 30 to the bottom earth Terminal No 31 and from left to right Refer to the manufacturer s service manual for specific details on how to read a particular circuit diagram Heavy Vehicle Mechanic Phase 2 2 Revision 2 0 December 2013 Module 7 Unit 1 Basic Vehicle Wiring 33170 5 z i S E Volkswagen Golf 1 4 petrol 1997 06 engine code AHW Reproduce d courtesy of Autodata Heavy Vehicle Mechanic Phase 2 3 Revision 2 0 December 2013 Module 7 Unit 1 Basic Vehicle Wiring Note For training and testing purposes diagrams and information
29. ou should study each diagram carefully and then when you feel confident go further and practice locating and tracing these circuits in other manufacturer s similar diagrams Remember the aim of this exercise is for you to have the ability to develop and construct these circuits yourself 3 0 Primary Terminal Designation The purpose of the terminal designation system for automotive electrical systems is to enable correct and easy connections of the conductors to the various devices especially in the event of repairs and equipment replacement DIN 72552 is a DIN standard for Automobile electric terminal numbers standardizing almost every terminal in an automobile with a number code If the number of terminal designations is not sufficient multiple contact connections the terminals are consecutively numbered using numbers or letters whose representations of specific functions are not standardized Heavy Vehicle Mechanic Phase 2 5 Revision 2 0 December 2013 Module 7 Unit 1 Basic Vehicle Wiring 3 1 Electrical Connection DIN Numbers Terminal Designations Excerpts from DIN Standard 72 552 these terminal designations do not identify the conductors because device with different terminal designations can be connected at the two ends of each conductor If the number of terminal designations is not sufficient multiple contact connections the terminals are consecutively numbered using numbers or letters whose representations of
30. practical task Please refer to your instructor for additional information which is available from the automotive technical manuals 13 0 To Connect a Trailer Light Assembly Practical Task This is a practical task Please refer to your instructor Heavy Vehicle Mechanic Phase 2 23 Revision 2 0 December 2013 Module 7 Unit 1 Basic Vehicle Wiring 14 0Diagram of Basic Standard Circuits Practical Task This is a practical task Please refer to your instructor for additional information which is available from the automotive technical manuals Examples of in section 10 1 15 0 The Term BUS as Used in Automotive Electrical Systems 15 1 BUS Explained In automotive systems the term bus can connect several control units or devices together over the same set of wires A comparison can be made to a highway with two way traffic and traffic emerging onto the highway from different locations Access to the highway is controlled by traffic lights can bus This system 1s referred to as a Controlled Area Network BUS or CAN BUS CAN stands for Controller Area Network meaning that control units are networked and they interchange data It uses two thin wires to connect or multiplex all the control units and their sensors to each other The advantage of a multiplex network is that it enables a decreased number of dedicated wires for each function and therefore a reduction in the number of wires in the wiring harness reduced sy
31. re ask your instructor Heavy Vehicle Mechanic Phase 2 33 Revision 2 0 December 2013 Module 7 Unit 1 Basic Vehicle Wiring Points to Note Check manufactures settings and current NCT settings If you are unsure of what these are ask your instructor Refer to the manufacturer s manual for specific information regarding headlight aiming They may also suggest that a load be placed in the vehicle Step by Step Instruction l Check tire pressures Make sure the car 1s on an even and level surface and that the tires are inflated properly Over loading the rear of the vehicle can alter the alignment so make sure the check 1s done according to the manufacturers loading recommendations Position vehicle Move the vehicle into the correct position in relation to the headlamp aligner unit following the equipment manufacturer instructions Check low beam settings turn the headlights on to a low beam setting Check readings against manufactures settings Check high beam settings the high beam should be cantered falling on the intersections of the horizontal and vertical marks Adjust headlight alignment If necessary locate the adjustment screws on the headlight and turn them so the lights point to the correct places Checking amp Changing a Headlight Bulb Preparation and Safety Objective Check and change a headlight bulb Heavy Vehicle Mechanic Phase 2 34 Revision 2 0 December 2013 Module 7 Unit 1 Basic V
32. re serious fault in the vehicle s wiring system Heavy Vehicle Mechanic Phase 2 40 Revision 2 0 December 2013 SOLAS An tSeirbh s Oideachais Lean naigh agus Scileanna Further Education and Training Authority 27 33 Upper Baggot Street Dublin 4
33. ructions at all times If fitting a trailer socket on a vehicle that has a can bus system it is important to use the manufactures trailer socket as this will comply with the necessary requirements for that vehicle Heavy Vehicle Mechanic Phase 2 11 Revision 2 0 December 2013 Module 7 Unit 1 Basic Vehicle Wiring 8 0 The Basic Multiple Position Switch Symbol Covered in next section 9 0 Basic Dual Triple Branch Parallel Circuits Practical Task Please refer to your instructor for additional information which is available from the automotive technical manuals Examples of in section 10 1 Component _ Circuit Symbol Function of Component SPST Single Pole Single Throw On Off Switch An on off switch allows current to flow SPST only when it is in the closed on position SPDT Single Pole Double Throw 2 way Switch A 2 way changeover switch directs the SPDT flow of current to one of two routes accotding to its position Dual On Off Switch DPST Double Pole Single Throw DPST DPDT Double Pole Double Throw Heavy Vehicle Mechanic Phase 2 12 Revision 2 0 December 2013 Module 7 Unit 1 Basic Vehicle Wiring 10 0Basic Schematic Wiring Diagrams 10 1 Automotive Electrical Symbols The following are some examples of the symbols used in circuit diagrams The actual layout of the components is usually quite different from the circuit diagram Wires and Connections Component Circuit C
34. s very important that you never touch the surface of the bulb with your fingers as this will cause it to burn out very quickly Replace the headlight unit and test Replace the unit and the retaining ring or bulb assembly and then re plug the connector Switch on the lights again to confirm that they are both operating correctly Heavy Vehicle Mechanic Phase 2 36 Revision 2 0 December 2013 Module 7 Unit 1 Basic Vehicle Wiring Checking amp Changing an Exterior Light Bulb Preparation and Safety Objective Check and change an extetior light bulb Personal Safety Whenever you perform a task in the workshop you must use personal protective clothing and equipment that is appropriate for the task and which conforms to yout local safety regulations and policies Among other items this may include e Work clothing such as coveralls and steel capped footwear e Eye protection such as safety glasses and face masks e Far protection such as earmuffs and earplugs e Hand protection such as rubber gloves and barrier cream e Respiratory equipment such as face masks etc Safety Check Make sure that you understand and observe all legislative and personal safety procedures when carrying out the following tasks If you ate unsure of what these are ask your instructor Points to Note e Make sure that the fuses are in good condition before attempting to change a bulb in a circuit that has more than one bulb such as the t
35. specific functions are not standardized 15 Switched downstream of battery output of ignition driving switch Battery Input from battery terminal direct Return line to battery battery terminal or ground direct Turn Signal Flasher 49 and 49a 49b and 49c All terminal no s 49 have to with the turn signal indicators etc Starter Starter control ignition switch to the starter switch Brake lamp Lighting Fog lamps Headlamp system High beam and Main beam indicator lamp Low beam 58 Side marker lamps tail lamps license plate lamps and instrument panel lamps 58L Side matker lamp left Side marker lamp right Alternators and voltage regulators Alternator charge indicator light Switching Relay Output actuator end of winding to ground or negative Start of winding 87 Output to the load from terminal 30 87a Normally closed contact Heavy Vehicle Mechanic Phase 2 6 Revision 2 0 December 2013 Module 7 Unit 1 Basic Vehicle Wiring DIN Deutsches Institut f r Normung is the German national organization for standardization and is that country s ISO member body Additional information is available from the automotive technical manuals 4 0 Electrical Connectors and Their Function 4 1 Physical Requirements of Electrical Connections Electrical circuits require connections to assemble or join the power supply to the desired load Complex circuits will have switches fuses possibly rel
36. stem cost and weight improved reliability serviceability and installation In addition common sensor data such as vehicle speed engine temperature etc are available on the network so data can be shared thus reducing the number of sensors Also networking allows greater vehicle content flexibility because functions can be added or modified through software changes A diagnostic tool can be connected to the CANBUS to extract operational information to assist in diagnosis and fault finding Heavy Vehicle Mechanic Phase 2 24 Revision 2 0 December 2013 Module 7 Unit 1 Basic Vehicle Wiring 16 0 In Vehicle Network Developments 16 1 Networking amp Multiplexing Even the most basic vehicles include many electronically controlled systems If each electronic system had its own ECU harness and sensors the weight of the added components would negate any efficiency it provided A vehicle multiple electronic systems could require over 1 6 Kilometres of insulated wiring consisting of around 1000 individual wires and many terminals One solution to the problem is the use of a system that integrates sensors into a common wiring harness by combining all the individual systems where possible into a multiplexed serial communications network so they can share the information An added advantage is that it saves weight as it allows different systems to share sensors and reduces complexity of stand alone systems Heavy Vehicle Mechanic
37. tic Relays and a Solenoids cessus 8 5 1 iSi rcrenrojep tese sil ai iol m 8 5 2 s aici M ere 10 6 0 Ie Hyp hele Lontan CDEGIIUS cte stuspputsienki ge Rus reter Und oS cee errr erste errr er 11 7 0 Terminal Designations of a Trailer Wiring Socket Plug 11 Tal Trader WA e Ct E E A EA 11 8 0 The Basic Multiple Position Switch Symbol sss 12 9 0 Basic Dual Triple Branch Parallel Circuits sss 12 10 0 Basic Schematic Wiring Diagrams ssc ciacescentsantvennaannanincainentsaonsenatantdeeicavia 13 10 1 Automotive Electrical Symbols caster eaatencerstecnenaeeacsorarneseecaesenacspesretean 13 11 0 Switch Controlled Fused Lighting Circuits eese 16 DLE Sampe tcu DEOS wwwwwwuwwvwvvwvwvwwvwvvvvvv 16 Heavy Vehicle Mechanic Phase 2 Revision 2 0 December 2013 Module 7 Unit 3 Computets 12 0 Relay Controlled Auxiliaty Lighting CHCUIUSu a picuri cottidie Diis 23 130 To Connect a Trailer Light Ss Cty e uensisqetexptts pnt EUpaae nth niue onete qe 23 14 0 Diagram of Basic Standard Circuits eene 24 15 0 The Term BUS as Used in Automotive Electrical Systems 24 P IESU BSEC s me p iu dide i rT uu UN quam dU 24 16 0 In Vehicle Network Developments accessit rata pite oom b retos 25 161 Networking amp Multiplexing tats cc oer seston cen senesoeestornansaeeee 25
38. urn sional circuit If none of the bulbs are working there may be a bigger problem to resolve e Many light bulbs have more than one filament inside them These bulbs normally have offset pins to ensure proper locking in the socket Be sure to look carefully at the bulb you are replacing to make sure you do not try to force the bulb in the wrong way Heavy Vehicle Mechanic Phase 2 37 Revision 2 0 December 2013 Module 7 Unit 1 Basic Vehicle Wiring Some bulbs have a coloured glass envelope that enables them to be used with a clear lens If you replace a bulb of this type make sure that you replace it with one of the same colour Step by Step Instruction 11 LA 13 14 15 Access the bulb Determine the method used to secure the lamp unit or lens cover and remove the cover to expose the bulb If no screws are found on the lens cover it may be necessary to remove the entire assembly to access the bulb Remove the bulb If the bulb is pin mounted gently grip the bulb and push it inwards Turn the bulb in a counter clockwise direction and remove it from the bulb holder Check bulb holder for corrosion Inspect the bulb holder to make sure there is no corrosion If there 1s clean it with abrasive tape Insert the new bulb Insert the new bulb into the bulb holder depress it fully turn it clockwise and release it Make sure the bulb is secure and test its operation by switching it on and off Replace cover an
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