LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1LV02 kỹ năng nền tảng vấn đề 1
kap all covers 6/9/03 9:48 am Page Student Workbook LV02 Foundation Skills LV02/SWB Student Workbook for Technical Certificates Light Vehicle Maintenance and Repair MODULE LV02 FOUNDATION SKILLS Contents Page 3 3 Common Hand Tools: Air tools Air ratchet Air gun Air drill Hand spanners, wrenches and sockets Special sockets Torque wrenches Pliers and grips Files and filing Using the file Hacksaw Drills and drilling Screw cutting Taps Dies Thread sizes Special service tools Progress check 6 7 10 10 11 11 12 13 Measurement: Length Area Volume Exercise 14 14 15 16 17 Pressure: What is pressure? 18 18 Page … Pressure units Pressure in liquids Progress check 20 21 22 Measuring Equipment: Micrometer Using the micrometer Reading the micrometer Vernier calliper Dial gauge Feeler gauge Progress check 23 23 24 25 26 27 28 29 Principles of Electricity: What is electricity? The principles of electricity Positively charged body Conductors, semi-conductors and Insulators How is flow of electricity measured? Voltage Electrical resistance Ohm’s Law Transposing Ohm’s Law Watts Progress check 30 30 31 32 (Cont.) -1Copyright © Automotive Skills Limited 2003 All Rights Reserved LV02: Foundation Skills Issue 33 33 34 35 36 37 38 39 Page Electrical Measurement: Multimeters Unit multipliers Multimeter use Progress check Types of circuit Series Parallel Series parallel Progress check Electrical wiring diagrams Japanese manufacturers European manufacturers 40 40 41 41 43 44 44 44 45 46 47 47 50 Locking and Securing Devices: Bolts and screws Nuts and washers Chemical thread locking Progress check 51 51 53 54 55 ……… Inspection and Fault-finding Techniques: Diagnosis techniques Driver interrogation Gathering information Visual inspection Formulating your diagnostic strategy Progress check -2Copyright © Automotive Skills Limited 2003 All Rights Reserved LV02: Foundation Skills Issue Page 56 56 56 57 57 58 60 Common Hand Tools Air tools A technician’s hand tools are as important to him as surgical instruments are to a surgeon Without a good selection and perhaps more importantly, a high level of skill with respect to use and application, a technician cannot the job Let us study a few of the more common hand tools that a technician is likely to require Air ratchet This tool lends itself particularly well to the removal of screws used in large quantities to secure components, such as those found holding a sump It is rare for such a tool to have any sort of torque regulation, so its use for refitting screws should be avoiding or carried out with a great deal of care – final tightening should always be carried out with a torque wrench (studied later in this chapter) Air gun This does a similar job to the air ratchet but is generally capable of generating far more torque The torque output is normally adjustable through a knurled knob Unlike the air ratchet, air guns are designed for use with two hands and are produced with ⅜ inch, ½ inch and even inch drives The latter is a pretty fearsome piece of kit and deserves some respect! -3Copyright © Automotive Skills Limited 2003 All Rights Reserved LV02: Foundation Skills Issue Air drill This can be used to carry out typical drilling operations and is powered by air pressure like the other tools described here One key benefit of all air tools is safety From a safety aspect, they win hands down when compared to electrical power tools The reason is clear when you consider that a vehicle technician often has to work in damp conditions Hand spanners, wrenches and sockets Spanners (or wrenches) are the technician’s ‘bread and butter’ tools These tools facilitate the removal of the nuts and bolts that secure components to a vehicle to enable repair or access There are many different types of spanners available, designed for a multitude of tasks but four of the most commonly used are shown above Ring spanners provide more contact between the tool and the nut or bolt and their use is far less likely to result in damage or ‘rounding off’ Open-ended spanners should be used only when a ring spanner is not suitable -4Copyright © Automotive Skills Limited 2003 All Rights Reserved LV02: Foundation Skills Issue Most types of spanners have cranked ends to help location with the flats of a nut or bolt, where access is tight and the nut or bolt can only be moved by a small amount each time Sockets are also designed for aiding the removal of nuts and bolts Unlike a spanner, they cannot be used on their own but have to be used in conjunction with a secondary tool such as a ratchet or perhaps a knuckle bar or speed brace The ‘spanner priority’ should be observed when deciding which tool is best suited for the removal of a nut or bolt Other factors permitting, the choice should be in the following order – socket, ring spanner, open-ended, and finally an adjustable spanner if all else has failed! Sockets are available in varying sizes and shapes such as shallow, standard, deep, six point and twelve point Strengthened sockets (impact sockets) must always be used with air tools Standard sockets not have sufficient strength and could shatter Special sockets Standard hexagon head bolts are rarely found in areas where there is little room to spare and where large amounts of torque are required It is more common to find multi-spline, Torx or Allen key female-headed bolts (discussed later in this workbook) -5Copyright © Automotive Skills Limited 2003 All Rights Reserved LV02: Foundation Skills Issue Torque wrenches A torque wrench is designed to facilitate the accurate and consistent tightening of nuts and bolts They can also be used for carrying out adjustments where a given amount of resistance to rotation is required on an assembly (pre-load) Each use requires a different type of torque wrench - a ‘click type’ for tightening nuts and bolts and a ‘torque meter’ for pre-load adjustment The picture above shows a click type in use It is bad practice to click the wrench several times when tightening a bolt One click is sufficient If more than one click is heard, the bolt could be over-tightened Pliers and grips Pliers can be used for a variety of tasks and there are many different types available Combination pliers are the most common and can be used to carry out any number of operations where increased grip and leverage are required Generally speaking, side cutters can a large number of jobs adequately, but if there is a specific task in mind, it is wise to consider a specialist tool for the job (i.e electrical pliers for wire cutting and crimping connectors) Electrical pliers provide a limited degree of protection to the user from an electric shock thanks to the use of insulation on the handles Lockwire pliers are used for the application of lockwire This material is used to secure nuts and bolts found on machinery subject to a great deal of vibration - the wire prevents them shaking loose It is commonly found on military vehicles and aircraft -6Copyright © Automotive Skills Limited 2003 All Rights Reserved LV02: Foundation Skills Issue Files and filing The file is a form of hand operated milling tool It can be used for shaping metal objects and dressing rough edges The body and heel are all cutting faces, whilst the tang is provided for the fitting of a handle All cutting portions are hardened and tempered, whereas the tang is usually left in a softened condition Using the file Flat triangle Round Flat Square Before using the file, ensure that the handle is secure by striking it lightly on a hard surface Apply the file to the work surface holding the handle with the master hand Guide the tool with the other Move the file tangentially to the work surface whilst applying light, even pressure The ability to file a surface flat will only develop with a great deal of practice! Work surface lines can be eliminated by rubbing chalk on the teeth of the file Regular use of chalk reduces the cutting depth and also reduces the likelihood of pinning (this is where swarf adheres to the file and scratches the work surface) It is also worth noting that a flat file is a rare thing indeed, you should also turn the file regularly during use -7Copyright © Automotive Skills Limited 2003 All Rights Reserved LV02: Foundation Skills Issue Hacksaw A technician’s role often requires the use of a hand cutting saw, such as a metal hacksaw It is commonly used to cut off rods, bolts and studs The replaceable blades are commonly made of alloy steel This gives excellent cutting properties but also provides a large amount of strength should the blade be accidentally twisted For most operations, a blade with 24 teeth per inch is ideal (this specification is still quoted in imperial measurement only) It is important when replacing a blade to ensure that the cutting teeth face forward This ensures that the removal of metal occurs on the forward (and most powerful) stroke An arrow on the blade is a fitting aid Whenever cutting material mounted in a vice, ensure that the orientation between the work piece, the vice and the saw is such that a slip cannot cause the vice or work piece to be ‘punched’ with the hand -8Copyright © Automotive Skills Limited 2003 All Rights Reserved LV02: Foundation Skills Issue Drills and drilling Drills are used to form holes in a variety of operations such as number-plate fitting, mud flap fitting and sheared bolt removal There are many different types of drill, but the most commonly used example is the twist drill The flutes formed by the twist of the drill aid swarf clearance Most good quality twist drills are made from high speed steel (HSS) and have excellent wear properties Drilling, as an operation in engineering terms, is an exact science However, as most drilling operations will be carried out by a technician using a hand drill (either pneumatic or electric), it should be noted that if an 8mm twist drill is used, the hole that results will often exceed this because of unavoidable movement during the drilling So, pick a small drill and work your way up! Always use a centre punch prior to drilling, to aid location of the twist drill centre - and to prevent ‘drift’ -9Copyright © Automotive Skills Limited 2003 All Rights Reserved LV02: Foundation Skills Issue European manufacturers Identify the symbols Write the name alongside each one - 50 Copyright © Automotive Skills Limited 2003 All Rights Reserved LV02: Foundation Skills Issue Locking and Securing Devices Bolts and screws Screw Bolt Coach bolt Countersunk screw Hex screw Self tapping There are many different types of locking device available, some of which are pictured here They are all designed with one primary task in mind – holding components together either permanently or temporarily A common misconception is that a screw has a sharp point and is designed to cut its own thread This is incorrect in engineering terms A screw is almost identical to a bolt with the exception that it is threaded all the way to the bottom of the head and is seldom used in conjunction with a nut (it screws into threaded components) A bolt has a thread ess shank Only self-tapping screws (cut their own thread) have sharp points! - 51 Copyright © Automotive Skills Limited 2003 All Rights Reserved LV02: Foundation Skills Issue Hexagon head bolts and screws are used far less frequently now than they were only a few years ago Multi-spline types and Torx types occur where a securing device needs to be accommodated in a tight space (with hexagon head devices, space needs to be left around the head to accommodate a socket for the fitting and removal) Tight spaces are now commonplace on light vehicles as manufacturers strive to save every gram of weight and exploit every centimetre of cabin space When ordering a bolt (standard design) from the parts department, expect to provide the following information if the device you want is not specific to task (such as a main bearing cap bolt): • overall length • diameter • thread pitch • strength rating A typical specification could be: 75mm long, M8 coarse thread, strength rating This is a bolt that is 75mm in length from its threaded end to the underneath of the head, has an mm thread diameter and a thread pitch of 1.5mm with a strength rating that would see it safe up to a torque of 60Nm - 52 Copyright © Automotive Skills Limited 2003 All Rights Reserved LV02: Foundation Skills Issue Nuts and washers Nut Castellated nut Nylock nut Flanged nut Wing nut Shear nut Nuts are also available in several different types When ordering, ensure the request is for a nut that has the same thread as the bolt to which it is to be fitted – this means both thread diameter and thread pitch Is it metric fine (1.25mm pitch) or metric coarse (1.5mm pitch)? The flanged nut is designed to spread the compression load a little onto the component surface The Nylock nut (trade name) is designed to grip the bolt thread by means of friction generated by the bolt’s thread It cuts through the nylon collar at the top of the nut It should be noted that these nuts should never be re-used Castellated nuts are designed for use in conjunction with split pins and wing nuts are used where regular and easy removal is required (seldom used on modern vehicles) Shear nuts are often the choice where security is an issue, with vehicle immobiliser equipment, for example Flat washer Penny washer Spring washer Washers are used to spread load and often to reduce the possibility of a bolt shaking loose as result of vibration Tab washers are made of a soft material (aluminium alloy) and are bent upward, to fit snugly against the flat of a screw head to prevent rotation and loosening of the screw through vibration - 53 Copyright © Automotive Skills Limited 2003 All Rights Reserved LV02: Foundation Skills Issue Chemical thread locking There are now many different types of chemical compounds available These can anything from locking a thread to prevent loosening as a result of vibration, to sealing joints and even temporarily sealing radiators, tyres or cylinder blocks! Always read the instructions thoroughly before use If unsure of the health and safety risks, always refer to the COSHH data sheet for that specific product - 54 Copyright © Automotive Skills Limited 2003 All Rights Reserved LV02: Foundation Skills Issue Progress check Answer the following questions: What type of nut is this? What is this locking device called? What is a tab washer for? When can a split pin be reused? - 55 Copyright © Automotive Skills Limited 2003 All Rights Reserved LV02: Foundation Skills Issue Inspection and Fault-Finding Techniques Diagnosis techniques Don’t rush in! Charging into a fault diagnosis procedure is seldom productive Working too quickly and without logical thought can lead to missing the simple, obvious faults that would have been identified through a more logical, structured approach With complex systems, a well-structured, logical approach is required This approach should be adhered to throughout diagnosis (simple or difficult) and in most cases the same approach can be used time and again Driver interrogation The driver of the vehicle probably knows more about the vehicle’s history than anyone else and will normally have first hand knowledge of the fault If a vehicle develops a fault, simple or complex, the driver will have sensed more of the symptoms than the technician can during workshop diagnosis It is important to ask drivers the right kind of questions The driver’s comments can prove valuable, especially with intermittent faults, which are often difficult to locate Asking the correct questions can produce answers that can usually save time by preventing unnecessary diagnostic routines Customers are normally willing to supply the information, so why not allow them to provide the information required to ease fault diagnosis? - 56 Copyright © Automotive Skills Limited 2003 All Rights Reserved LV02: Foundation Skills Issue Gathering information TPS MAP VOLTS ECM EARTH IDLE INJ IGN Build the puzzle until one of the pieces is missing or doesn't fit By gathering information about the problematic system, a logical diagnostic sequence can be determined to help identify the fault The area to be investigated can be reduced by carefully checking and testing strategic parts of the circuit Visual inspection It may seem that a large amount of data and information is required before fault diagnosis can begin, but by consulting a circuit diagram, certain sections of the circuit can be eliminated The large amount of information that seemed necessary at the start may not be required in the end Refer back to the information and the diagnostic sequence throughout the test routine It might be necessary to follow a different route if the components are too difficult to access or the findings are not as first thought Always be prepared to change or rethink the strategy Remember, charging into diagnosis is not always a good idea Sometimes it works, but more often than not what may be a simple procedure is made more difficult by missing the more obvious faults A more logical and structured approach will pay dividends - 57 Copyright © Automotive Skills Limited 2003 All Rights Reserved LV02: Foundation Skills Issue Formulating your diagnostic strategy Many technicians get lost in an attempt to diagnose complex electronic systems If there is insufficient information and the technician has a limited knowledge, guesswork has been known to take over Technicians often condemn a component that they not fully understand, or by looking at the quantity of the suspect component that the parts department sells This means that the parts person is diagnosing the fault! This is a potentially expensive (and embarrassing) strategy to adopt, as many parts departments will not allow the workshop to return parts once purchased If the new part ordered is not required (the guess was incorrect) the price of the part has to be absorbed by one of the parties - the workshop or customer When the price of the part is low (i.e £10.00), the amount can usually be absorbed as vehicle diagnostics time However, when the price of the part is high (i.e £200.00), it is a different story The customer will not absorb the cost The cost must be absorbed by the workshop, reducing profit If this happens on several occasions, confidence is lost and electrical/electronic diagnosis is then often contracted to other third party businesses - expensive! The reduction of such work in a workshop will quickly lead to de-skilling of the technical staff Technicians need to undergo regular training throughout their workshop life to allow them to service and repair modern motor vehicles When formulating a diagnostic strategy, prioritise Checking the obvious first When the electrical circuit being tested has an ECM, there is often a tendency to over complicate matters Many workshops not have equipment capable of testing complex electronic components (i.e ECM or similar) Therefore, they tend to think that the remainder of the circuit is also complex - 58 Copyright © Automotive Skills Limited 2003 All Rights Reserved LV02: Foundation Skills Issue There may be an electronic component at the centre of the circuit, but the remainder usually consists of general electrical items that can be tested with an ordinary multi-meter (bulbs, switches etc) It should be noted that although modern electrical circuits are often fitted with electronic control modules, the testing of such circuits still requires similar skills to those required when testing simple electrical circuits Getting bogged down thinking things are complex, can cause frustration if the fault isn’t initially obvious Record results as tests are carried out By recording the test results at each stage (correct or incorrect), the diagnostic plan can be reviewed at any time If for any reason diagnosis is interrupted, it is easier to return later and recall the results instantly A record of the test results will also assist if another person is asked to continue, without having to repeat the checks Diagnostic information is often difficult to access in the independent repair market and this type of information can be very valuable If information and data is collated every time a repair is carried out - whether it is information from repair manuals, information printed off test equipment or data gathered during test procedures – it can be used to construct an effective diagnostic library Few people are blessed with a photographic memory! It may take a little time to set up in the first instance, but over a short period the library will grow into a very large, in depth point of reference Some of the information obtained from test equipment data printout lists is not available from technical information suppliers and therefore a serviceable vehicle is a unique source of valuable data If the information is good or even bad (an idea is to highlight the bad data) the data can be used as a comparison against vehicles to be repaired in the future A simple PC is capable of providing an effective database utility at very little cost The information can then be catalogued into various categories and quickly referenced This approach is virtually guaranteed to increase productivity and profitability over time - 59 Copyright © Automotive Skills Limited 2003 All Rights Reserved LV02: Foundation Skills Issue Progress check Answer the following questions: Identify four different methods of diagnostic inspection (The first method has been given) A Visual B. ? C. ? D. ? What does ‘aural’ mean? What does the term guarantee refer to? - 60 Copyright © Automotive Skills Limited 2003 All Rights Reserved LV02: Foundation Skills Issue ... Progress check 6 7 10 10 11 11 12 13 Measurement: Length Area Volume Exercise 14 14 15 16 17 Pressure: What is pressure? 18 18 Page … Pressure units Pressure in liquids Progress check 20 21 22 Measuring... radius of 10 cm, the surface area of one end will be: 3 .14 2 x 10 x 10 = 314 .2cm² If it is now assumed that its length is 10 cm, the volume of the cylinder will be: 314 .2cm² x 10 = 314 2cm³ - 16 Copyright... Pascal 10 00 N/m² is therefore kPa (kilo Pascal or 10 ,000 Pascals) 1, 000,000 N/m² is therefore 1MPa (Mega Pascal or 1, 000,0000 Pascals) 0 .1 MPa is Bar (10 0 kPa) Bar is 15 p.s.i 15 p.s.i is 10 0 kPa