Learner workbook

Activity 2

Accurate diagnosis is important because:

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  It can save the customer money
  
• 
  It can reduce workshop costs
  
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  It keeps customers happy with your work
  
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  It reduces the chance of having to do the job again.
  
  

When diagnosis is quick, efficient and accurate:

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  Workshop productivity is improved
  
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  The technician’s skills are demonstrated and valued
  
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  The workshop can close early for the day
  
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  The customer gets his/her vehicle back in reasonable time at affordable cost.
  
  

A symptom is:

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  A piece of equipment
  
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  Someone who has knowledge
  
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  A noticeable change
  
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  No change in operation.
  
  

Symptoms can be recognised because they:

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  Make vehicles perform normally
  
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  Change how something performs
  
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  Are imagined by the owner
  
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  Are a noticeable change in performance.
  
  

A symptom is:

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  A sign that something is operating
  
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  An unnoticeable change in a vehicle’s operation
  
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  The failure of some component or system
  
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  A perceptible change in a vehicle’s operation.
  
  

A fault is a component or system which is:

• 
  Not working at all
  
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  Not there at all
  
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  Not doing what it is supposed to be doing
  
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  Worn, broken or out of adjustment.
  
  

A cause is:

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  When the vehicle fails completely
  
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  When only part of a system is working
  
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  The reason why a fault occurs
  
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  An abnormal state in a component or system.
  

Here are three statements about a vehicle with a problem.

Which is the symptom, fault, and cause?

Draw lines to match each statement with the correct box.

Describe a simple problem that you have come across at work recently.

Write down the symptom, fault and cause of the problem. You may also explain your answer to your teacher.

SYMPTOM
FAULT
CAUSE

Trainer Signature: .............................................................. Date: .....................

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Diagnosing is not guessing

If you want to find the cause which led to the fault and the symptom, you need to:

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  Gather more information about the complaint
  
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  Gather more information about the systems involved
  
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  Carry out a variety of tests
  
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  Think about (analyse) your information and test results; and
  
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  Confirm the cause of the problem.
  
  

The steps in a diagnostic procedure

The diagnostic procedure you should use in the auto repair industry is similar to what a doctor does when you walk into the surgery with a minor illness.

Diagnostic step	What the doctor does
Gather more information about the problem	Asks what your symptoms are (cough/cold/dizziness/pain in the leg/head ...)
Gather more information about the systems involved	Asks questions -how long have you had the cough/cold? What sort of cough is it? Can you show me? Where is the pain? How bad is it? Checks your past medical history in her records.
Carry out a variety of tests using test equipment	Uses a stethoscope to listen to the cough, measures blood pressure or temperature, probes or manipulates the painful area, x-ray etc Might also consult some other source of medical information eg books, internet, colleagues
Think about (analyse) the information and test results and reach a diagnosis	Considers all the information gathered, including test results Compares this with her expert medical knowledge of the human body Works out the cause of your problem
Decide on the “repair”	Prescribes the treatment for your condition eg medication/physiotherapy/brain transplant etc
Confirm the cause of the problem.	Asks you to come back for a check-up to make sure the problem is fixed

Your doctor follows a logical diagnostic procedure. She is able to treat you successfully because:

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  She has a very good understanding of the system in which the problem exists.
  
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  She applies a logical, systematic procedure to working out what the cause of the problem was.
  
  

You need to be able to do exactly the same to successfully diagnose vehicle faults!

Gathering information for diagnosis

Following a procedure (a set of steps) is nothing new to automotive repair technicians. When you change a wheel on a vehicle you follow a procedure to make sure it is changed safely and refitted securely.

This procedure might be developed by the vehicle manufacturer or you can create your own procedures to follow. Sometimes you might combine these for a particular job.

Your knowledge

Your diagnostic ability depends on a good knowledge and understanding of the system in which the problem exists. But you can’t know everything! Most technicians become very familiar with particular systems (engine management, for example) on a limited range of vehicles.

When you find that you don’t know enough about a vehicle system, where can you look for help?

Use other sources of information

Gathering information is part of the diagnosis process and is often easily available.
Some of the reliable sources you could use are:

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  Other technicians in the workshop
  
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  Workshop manuals, and manufacturer’s technical hot-lines
  
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  Service bulletins from the manufacturer
  
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  Service information from industry and commercial associations e.g. AACC, IAME, Autotech.
  
  

Keep up-to-date
Internet Information-
Never believe information you find on the Internet unless you are absolutely certain that it comes from either an official factory site, or is otherwise totally reliable.

Never trust anything you read on sites such as the one-make forums- they are usually full of misinformation and myths.

As a professional, you should take every opportunity to improve your knowledge.
Don’t leave it until you’re in the middle of a diagnosis job!

Keep your knowledge up to date through:

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  Workplace training
  
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  TAFE courses
  
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  trade association courses
  
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  technical journals (publications)
  
• 
  workshop manuals.
  

Types of diagnostic procedures

There are lots of different procedures for diagnosis of vehicle faults, but they are all logical and systematic. This workbook will deal with:

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  Step-by-step procedures
  
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  Branching procedures
  
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  ‘Black box’ procedures.
  

Often a diagnostic procedure can be shown on a diagram. In the medical example described earlier, the doctor followed this step-by-step process:



Figure 4: Step-by-step procedure

This could be used as a general procedure to follow on other diagnosis tasks.

Often you can make a few small adjustments to suit the particular job.

Feedback Loops

Here is another, slightly different, diagnostic chart. It has a “feedback loop” which prompts you to re-test or do further tests if you don’t find the fault on the first attempt.



Figure 5: Feedback loop

You can see that both of these diagnostic procedure flow charts are quite similar.

You could apply these procedures to many straightforward diagnosis jobs.


An easy diagnosis

A customer traded in his old car on a new one. A month or two later he returned to the dealership complaining that recently, when he had to make an emergency stop, there was “a groaning noise and the brake pedal felt funny”.

When he demonstrated this to the technician it was clear that he had simply felt the normal operation of the anti-lock braking system in his new car which he had never experienced before. He was very pleased to be told that there was no problem, and to be given instructions on the correct way to use ABS in an emergency.

However, most diagnosis isn’t that simple.

However,

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Activity 3

Tick the correct answer/s. There may be more than one correct answer.

Question 1

Which of these things are essential steps in any diagnostic procedure?

• 
  Carrying out tests
  
• 
  Analysing information
  
• 
  Substituting parts
  
• 
  Gathering information.
  
  

Question 2

Write the 6 actions on the left into the boxes.

Put them in the best order to show a simple diagnostic procedure.

Consider the information Repair the fault Carry out more tests if needed Verify that the fault exists Check the fault is fixed Gather information	1.
	2.
	3.
	4.
	5.
	6.

Question 3

When diagnosing vehicle faults, it is important to keep up with the latest information. What are some ways you could increase your knowledge of the systems you work on?

List them below.

Question 4

A ‘feedback loop’ in a diagnostic procedure can:

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  Cause an abnormal noise in the audio system
  
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  Take you out of the procedure and direct you to another job
  
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  Prompt you to re-test, or make extra tests
  
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  Give advice on how to arrange the wiring loom.
  

Ask your trainer to check your results before proceeding.

Trainer Signature: .............................................................. Date: ....................

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