Unit 74 Vehicle Fault Diagnosis


Unit 74:

Vehicle Fault Diagnosis


Unit code:
H/601/1375

QCF level:
4


Credit value:
15






Aim

This unit will develop learners’ understanding of vehicle fault diagnosis and will give them the practical skills needed to diagnose vehicle faults and assess serviceability.

Unit abstract

This unit will provide learners with an advanced understanding of vehicle fault diagnosis and will enhance their ability to diagnose faults and select appropriate equipment from given data in a number of disciplines. They will also learn about techniques of measurement when determining the performance of a vehicle system.

Learning outcome 1 will enable learners to increase their knowledge of fault diagnostic techniques and the interpretation of fault symptoms. Learning outcome 2 considers the principles of measurement and testing to determine the performance of vehicle systems. Learning outcome 3 is concerned with the evaluation and presentation of test results and the production of a fault location guide for a given vehicle.

Learning outcomes

On successful completion of this unit a learner will:

1       Understand vehicle systems fault diagnosis criteria and techniques

2       Be able to use fault diagnostic techniques and equipment to determine the performance of vehicle systems

3       Be able to evaluate and present findings of a vehicle fault diagnostic test and produce a fault location guide.
Unit content

1      Understand vehicle systems fault diagnosis criteria and techniques

Diagnosis specifications: prioritised list of technical and non-technical requirements for carrying out fault diagnosis; symptoms; repair recommendations eg for mechanical, electrical, electronic or computer-based vehicle systems

Diagnostic techniques: eg symptom-fault-cause-location diagnostic sequence, historical knowledge of system faults, application of problem solving techniques

Factors: factors that contribute to diagnosis eg logical process, diagnostic and specialist equipment required, on-board computer-based and telemetry diagnostic systems, equipment costs, likely time saving, ability to upgrade, ease of use, manufacturers’ back-up, workshop manuals, technical (phone/fax/email/internet, technical bulletins)


2      Be able to use fault diagnostic techniques and equipment to determine the performance of vehicle systems

Test equipment: equipment eg cylinder leakage tester, exhaust gas analyser, electronic meter, fuel pressure gauge, engine analyser, computer based and telemetric devices Fault diagnosis: diagnosis on the agreed vehicle systems; diagnostic aids

Symptoms: fault symptoms eg loss of power, high fuel consumption, poor acceleration

Repair recommendations: type of repair eg adjustment, replacement, repair; justification of solution(s) eg based on cost, serviceability, reliability, safety

3      Be able to evaluate and present findings of a vehicle fault diagnostic test and produce a fault location guide

Technical report: word-processed technical report including nature and setting of the fault eg vehicle, symptoms, setting (road side or workshop), suspected system or systems, description of techniques and equipment used, test results, interpretation of results, conclusions and known data for that system, references used

Present findings: presentation eg to peers and/or supervisor/tutor; use of suitable visual aids eg sketches, graphs, charts, drawings, spreadsheets; use of presentation packages where appropriate

Fault location guide: prepared for a given vehicle system and including expected test readings, description of the system with an explanation of its use, theory of operation, instruments and special tools required, test instructions, step-by-step fault location guide to fault diagnostic procedure

Learning outcomes and assessment criteria


Learning outcomes

Assessment criteria for pass



On successful completion of

The learner can:



this unit a learner will:














LO1 Understand vehicle systems

1.1
identify and justify a diagnosis specification for a


fault diagnosis criteria and



mechanical or an electrical or an electronic vehicle


techniques



system




1.2
use, explain and record the results of at least two






suitable vehicle systems diagnostic techniques




1.3
compare the factors that contribute to quick and






effective diagnosis of a given vehicle system








LO2 Be able to use fault

2.1
select and use appropriate test equipment



diagnostic techniques and

2.2
carry out a systematic fault diagnosis



equipment to determine the










performance of vehicle

2.3
interpret faults from given symptoms and justify repair



systems


recommendations











LO3 Be able to evaluate and

3.1
produce a written report of the test results


present findings of a vehicle

3.2
interpret and justify the test results in terms of the


fault diagnostic test and






known data for that system


produce a fault location












guide

3.3
create an effective fault location guide for a mechanical






or an electrical or an electronic system.










Guidance
Links

This unit has links with Unit 25: Engine and Vehicle Design and Performance, Unit 75: Vehicle Systems and Technology and Unit 79: Vehicle Electronics.

Essential requirements

A number of suitable diagnostic aids are essential for the delivery of this unit including a compression tester, cylinder leakage tester, engine analyser and multimeters. Access to manufacturers’ manuals and vehicle data is also required.

Employer engagement and vocational contexts

Delivery of this unit would benefit from guest speakers from industry and visits to motor industry test facilities.



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