NATIONAL CERTIFICATE (VOCATIONAL) AUTOMOTIVE REPAIR AND MAINTENANCE NQF LEVEL 4 NOVEMBER 2009

Transcription

1 NATIONAL CERTIFICATE (VOCATIONAL) AUTOMOTIVE REPAIR AND MAINTENANCE NQF LEVEL 4 NOVEMBER 2009 ( ) 12 November (Y-Paper) 13:00 16:00 This question paper consists of 8 pages.

2 ( ) -2- NC260(E)(N12)V TIME: 3 HOURS MARKS: 150 INSTRUCTIONS AND INFORMATION Answer ALL the questions. Read ALL the questions carefully. Number the answers according to the numbering system used in this question paper. Write neatly and legibly.

3 ( ) -3- NC260(E)(N12)V QUESTION 1: TEST, DIAGNOSE AND RECTIFY FAULTS IN AN ELECTRONIC FUEL INJECTION SYSTEM ON AN ENGINE 1.1 Describe the difference between operating pressure and retention pressure in an electronic fuel injection system. (4) 1.2 State FIVE safety precautions you should consider when working on an EFI system. (5) 1.3 Self-test codes are the result that you get if you do a test with diagnostic tools. These tools display different codes that tell you which parts of the vehicle are faulty. In industry the types of codes used are called on board diagnostics (OBD). This means that the system reads information from the vehicle. P0123 is an example of an OBD-11 CODE. Each of the letters or numbers stands for something. Give the meaning of each of the following codes: B; C; P. (3) 1.4 Draw up a simple recording sheet in the ANSWER BOOK and record TWO test results/faults as well as a possible remedy for the fault. (4) 1.5 Explain a simple test that could indicate an unserviceable injector and state ONE possible cause for why the injector is unserviceable. (2 + 2) (4) [20] QUESTION 2: DIAGNOSE AND REPAIR FAULTS IN INDUCTION AND EXHAUST SYSTEMS 2.1 Explain the function of the fuel pump. (2) 2.2 What is the meaning of the following acronyms: ECM ECI EFI ECU 2.3 State THREE basic checks that you would conduct on the fuel supply system. (6) 2.4 Describe how you would carry out a cylinder contribution test (cylinder balance test). Include the relevant electronic diagnostic tool you would use during this test. (3) 2.5 Explain the simple test that you would perform to determine if the lift pump is in good working order. (2) [17]

4 ( ) -4- NC260(E)(N12)V QUESTION 3: DIAGNOSE AND REPAIR HYDRAULIC BRAKE SYSTEMS 3.1 Indicate whether the following statements are TRUE or FALSE. Choose the answer and write only 'true' or 'false' next to the question number ( ) in the ANSWER BOOK Potential energy is the energy of motion. Kinetic energy is the amount of energy in a body at rest. Heat energy is transferred by heat. Boiling point for brake fluid is 100 degrees Celsius. 3.2 State FOUR properties of a good brake fluid. (4) 3.3 Name TWO forces that will increase your stopping distance. (2) 3.4 Explain the principle of thermodynamics. (2) 3.5 Explain the operation of the S-cam during brake application. (2) [14] QUESTION 4: DIAGNOSE AND REPAIR COOLING SYSTEMS 4.1 Name any TWO types of cooling systems. (2) 4.2 Explain the function and operation of the water pump. (2) 4.3 A customer brings a vehicle to you. He/She complains that the engine coolant level drops regularly. Explain how you would go about tracing the water leak by using the applicable testing equipment. (4 x 1) (4) 4.4 What steps would you follow to inspect, replace and adjust a fan belt? (4 x 1) (4) 4.5 Name two important characteristics of a good coolant. (2) [14]

5 ( ) -5- NC260(E)(N12)V QUESTION 5: REPAIR MANUAL TRANSMISSIONS 5.1 DIAGRAM 1 below shows a sectional view of a diaphragm spring type clutch assembly. Name the parts numbered to (6) DIAGRAM Describe the operation of the drive shaft and universal components. (2) 5.3 Explain the power flow from the crankshaft to the input shaft in a manual transmission. (2) [10]

6 ( ) -6- NC260(E)(N12)V QUESTION 6: REPAIR SUSPENSION SYSTEMS 6.1 Explain the difference between body sway and ride height. (2) 6.2 State any SIX pre-alignment checks to be done before wheel alignment can be carried out. (6) 6.3 Describe the following terms: Toe-out on turns (2) Negative caster (2) 6.4 What is the function of a McPherson strut? (2) 6.5 What are the root causes for the following unusual tyre wear patterns: Tyre is worn in the centre of the tread Tyre is worn on both sides Tyre is worn only one side [17] QUESTION 7: DIAGNOSE AND REPAIR STEERING SYSTEM COMPONENTS 7.1 What relevant information is required for emergency procedures to be carried out on a steering system? (4 x 1) (4) 7.2 Explain how to align the steering wheel. (3 x 1) (3) 7.3 State FOUR root causes for steering vibration. (4) [11] QUESTION 8: SERVICE AND REPAIR AUTOMOBILE ELECTRONIC IGNITION SYSTEMS 8.1 Explain the basic operating principles of the refrigeration cycle of the airconditioning components of an automobile air-conditioning system. (2) 8.2 State the function of a diode and a transistor as used in an electronic ignition system. (2) 8.3 Discuss the fundamentals of advanced electronics. (2)

7 ( ) -7- NC260(E)(N12)V 8.4 Name TWO components used in an automobile electronic ignition system. (2) 8.5 What are TWO safety practices that you must apply when fitting and wiring auxiliary auto-electrical equipment? (2) [10] QUESTION 9: REPAIR VEHICLE DIFFERENTIALS 9.1 DIAGRAM 2 below shows a common type of differential as used on rear wheel drive vehicles. Write the names of the parts next to the question numbers ( ) in the ANSWER BOOK. (4) DIAGRAM What is the difference between total pre-load and pinion pre-load? (4) 9.3 Explain how to perform tooth contact pattern. (4) 9.4 What is the measuring instrument that is most commonly used to measure backlash between the crown wheel and the pinion on a differential? [13]

8 ( ) -8- NC260(E)(N12)V QUESTION 10: RECONDITION A VEHICLE SUB-ASSEMBLY 10.1 Differentiate between ferrous and non-ferrous metals. (2) Name the part in the sub-assembly that rotates most. Explain how to measure end float on a crankshaft. (2) 10.4 Why is it important to arrange engine parts in a proper sequence after dismantling? 10.5 Explain the difference between taper and ovality in a cylinder bore. (2) 10.6 Why is it important to dispose of waste material according to the Safety Health Environment (SHE) Act? 10.7 Explain the principles of lubricants related to internal combustion engines. (2) [11] QUESTION 11: TEST AUTOMATIC TRANSMISSION 11.1 Choose a function from COLUMN B that matches the name of the part in COLUMN A. Write only the letter (A D) next to the question number ( ) in the ANSWER BOOK. COLUMN A COLUMN B Neutral gear First gear Second gear A B both rear clutch and overrunning clutch are engaged both the front clutch and rear band are applied Reverse gear C the front band is applied and the rear clutch is engaged D clutches and bands are not engaged (4) 11.2 Describe the function of the torque converter. (3) 11.3 State the SIX steps you would follow to check the level of the transmission fluid. (6) [13] TOTAL: 150