4290-153 Revision Pt3

4290-153 Revision Pt3

by Teach Teach

Multiple Choice

Name the component shown in the image:

• Alternator

• Starter.

• Compressor.

• Fuel pump.

​The component is an alternator; it is usually driven by a belt from the crankshaft.

Multiple Choice

What is the correct name of the symbol shown?

• Fuse.

• Light Emitting Diode.

• Two way Switch.

• Diode.

​The diode is a form of one-way electronic switch. Electric current can only pass in one direction, electricity will only flow from anode to cathode.

​Anode (+)

​Cathode (-)

Multiple Choice

Which one of the following protects the circuits from overload?

• Multi-plug.

• Push switch.

• Circuit breaker.

• Relay.

​The circuit breaker is sensitive to current flow. When it becomes excessive, it causes

an automatic break in the circuit, so preventing damage and possible fire.

Multiple Choice

What does NTC stand for on a temperature sensor?

• Negative thermal coefficient.

• Normal thermal coefficient.

• Negative temperature coefficient.

• Negative thermistor coefficient.

​With a negative temperature coefficient sensor, its resistance decreases as its temperature increases.

Multiple Choice

Which type of starter is shown in the diagram?

• Inertia.

• Pre-engaged.

• Full flow.

• Recoil.

​With the pre-engaged starter, the pinion is moved into mesh by a solenoid fixed to the starter.

Multiple Choice

Which one of the following gases is released when charging a battery?

• Hydrochloride.

• Sulphuric.

• Hydrogen.

• Carbon dioxide.

​Hydrogen gas is formed during charging and discharging. This presents a risk of an explosion, so great care must be taken when handling batteries.

Multiple Choice

On starting a car, there appears to be a loud squealing noise from the engine

area. Which one of the following is a possible fault?

• Flat battery.

• Loose rocker arm.

• Bad earth.

• Under-tensioned drive belt.

​An under-tensioned drive belt will slip on the drive pulleys. It is particularly noticeable just after starting a car as the alternator will be producing a high output.

Multiple Choice

Which one of the following is the component shown in the image?

• Window switch.

• Sunroof motor.

• Wiper motor.

• GPS antenna.

​The component shown is positioned under the bonnet and is a wiper motor.

Multiple Choice

Which one of the following must be observed when removing electrical

components?

• Easiest way to remove them.

• Quickest way to remove them.

• The manufacturer’s instructions.

• The vehicle’s service book.

​Most electrical systems and components are very sensitive and can be damaged by voltage surges. It is very important to observe the correct procedure when disconnecting electrical components.

Multiple Choice

A common fault which causes the interior fan not to work at different speeds is

often caused by:

• leaves stuck on the fan.

• blocked pollen filters.

• faults in the multi-resistor block.

• fan motor totally burnt out.

​A faulty multi-resistor block will affect the operation at different speeds. The resistors are wired in series, they reduce flow to motor slowing it's operation, if one fails then they all fail. This would mean that only full speed - where the resistors are by-passed - would operate.

Multiple Choice

How are dedicated fault code readers connected to the vehicle?

• CAN-BUS connector.

• Sensor wire.

• Serial link.

• Auxiliary socket.

​Dedicated fault code readers connect to the vehicle through the EOBD (European On Board Diagnostic) serial port connector. This is also known as the DLC (Data Link Connector).

Multiple Choice

When carrying out the test shown, the multimeter is set to 12V and the component is operating. Which one of the following tests is being carried out?

• Supply voltage at the relay.

• Supply voltage at the motor.

• Earth connection of the relay.

• Voltage drop across the relay.

​When a voltmeter is connected as shown, it will indicate any loss, or drop of voltage, between the two connecting points. This is the most efficient way to test a relay's operation.

Multiple Choice

When using an ohmmeter to measure the resistance of a component fitted

into a circuit, the circuit must be

• earthed

• disconnected

• switched on

• connected to an auxiliary supply.

​An ohmmeter measures resistance by passing a very low voltage through the circuit or component. It is therefore important that the main circuit is disconnected.

Multiple Choice

What is represented by the electrical symbol shown?

• fixed resistor

• light emitting diode

• variable resistor

• capacitor

​The symbol shown is a variable resistor; the other components have different symbols.

​Fixed resistor

​

​

​

​Light emitting Diode

​

​

​Capacitor

Multiple Choice

When set at position 3 the meter shown is used to measure

• ac voltage

• dc voltage

• resistance

• battery voltage

​The symbol shown at 3 is the unit symbol for ohms, the unit used for measuring resistance.

Multiple Choice

What is the power consumed by a solenoid when the voltage supplied is 15 volts

and the current flow is 5 amps?

• 3 watts.

• 5 watts.

• 75 watts.

• 15 watts.

​The calculation for Power (Watts) is Voltage x Current (amps). So 15 x 5 = 75 Watts.

Multiple Choice

If the third brush in a wiper motor is faulty it would affect the

• two-speed operation

• wash wipe function

• self parking

• intermittent operation

​The third brush is used to provide the fast speed; if there was a problem it would affect the two speed operation. The third brush being closer to the earth allows full current through less coils, so making motor spin faster as there will be less resistance.

Multiple Choice

When removing an air bag from a vehicle it is necessary to wait several minutes

after disconnecting the battery to allow the

• static electricity to drain

• capacitors to discharge

• impact sensors to switch off

• deceleration sensors to switch off

​Capacitors contain their ‘charge’ for some time after disconnection; it is important to wait several minutes to ensure the unit is safe to handle.

​It may also help to turn on unit after disconnecting the battery.

Multiple Choice

Which one of the following can be used to test a diode?

• Stall tester

• Continuity tester

• Ammeter

• Scanner

​A diode allows current to flow in one direction, when checking the continuity flow should be in one direction only.

Multiple Choice

The diagram shows an oscilloscope pattern for which one of the following

signals?

• CAN bus.

• Sine wave.

• Stepper motor.

• Analogue voltage.

​The signal shown is a CAN bus signal; the other options will produce a signal pattern but will be different to the one shown.

​Sine wave is also the signal wave that an AC voltage produces.

​Stepper motor wave signal on an Oscilloscope.

​End of test