Vehicle Electrical And Electronic Diagnosis 2

1. Which of the following are benefits of a circuit breaker over a traditional fuse?

More expensive to produce but can be reset manually

Easier to replace than a traditional fuse

Amp rating can be adjusted to add additional circuits

Quick reaction time and greater reliability

A circuit breaker is often used with electronic circuits as they are faster acting to high current surges to protect the circuit and this makes the reliability of breaking the circuit at an accurate level greater

Explanation

A circuit breaker is often used with electronic circuits as they are faster acting to high current surges to protect the circuit and this makes the reliability of breaking the circuit at an accurate level greater

2. If an open circuit within the earth circuit was identified on an electric window what would be the most likely outcome

The window would not go down

The window would not operate at all

The window would go down but not go back up

The window would operate normally as it has a switched earth

As the window operates on a switched earth or swiched power system an open circuit on either side of the motor would leave it inoperable.

Explanation

As the window operates on a switched earth or swiched power system an open circuit on either side of the motor would leave it inoperable.

3. When testing an electric window fault it appears that battery voltage is being recieved at both sides of the motor, is this correct or incorrect?

Incorrect as the motor would burn out

Correct, as one of the voltages will change when operated

Correct as both of the voltages would drop to zero when operated

Incorrect, as the motor requires a difference in voltages to operate

The motors used are generally reversible motors which would be either battery voltage at both brushes or earthed at both brushes when at rest. When operated with this example one brush would be linked to earth to create a potential difference and thus rotary motion, the earth path would be switched to the other brush to reverse the motion. These are often referred to as switched earth systems

Explanation

The motors used are generally reversible motors which would be either battery voltage at both brushes or earthed at both brushes when at rest. When operated with this example one brush would be linked to earth to create a potential difference and thus rotary motion, the earth path would be switched to the other brush to reverse the motion. These are often referred to as switched earth systems

4. If an air conditioning system is controlled by an ECU to gain optimum temperature control within the cabin this is often referred to as....

Climate Control System

Cimate Adjustment System

Automatic Air Conditioning System

Air Conditioning

A standard air conditioning system would have manual controls within the cabin similar to traditional heater controls. A climate control system would often be digital tempwerature settings which can automatically adjust fan speeds to keep cabin temperature at a set level. More modern systems also give extra features like different settings for front and rear or even passenger and driver.

Explanation

A standard air conditioning system would have manual controls within the cabin similar to traditional heater controls. A climate control system would often be digital tempwerature settings which can automatically adjust fan speeds to keep cabin temperature at a set level. More modern systems also give extra features like different settings for front and rear or even passenger and driver.

5. A customer complains that their heater fan only works on the high speed setting what is the most common fault?

Motor Brush Failure

Resistor Pack Fault

Broken Switch

Fuse Blown

The heater fan often used a resistor pack to achieve the slower fan speeds, resistors in series split the voltage and hence a reduced fan speed. As the resistors are in series one damaged resistor would break the circuit resulting in all slower speeds being inoperative. The high speed setting generally would not run through the resistor pack so a damaged resistor pack would not effect the high speed setting.

Explanation

The heater fan often used a resistor pack to achieve the slower fan speeds, resistors in series split the voltage and hence a reduced fan speed. As the resistors are in series one damaged resistor would break the circuit resulting in all slower speeds being inoperative. The high speed setting generally would not run through the resistor pack so a damaged resistor pack would not effect the high speed setting.

6. When related to multiplexed systems which is the most accurate statement?

A traditionally wired electrical systems seding and recieving signals to remote control units

A traditionally wired electrical system incorporating electronic components

A data bus system recieving signals from remote control units

A data bus system carrying signals to and from remote control units

A modern vehicle will often include multiplex wired systems which are often referred to as Can Bus systems. These systems link various ECU's and remote nodes to communicate with each other.

Explanation

A modern vehicle will often include multiplex wired systems which are often referred to as Can Bus systems. These systems link various ECU's and remote nodes to communicate with each other.

7. If a leak in an air conditioning system was present what would you expect to happen?

The TXV Valve would prevent refrigerant flow

The system would operate normally unit the gas had been exhausted

The compessor would have its drive disconnected due to low level refrigerant

The system would regulate the refrigerant flow for optimum performance

A leak would be detected by the system as it has a built in pressure sensor if the pressure level drops below a pre set level it would cut the power to the elctromagnetic clutch system which drives the compressor. This would stop the flow of refrigerant and highlight a problem to the driver of a refrigerant leak

Explanation

A leak would be detected by the system as it has a built in pressure sensor if the pressure level drops below a pre set level it would cut the power to the elctromagnetic clutch system which drives the compressor. This would stop the flow of refrigerant and highlight a problem to the driver of a refrigerant leak

8. If a GPS unit fails to locate a vehicle posistion what is the most likely fault?

The system has not located the satelittes yet and would continue to send and recieve signals until an exact location is achieved.

The system needs a minimum of four satelittes in view to operate

The system needs an input from various sensors on the vehicle to pin point location

Only two satellites are in view of the reciever

A Global Positioning System requires a signal from three satelites to triangulate the position of the vehicle this accurate position is then transposed onto a digital map.

Explanation

A Global Positioning System requires a signal from three satelites to triangulate the position of the vehicle this accurate position is then transposed onto a digital map.

9. What two components would you expect to find within a door lock actuator?

Motor and gear

Solenoid and gear

Motor and solenoid

Relay and Motor

Most traditional systems would incorporate a DC Motor operating a rack and pinion type gear set, The plastic gear set would convert the reversing rotary motion of the motor into linear motion requied to operate lock rods within the door.

Explanation

Most traditional systems would incorporate a DC Motor operating a rack and pinion type gear set, The plastic gear set would convert the reversing rotary motion of the motor into linear motion requied to operate lock rods within the door.

10. What is the term used when a DC motor uses the electrical charge held within the armature to prevent the effects of inertia when power is removed?

Regenerative braking

Regenerative rotation

Rotational braking

Electromagnetic braking

Regenerative braking is a term used to prevent a motor from rotating by earthing both brushes of a single speed motor.

Explanation

Regenerative braking is a term used to prevent a motor from rotating by earthing both brushes of a single speed motor.