sample answer ae06

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Sample Answer AE06

Assignment:

Electric Window & Supplementary Restraint and Airbag

1. Provide a detailed description of the construction and operation. 10 marks AC (1.1, 1.2, 1.3, 3.2)

1.1 Explain the principles of electrical inputs, outputs. Voltages and oscilloscope patterns, digital

and fibre optics

1.2 Explain the principles of sensor inputs, computer processing and actuator outputs

1.3 Identify sensor types (passive and active)

3.2 Explain the construction and operation of automotive auxiliary electrical systems

(a) Electric Window

Construction:

The window lift on most cars uses a really neat linkage to lift the window glass while keeping it level.

A small electric motor is attached to a worm gear and several other spur gears to create a large gear

reduction, giving it enough torque to lift the window.

The linkage has a long arm, which attaches to a bar that holds the bottom of the window. The end of

the arm can slide in a groove in the bar as the window rises. On the other end of the bar is a large

plate that has gear teeth cut into it, and the motor turns a gear that engages these teeth.

The same linkage is often used on cars with manual windows, but instead of a motor turning the

gear, the crank handle turns it.

Wiring circuit and switches:

Car doors are wired in many different ways, depending on which features are incorporated. We'll go

through the wiring on a basic system -- one that allows the driver to control all four windows on the

car and can lockout the controls on the other three individual windows.

Lift up Lift down

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Simple power window system:

On this system, the power is fed to the driver's door through a 20-amp circuit breaker. The power

comes into the window-switch control panel on the door and is distributed to a contact in the center

of each of the four window switches. Two contacts, one on either side of the power contact, are

connected to the vehicle ground and to the motor. The power also runs through the lockout switch

to a similar window switch on each of the other doors.

When the driver presses one of the switches, one of the two side contacts is disconnected from the

ground and connected to the center power contact, while the other one remains grounded. This

provides power to the window motor. If the switch is pressed the other way, then power runs

through the motor in the opposite direction.

Advanced power window system:

On some cars, the power windows work in a completely different way. Instead of the power for the

motor going through the switches directly, the switches are connected to one of the many

electronic modules in the car (the average car contains 25). Some cars have one in the driver's door,

as well as a central module called the body controller.

Cars that have lots of controls on the door are more likely to have a setup like this. Some cars have

the power-window, power-mirror, power-lock and even power-seat controls all on the door. This

would be too many wires to try to run out of the door.

Instead of trying to do that, the driver's door module monitors all of the switches. For instance, if

the driver presses his window switch, the door module closes a relay that provides power to the

window motor. If the driver presses the switch to adjust the passenger-side mirror, the driver's door

module sends a packet of data onto the communication bus of the car. This packet tells the body

controller to energize one of the power-mirror motors.

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2. Analyze two different typical electrical faults - one for each of the systems chosen. Explain the

symptoms and causes of the faults.(10 marks) AC (1.1, 1.2, 1.3, 3.2)

1.1 Explain the principles of electrical inputs, outputs. Voltages and oscilloscope patterns,

digital and fibre optics

1.2 Explain the principles of sensor inputs, computer processing and actuator outputs

1.3 Identify sensor types (passive and active)

3.2 Explain the construction and operation of automotive auxiliary electrical systems

Electric Window

No power supply

When a power window fails to operate, a short checklist helps to narrow the possible

causes. If all windows stopped working at once, a loss of power to the system is

likely. Most systems use a single relay and power supply for all windows. When all

windows quit working simultaneously, first check for a blown fuse or bad relay.

Certain power window switch not function

When a certain power window fails to operate, a possibly cause happen to the

particular switch or wiring harness. It may loose connection on harness or damage

switch.

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3. Explain the systematic diagnostic techniques used to identify the faults. Include the complete

process; from initial inspection through to confirmation of the faults.(10 marks) AC (5.1, 5.3)

5.1 Explain the symptoms and causes of faults found in automotive auxiliary electrical systems

5.3 Explain how to examine, measure and make suitable adjustments to components

Electric power window

Symptoms – Electric power window malfunction

(all unit not operating or single unit not

operating)

Possible cause will be, if all unit not operating.

open circuit in main supply, main fuse blown,

relay coil or contacts open circuit or high

resistance.

Possible cause will be, if one unit not operating.

fuse blown, control switch open circuit, motor

seized or open circuit, back-off safety circuit

signal incorrect (windows)

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4. Explain the type of diagnostic measurements and readings expected to be found during the

process, and how these readings would compare to the manufacturer’s specifications.

(10 marks) AC (5.6)

5.6 explain how to evaluate and interpret test results found in diagnosing automotive auxiliary

electrical system faults against vehicle manufacturer specifications and settings.

Electrical Window:

Voltage drop testing

Finding current at the motor, below system voltage, suggests high resistance in the

circuit. Voltage drop testing is handy for finding the source. For example, voltage at

the motor side of the connector may read 11 volts, with the switch turned to on. If

system voltage is 12 volts, we have resistance in the circuit. This may cause the

motor to run slowly or not at all. High resistance can also cause repeat motor failures.

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Testing Analog power window switches

Switch at rest

When we are not using the power window switch, it is in the rest state. This means

that no current will flow to the motor on either wire. If we check the connector at the

motor, neither lead shows current when we check to ground. Both leads may show

continuity to ground, depending on the design of the switch.

Switch at power window down

Pressing the switch to lower a power window, directs current to one wire and grounds

the other wire. Direct current flow in this position causes the motor to rotate and lower

the power window. Back probing the connector will show 12 volts between the two

wires and -12 volts if we reverse our test leads.

Switch at power window up

To raise the power window, we push the switch in the opposite direction. This reverses

the polarity of current flow within the switch. In other words, the terminal that has 12

volts in the lowering position has become the ground in the raising position. The lead

that grounds the motor when lowering the window becomes the current source when

we raise the window.

By reversing the current flow to the motor, we cause it to rotate in the opposite

direction. Turning one way will lower the window and rotating in the other direction will raise the power window.

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5. Explain the rectification process to correct the faults; include the selection and preparation of

any equipment used, the correction procedure (unit replacement or adjustment) and the

evaluation of the repaired system to confirm performance. (10 marks) AC (5.4, 5.6, 5.7)

5.4 Explain how to carry out the rectification activities in order to correct the faults in the

automotive auxiliary electrical systems

5.6 Explain how to evaluate and interpret test results found in diagnosing automotive auxiliary

electrical system faults against vehicle manufacturer specifications and settings

5.7 Explain how to evaluate the operation of components and systems following diagnosis and

repair to confirm system performance

Electrical window:

After gone through the diagnosed with symptom no power supply to the window power motor.

Possible cause will be blown fuse or relay. So we can verify it with several test on the fuse or

relay with the help of multimeter for resistance test for both fuse and relay unit (electric

window).

Continue ………

sample answer ae06

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