Vehicle Electrical & Electronic Diagnosis Quiz

Frequency relates to how many cycles per second
1 Hertz = 1 cycle per second

PWM is an electronic conrol of a motor, bulb or solenoid etc. Instead of reducing the supply voltage the voltage is pulsed on and off; this gives a drop in the average voltage over a fixed time frame hence the consumer/motor would spin slower if the average voltage has been reduced.

NTC is sometimes refferred to as Negative Thermal Coefficient which relates to how the resistance level drops the temperature is increasing often used in sensor technology for cooling fans/gauges etc.

The High resistance often caused by corrosion would restrict the current flow this in turn would reduce the power being available to the consumer, in this case lamp units and give a dim lamp.

This is often abrievieated to PTC

Voltage drop in a circuit will obviously effect the performance of the consumer within that circuit if it is receiving less voltage due to a high resistance in the supply wire. This would lead to slow motor operation, dim lamps etc.Anything more than 0.5 Volts would be a cause for concern. On an earth circuit this would be as low as 0.25 volts.

This type of sensor would produce an AC sine wave. As speed increases the wave form would come closer together and the peak to peak voltage would increase. Giving an increased amplitude and frequency.

The digital square wave pattern gives us either an on or an off signal there is no signal voltage in between as with an analogue signal.

An easy way to remember is X is a cross so by default Y must be vertical the longer you go across the longer time it will take. And if linked to an AC sensor output the voltage goes up and down dependent on speed and position so the voltage/amplitude is on the vertical axis

When using an Ammeter for testing current flow either in operation or an excessive drain check it must be connected in series with the circuit being tested. The circuit needs to be complete as current will not flow. If connected in parallel you will damage the multimeter.

The Zener Diode or Avalanche diode will hold back the pressure or voltage up until a certain point or its Zener Voltage the it will allow it to pass in the reverse direction. As soon as the voltage drops below the Zener Voltage the diode retains the pressure again preventing the current from flowing in the reverse direction

First finger relates to the direction of the magnetic field North to South
Second finger relates to the direction of the current flow positive to negative
Thumb relates to the movement of the wire

The first finger represents the direction of the magnetic field from North to South
The second finger reprents the direction of induced current from positive to negative
The thumb represents the motion of the conductor

Voltage drop is the decrease in voltage across a component in a circuit due to resistance. To measure voltage drop, the meter must be connected in parallel with the component while the power supply is on. This allows the meter to measure the difference in voltage between the two points across the component.

It is important to disconnect the power supply as this could effect your reading and if an electronic unit could damage another component within the system. Always connect the meter in parallel to the test component with the meter set to Ohms.

When connecting an ammeter it needs to be wired in series so the current can flow through the meter this is best done on the earth return side of the battery.