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Duty cycle measured in percent of high or low time or dwell degrees
(mixture control solenoid)
Duty Cycle, What is it ?
Duty cycle is the
percentage (%)
of time
a voltage is positive
compared to negative:ON
compared to OFF. For example;
duty cycle measurements are
used for Mixture control solenoids.
The amount of ON time is
measured as a percent of the total
ON/OFF cycle. The meter can
read the negative (-) or positive (+)
slope and display it as a percent (%) of the total cycle.
Frequency (Hz), What is it?
Frequency is the number of times a voltage pattern repeats positive compared
to negative: ON compared to OFF,
during one (1) second of time. For
example: frequency(Hz)
measurements are specified for
digitally controlled manifold
Absolute Pressure sensors. The
frequency of the ON/OFF signals
per second are measured and
displayed.
Frequency(Hz) is shown as
Analog
: A continuous positive to
negative cycle; or
Digital
: A
positive to negative/ON to OFF
cycle.
Pulse Width. What is it?
Pulse width is the
length of time
an actuator is energized. For example; fuel injectors are activated by an
electronic pulse from the engine control module. This pulse generates a
magnetic field that pulls the injector nozzle valve open. The pulse ends and the
injector nozzle is closed. This
“open to close” time is the pulse width and is
measured in milliseconds (mS).
Typical Port fuel injectors(TBI) operate with a single ON to OFF electrical
pulse.
Typical Port Throttle Body injectors (TBI) operate with an ON to HOLD to OFF
electrical pulse. This method creates a double electrical
“spike”. An
oscilloscope is required to measure this type of pulse.
Component Tests (input)
[1] Temperature Tests
Many components that regulate temperature can be tested be measuring the
surface temperature of the area surrounding the component.
·
Connect the temperature probe to the meter.
·
Set the rotary switch to the
Temperature
position.
·
Touch the end of the temperature probe directly to the surface of the
component to be tested.
Compare your readings with the manufactures Specifications. The temperature
should be within
±
10
℉
(
±
5
℃
) of the data stream Values.
Some of the components that can be tested for Temperature variation are:
·
Radiators
·
Transmission
·
Heaters
·
A/C Condensers
·
A/C Evaporators
·
Engine Coolant Sensors
·
Air Temperature Sensors
[2] Thermistor (Variable Resistance, 2-wire) Tests
Thermistor are variable resistors that are sensitive to temperature level
changes. As the temperature changes, the thermistor
’s resistance value
changes.
·
Select the
Ohms
(
Ω
) range the rotary switch .
·
Connect the test probes to the sensor terminals.
The Ohms reading should match the temperature of the sensor (see
manufacturer
’s specifications).
