Actron AutoAnalyzer CP7665 - Manual (Page 6)

6
Setting the Range
Two of the most commonly asked
questions about digital multimeters
are What does Range mean? and
How do I know what Range the mul-
timeter should be set to?
What Does Range mean?
Range refers to the largest value
the multimeter can measure with
the rotary switch in that position. If
the multimeter is set to the 20V DC
range, then the highest voltage the
multimeter can measure is 20V in
that range.
EXAMPLE: Measuring Vehicle Bat-
tery Voltage (See Fig. 1)
the display. If you are in the highest
range and the multimeter is still
showing that it is overranging, then
the value being measured is too
large for the multimeter to measure.
How do I know what Range the
multimeter should be set to?
The multimeter should be set in the
lowest possible range without
overranging.
EXAMPLE: Measuring an unknown
resistance
Let’s assume the multimeter is con-
nected to an engine coolant sensor
with unknown resistance. (See Fig. 3)
Start by setting the multimeter to the
largest OHM range. The display
reads 0.0
Ω
or a short circuit.
Fig. 2
Fig. 1
Let’s assume the multimeter is con-
nected to the battery and set to the
20V range.
The display reads 12.56. This means
there is 12.56V across the battery
terminals.
Now assume we set the multimeter
to the 2000mV range. (See Fig. 2)
The multimeter display now shows
a “1” and nothing else. This means
the multimeter is being overranged
or in other words the value being
measured is larger than the current
range. The range should be in-
creased until a value is shown on
Fig. 3
Red
Black
Red
Black
Black Red