jcb JS300 Service Manual page 432

plugged into the black socket (sometimes, this socket
is also marked by a "-", or "E" or marked as
"COMMON" or "COM"). The red test lead should be
plugged into the red socket marked with "+", "V" or
Ω
" ".
2 When making measurements ensure that the test
probes have a good clean contact with bare metal,
free from grease, dirt, and corrosion as these can
cause a false reading.
3 When measuring voltage: Make sure that the correct
range is selected, that is set the selector to a value
equal to or greater than that you are about to
measure. e.g. If asked to measure 12 Volts, set the
selector to the 12V range. If there is no 12V range, set
the selector to the next range higher, 20V for
instance. If the meter is set to a range that is too low,
it may be damaged. e.g. setting to the 2V range to
measure 12V.
Measuring DC Voltage
1 Select the correct range on the multimeter.
a On the FLUKE 85.
Turn the switch to position 9-B.
b On the AV0 2003.
Move the right slider switch to position 10-A, and
the left hand slider switch to the appropriate
range.
c On an analogue meter.
Turn the dial to the appropriate DC Volts range.
2 Connect the black probe to the nearest available
suitable earth point, usually this will be the starter
motor earth, the battery negative, or the chassis.
Connect the red probe to the wire or contact from
which you are measuring the voltage.
C-7
Measuring Resistance
1 Make sure there is no power to the part of the circuit
you are about to measure.
2 Connect one probe at one end of the component or
wire to be checked and the other probe at the other
end. It does not matter which way round the two
probes are placed.
3 Select the correct range on the multimeter.
a On the FLUKE 85.
i Turn the switch to position 9-C and check that
the W sign at the right hand side of the display
window is on. If the F sign is on instead, press
the blue button 9-G to change the reading to
Ω
. Touch the meter lead probes together and
press the REL
the lead resistance from the meter reading.
b On the AV0 2003.
i Move the right hand slider switch to position
10-B, and the left hand slider switch to the
appropriate Ohms (
c On an analogue meter.
i Move the dial to the appropriate Ohms (
range.
9813/5100-1
Section C - Electrics
Overview and Schematics
Using a Multimeter
3 key on the meter to eliminate
Ω
) range.
Ω
)
C-7