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drawn from the battery under
high load conditions.
A voltage drop is measured
dynamically (when current fl ows
through the circuit). Both open
circuit voltage and voltage drop
testing have their place in the
diagnostic process. Information
from each measurement can be
helpful if used appropriately.
Voltage drop is one of the most
useful tests you can perform. A
voltage drop test isolates voltage
used in the portion of the circuit
being tested. A voltage drop test
is performed as follows:
• Place the positive lead in the
most positive section of the circuit
you are testing.
• Place the ground lead on the
most negative section of the
circuit you are testing.
• Operate the circuit with the
meter leads in place and note the
reading.
Typical voltage drops are as
follows:
• Across a switch, relay contacts
The meter leads in this fi gure
show three different ways to
measure voltage.
or connector: Less than 100 mV
(