TM 10-5410-221-14/1
CHAPTER 11
MATERIAL USED IN CONJUNCTION WITH MAJOR ITEM
2. If the needle doesn't move, the circuit is
11-1. General
open (broken).
This chapter contains information on the use of
3. If the needle jumps or flickers there is a
multimeters.
loose connection in the circuit being tested.
11-2. General Instructions for Use of Multimeters
(3) Testing for shorts. A short (or short circuit)
a. Introduction.
In electrical troubleshooting, the
occurs when two circuits that should not be connected
Simpson 160, the TS-352B/U, and. The AN/URM-105
have metal to metal contact with each other. A short
will do the same job. Therefore, your shop sets may
also occurs when a circuit that should not touch ground
contain any one of these multimeters (fig. 11-1). Any of
has metal to metal contact with ground. To check for
these three multimeters can be used to troubleshoot your
shorts, do the following steps:
equipment's electrical system. This section shows how.
(a) Set up and "zero" the multimeter (fig. 11-2).
NOTE
CAUTION
The Simpson 160 is only available in
Failure to do the following step can
new shop sets as a substitute for the
damage the multimeter.
TS-325B/U or AN/URM-105.1180
(b) Disconnect the circuit being tested. To be
b. Using the Ohms Scale. The ohms scale is used to
safe, disconnect the battery ground strap.
(c) With all three multimeters, connect one probe
(1) "Zeroing" the meter (fig.11-2). The multimeter
to one circuit and the other probe to the other circuit or
must be set up and "zeroed" before making these tests.
ground (if checking for a short to ground). The example
Do the following steps that match the multimeter you
below (fig.1 1-4) shows a check to see if wire "A" is
have:
shorted to wire "B" in the wiring harness.
(2) Continuity tests. Continuity tests are made to
(d) Look at the needle.
check for breaks in a circuit (such as the switch light
1. If the needle swings to the far right over
bulb, or electrical cable) (fig. 11-3). To make a
the "0" on the top scale (on all three multimeters), the
continuity check, do the following steps:
circuits are shorted.
(a) Set. up and , "zero" the multimeter (fig. 11-
2. If the needle doesn't move, the circuits are
2).
not shorted.
CAUTION
3. If the needle jumps or flickers, the circuits
Failure to do the following step can
are occasionally shorted.
damage the multimeter.
(4) Testing resistance. To measure resistance in a
(b) Disconnect the circuit being tested. To be
circuit, do the following steps:
safe, disconnect the battery ground strap.
(a) Set up and "zero" the multimeter (fig. 11-2).
(c) Connect the meter probes to both terminals
CAUTION
of the circuit being tested. (The TS-352B/U is illustrated
Failure to do the following step can
(fig. 11-3), but the probes are connected to the circuit
damage the multimeter.
the same way with all three multimeters.
(d) Look at the meter needle.
(b) Disconnect the circuit being tested. To be
1. If the needle swings to the far right over
safe, disconnect the battery ground strap.
the "0" on the top scale (on all three multimeters), the
circuit has continuity.
11-1