Subaru Impreza 2002 Service Manual page 5

I
BASIC DIAGNOSTICS PROCEDURE
WIRING SYSTEM
3. HOW TO DETERMINE AN OPEN CIR-
CUIT
1) Voltmeter Method:
An open circuit is determined by measuring the
voltage between respective connectors and ground
using a voltmeter, starting with the connector clos-
est to the power supply. The power supply must be
turned ON so that current flows in the circuit. If volt-
age is not present between a particular connector
and ground, the circuit between that connector and
the previous connector is open.
NO voltage is present
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Voltage is present
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2) Ohmmeter method:
Disconnect all connectors affected, and check con-
tinuity in the wiring between adjacent connectors.
When the ohmmeter indicates "infinite", the wiring
is open.
7\
Open circuit
1 1
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Continuity exists.
Continuity does not exist.
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4. HOW TO DETERMINE A SHORT CIR-
CUIT
1) Test lamp method:
Connect a test lamp (rated at approximately 3
watts) in place of the blown fuse and allow current
to flow through the circuit. Disconnect one connec-
tor at a time from the circuit, starting with the one lo-
cated farthest from the power supply. If the test
lamp goes out when a connector is disconnected,
the wiring between that connection and the next
connector (farther from the power supply) is short-
ed.
Test lamp
-&
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2) Ohmmeter method:
Disconnect all affected connectors, and check con-
tinuity between each connector and ground. When
the ohmmeter indicates continuity between a par-
ticular connector and ground, that connector is
shorted.
, -
Shorted connector
pl
Continuity
qq
exists.
t-
-
Continuity does not exist.
. I -
G6M0211
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