Subaru 2009 IMPREZA, Service Manual

Page: 3423 / 3619

WI-4
Basic Diagnostic Procedure
WIRING SYSTEM
3) The symbol “ — ” indicates that continuity
exists between two points or terminals. For exam-
ple, when a switch position is at “3”, continuity ex-
ists among terminals 1, 3 and 6, as shown in the
table below.
3. HOW TO DETERMINE AN OPEN CIRCUIT
1) WITH VOLTMETER:
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.
2) WITH OHMMETER:
Disconnect all connectors affected, and check con-
tinuity in the wiring between adjacent connectors.
When the ohmmeter indicates “infinite”, the wiring
is open.
4. HOW TO DETERMINE A SHORT CIRCUIT
1) WITH TEST LIGHT:
Connect a test light (rated at approx. 3 watts) in
place of the blown fuse and allow current to flow
through the circuit. Disconnect one connector at a
time from the circuit. Starting with the one located
farthest from the power supply. If the test light goes
out when a connector is disconnected, the wiring
between that connector and the next connector
(farther from the power supply) is shorted.
2) WITH OHMMETER:
Disconnect all affected connectors, and check con-
tinuity between each connector and ground. When
the ohmmeter indicates continuity between a par-
ticular connector and a ground, that connector is
shorted.
Terminal
Switch Position
OFF
1
2
3
4
1
2 3 4
5 6
WI-02741
Open circuit or wiring
12V
V V
0V
WI-02742
Open circuit
WI-09860
Shorted wiring
Test light
Fuse holder
WI-02744
Shorted connector
WI-02745