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B0M0014A
Connectors equipped with shock protectors must be
checked with a mini probe (thin), or it will be necessary to
remove the shock protector.
B0M0015A
When the connector has a back plate, remove the plate
after removing the projection of the plate first. (Be careful not
to use excessive force, since the terminals might brake off.)
B0M0016A
C: CHECKING FOR POOR CONTACT ON
PLUG-IN CONNECTORS
1. POOR CONTACT
Poor contact is frequently caused by corroded terminals, dirt,
foreign substances, weak contact points between male and
female connectors, etc. Quite often a plug with poor contact
will work perfectly again after it has been pulled off and recon-
nected. If harness and connector checks do not reveal any
defect, it can be assumed that an intermittent contact in a
connector is the source of trouble.
B0M0017A
2. VISUAL INSPECTION
1) Disconnect the two connector halves.
2) Check the connector pins for signs of corrosion or foreign
material.
3) Check the connector for loose and damaged terminals,
and make sure they are set correctly in the connector.
NOTE:
When the harness is pulled lightly, the terminals should not
come out.
B0M0018A
4) Insert the male pin of the connector into the female pin,
then pull it out.
NOTE:
If one of the pins allows to pull out easily, it is a likely source
of a malfunction.
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[T3C2] FOREWORDFOREWORD
3. Basic Checks
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B0M0019A
5) Shake lightly the connector and the harness, and check for
sudden changes in voltage or resistance.
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3. Basic Checks
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B0M0020
4. Diagnosis and Checking Procedure
Using Instruments
A: USING A CIRCUIT TESTER
1. VOLTAGE CHECK (range set to DC V)
Connect the positive probe to the terminal to be tested, and
the negative probe to body ground. (or the ground terminal of
the ECM)
B0M0021
2. CHECKING THE CONNECTION (range set toΩ)
Measure the resistance and check for open or shorted wire in
the harness or the connector.
NOTE:
This check must be carried out with both connectors discon-
nected.
(This avoids by-passing the connection through other cir-
cuits.)
1) Check for open circuit. (range:Ωx 1K)
Measure the resistance between the respective pins in both
connectors.
Specified resistance:
More than 1 MΩ(No continuity) Open circuit
Less than 10Ω(Continuity) O.K.
2) Check for correct insulation value. (range:Ωx 1K)
Measure the resistance between the pins in both connectors,
as well as between the suspected pin and the body. (body
short)
Specified resistance:
More than 1 MΩ(No continuity) O.K.
Less than 10Ω(Continuity) Short circuit
3) Resistance measurement (range set toΩ)
Measuring the internal resistance of sensors, solenoid valves
etc. to check the operating condition of components.
NOTE:
Select the appropriate range for measuring the internal
resistance, or the measurement will result in an incorrect
reading.
Before changing the measurement range the gauge must
be reset to zero.
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4. Diagnosis and Checking Procedure Using Instruments
Page 3340 of 3342

B: USING A SUBARU SELECT MONITOR
With this testing procedure the defective component can be
determined by directly monitoring input/output signals of the
ECM or the trouble codes.
1. FEATURES
A variety of data can be checked without movements from
the drivers seat, passenger’s seat or from outside the vehicle.
This unit allows the identification of the type of malfunction,
for example whether the cause is an open or shorted wire in
the input/output signal line, or whether the breakdown of a
component is caused by a lack of maintenance.
2. DIAGNOSIS
Refer to the reference values for input/output and control
data to determine whether the malfunction is caused by a
worn out component, an open wire, a short etc.
Perform the diagnostics procedure as described in chapter
“Check based on trouble codes”by monitoring the trouble
codes.
NOTE:
It will be easier to determine a malfunction if the vehicle data
for normal conditions are available for comparison.
G2H0054
3. CONNECT SELECT MONITOR.
1) Connect select monitor to data link connector located
under instrument panel. (on driver’s side)
G3M0150
2) Insert cartridge into select monitor.
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4. Diagnosis and Checking Procedure Using Instruments
Page 3341 of 3342
![SUBARU LEGACY 1997 Service Repair Manual G3M0151
3) Turn ignition switch and select monitor switch ON.
4) After display is shown, press slash“/”key.
5) After AT mode is displayed, press function“[0]”.
(Display returns to AT mode when SUBARU LEGACY 1997 Service Repair Manual G3M0151
3) Turn ignition switch and select monitor switch ON.
4) After display is shown, press slash“/”key.
5) After AT mode is displayed, press function“[0]”.
(Display returns to AT mode when](/manual-img/17/57434/w960_57434-3340.png)
G3M0151
3) Turn ignition switch and select monitor switch ON.
4) After display is shown, press slash“/”key.
5) After AT mode is displayed, press function“[0]”.
(Display returns to AT mode when slash“/”is pressed during
on-board diagnostic operation.)
G3M0152
4. READ TROUBLE CODE SHOWN ON DISPLAY.
1) Connect select monitor.
2) Designate mode using function key.
Press [F] [B] [0] [ENT] in that order.
3) Ensure trouble code(s) is shown.
G3M0152
5. PREVIOUS TROUBLE CODE READING
1) Connect select monitor.
2) Designate mode using function key.
Press [F] [B] [1] [ENT] in that order.
3) Ensure displayed trouble code(s).
C: USING AN OSCILLOSCOPE
A malfunction can be determined by displaying the waveforms
of input/output signals on the oscilloscope.
1. DIAGNOSIS
A simple comparison of the waveforms may lead to an incor-
rect diagnosis. To exactly determine the sources of the mal-
function it will be necessary to determine them under consid-
eration about information other than waveforms.
2. APPLYING INPUT/OUTPUT SIGNALS
Connect the probe directly with the terminal of the signal.
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[T4C2] FOREWORDFOREWORD
4. Diagnosis and Checking Procedure Using Instruments
Page 3342 of 3342
Important safety notice
Providing appropriate service and repair is a matter of great importance in the serviceman’s safety maintenance
and safe operation, function and performance which the SUBARU vehicle possesses.
In case the replacement of parts or replenishment of consumables is required, genuine SUBARU parts whose
parts numbers are designated or their equivalents must be utilized.
It must be made well known that the safety of the serviceman and the safe operation of the vehicle would be
jeopardized if he used any service parts, consumables, special tools and work procedure manuals which are
not approved or designated by SUBARU.
All right reserved. This book may not be reproduced
or copied, in whole or in part, without the written
permission of FUJI HEAVY INDUSTRIES LTD.,
TOKYO JAPAN.
SUBARU,
andare trademarks of
FUJI HEAVY INDUSTRIES LTD.
© Copyright 1996 FUJI HEAVY INDUSTRIES LTD.
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