check engine SUBARU LEGACY 1996 Service Repair Manual

B: CHECK LIST FOR INTERVIEW
Check the following items about the vehicle’s state.
1. THE STATE OF THE WARNING LIGHTS
a. ABS warning light

1Is always on.2Sometimes comes on.3Comes on only once.4Does not come on.
When/how long does it come on?
Ignition key
position
1Lock2Acc3On (before starting engine)4Start5On after starting (Engine: run)
6On after starting (Engine: stop)
Timing
1Immediately after ignition is on.2Immediately after ignition starts.
3When advancing (Speedmiles/h,miles/h)4While traveling at a constant speed (Speedmiles/h)
5When decelerating (Speedmiles/h,miles/h)
6When turning (To right, to left, steering angledeg., steering timesec)
7When other electrical parts move (Part name:, Operating condition)
8When moving other electrical parts (Part name:, Operating condition)
b. TCS warning light

1Is always on.2Sometimes comes on.3Comes on only once.4Does not come on.
When does it come on?
Ignition key
position
1Lock2Acc3On (before starting engine)4Start5On after starting (Engine: run)
6On after starting (Engine: stop)
Timing
1Immediately after ignition is on.2Immediately after ignition starts.
3When advancing (Speedmiles/h,miles/h)4While traveling at a constant speed (Speedmiles/h)
5When decelerating (Speedmiles/h,miles/h)
6When turning (To right, to left, steering angledeg., steering timesec)
7When other electrical parts move (Part name:, Operating condition)
8When moving other electrical parts (Part name:, Operating condition)
c. TCS OFF indicator light

1Is always on.2Sometimes comes on.3Comes on only once.4Does not come on.
When/how long does it come on?
Ignition key
position
1Lock2Acc3On (before starting engine)4Start5On after starting (Engine: run)
6On after starting (Engine: stop)
Timing
1Immediately after ignition is on.2Immediately after ignition starts.
3When advancing (Speedmiles/h,miles/h)4While traveling at a constant speed (Speedmiles/h)
5When decelerating (Speedmiles/h,miles/h)
6When turning (To right, to left, steering angledeg., steering timesec)
7When other electrical parts move (Part name:, Operating condition)
8When moving other electrical parts (Part name:, Operating condition)
d. TCS operation indicator light

1Is always on.2Sometimes comes on.3Comes on only once.4Does not come on.
When does it come on?
Ignition key
position
1Lock2Acc3On (before starting engine)4Start5On after starting (Engine: run)
6On after starting (Engine: stop)
Timing
1Immediately after ignition is on.2Immediately after ignition starts.
3When advancing (Speedmiles/h,miles/h)4While traveling at a constant speed (Speedmiles/h)
5When decelerating (Speedmiles/h,miles/h)
6When turning (To right, to left, steering angledeg., steering timesec)
7When other electrical parts move (Part name:, Operating condition)
8When moving other electrical parts (Part name:, Operating condition)
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6. Diagnostics Chart for On-board Diagnosis System

7. Diagnostics Chart for Warning Light
Circuit Failure
A: TROUBLE CODE DOES NOT APPEAR.
—TCS WARNING LIGHT COMES ON WHEN
STARTING THE ENGINE.—
1. Check TCS warning light.
OK
Not OK
Repair harness.
2. Check diagnosis terminal.
OK
Not OK
Repair harness.
3. Check diagnosis connector.
OK
Not OK
Repair harness/connector.
Replace ABS/TCS control module.
B4M0385



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7. Diagnostics Chart for Warning Light Circuit Failure

B: ABS AND TCS WARNING LIGHT DO NOT
GO OFF.
—TCS OFF AND TCS OPERATING
INDICATOR LIGHTS COME ON AND GO OFF
PROPERLY WHEN STARTING THE ENGINE,
WHILE ABS WARNING AND TCS WARNING
LIGHTS KEEP ON.—
1. Check brake fluid level.
OK
Not OK
Add to brake fluid.
2. Check brake fluid level sensor.
OK
Not OK
Replace master cylinder.
3. Check harness connector between ABS/TCS
control module and alternator.
OK
Not OK
Replace harness connector.
Replace ABS/TCS control module.
B4M0389



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7. Diagnostics Chart for Warning Light Circuit Failure

1. CHECK BRAKE FLUID LEVEL.
Check that brake fluid level is above the MIN indication on
the reservoir tank.
B4M0716A
2. CHECK BRAKE FLUID LEVEL SENSOR.
1) Turn ignition switch OFF.
2) Disconnect connector from brake fluid level sensor.
Connector & terminal / Specified resistance:
(B16) No. 1—No.2/0Ω(Leaving float where it
is.)
(B16) No. 1—No.2/1MΩ(When pushing float
down.)
B4M0717A
3. CHECK HARNESS CONNECTOR BETWEEN ABS/
TCS CONTROL MODULE AND ALTERNATOR.
1) Turn ignition switch OFF.
2) Connect connector from brake fluid level sensor.
3) Disconnect all connectors from ABS/TCS control mod-
ule.
4) Measure voltage between ABS/TCS control module
connector and body.
Connector & terminal / Specified voltage:
(P7) No. 20—body/2Vorless
5) Start the engine.
6) Measure voltage between ABS/TCS control module
connector and body.
Connector & terminal / Specified voltage:
(P7) No. 20—body / 10—14 V
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7. Diagnostics Chart for Warning Light Circuit Failure

C: TCS WARNING LIGHT AND TCS
INDICATOR OFF AND TCS OPERATING
INDICATOR LIGHTS COME ON AND GO OFF
PROPERLY, WHILE ABS WARNING LIGHT
DOES NOT GO OFF.
—TCS WARNING LIGHT AND TCS OFF
INDICATOR AND TCS OPERATING
INDICATOR LIGHTS COME ON AND GO OFF
PROPERLY WHEN STARTING THE ENGINE,
WHILE ABS WARNING LIGHT DOES NOT GO
OFF.—
1. Check harness connector between ABS/TCS
control module and ABS warning light.Repair harness connector.
Replace ABS/TCS control module.
B4M0392

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7. Diagnostics Chart for Warning Light Circuit Failure

D: ABS WARNING LIGHT ONLY REMAINS
ILLUMINATED.
—WHEN STARTING THE ENGINE, NEITHER
TCS WARNING, TCS OFF INDICATOR NOR
TCS OPERATING INDICATOR LIGHT COMES
ON EVEN ONCE, AND ABS WARNING LIGHT
AND MALFUNCTION INDICATOR LAMP
ILLUMINATE.—
1. Check input voltage of ABS/TCS control mod-
ule.
OK
Not OK
Repair harness/connector.
Replace ABS/TCS control module.
B4M0394

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7. Diagnostics Chart for Warning Light Circuit Failure

E: TCS OFF INDICATOR LIGHT DOES NOT
GO OFF.
—ABS WARNING, TCS WARNING AND TCS
OPERATING INDICATOR LIGHTS COME ON
AND GO OFF PROPERLY WHEN STARTING
THE ENGINE, BUT TCS OFF INDICATOR
DOES NOT GO OFF FOR MORE THAN 30
SECONDS AFTER ENGINE RUNNING.—
Does malfunction indicator lamp (Check engine
lamp) come on?
No
Ye s
Conduct OBD II diagnosis.

1. Check harness connector between ABS/TCS
control module and TCS OFF indicator light.
OK
Not OK
Repair harness/connector.
Replace ABS/TCS control module.
B4M0396


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7. Diagnostics Chart for Warning Light Circuit Failure

F: TCS OPERATING INDICATOR LIGHT DOES
NOT GO OFF.
—WHEN STARTING THE ENGINE, ABS
WARNING, TCS WARNING AND TCS OFF
INDICATOR LIGHTS COME ON AND GO OFF
PROPERLY BUT TCS OPERATING
INDICATOR LIGHT ONLY KEEPS ON.—
1. Check harness connector between ABS/TCS
control module and TCS operating indicator
light.
OK
Not OK
Repair harness/connector.
Replace ABS/TCS control module.
B4M0398

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7. Diagnostics Chart for Warning Light Circuit Failure

G: TCS OFF SWITCH DOES NOT FUNCTION.
—TCS OFF INDICATOR LIGHT COMES ON
AND GOES OFF PROPERLY WHEN
STARTING THE ENGINE, WHILE THIS LIGHT
NEITHER COMES ON NOR GOES OFF WHEN
PUSHING THE TCS OFF SWITCH.—
1. Check TCS OFF switch
OK
Not OK
Replace TCS OFF switch.
2. Check harness connector between ABS/TCS
control module and TCS OFF switch.
OK
Not OK
Repair harness/connector.
Replace ABS/TCS control module.
B4M0535


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7. Diagnostics Chart for Warning Light Circuit Failure

5. CHECK SOURCES OF SIGNAL NOISE.
1) Check that the mobile phone, personal radio and other
wireless apparatus are correctly installed.
2) Check that the antenna and other possible noise
sources are distant enough from the sensor harness.
3) Check that the sealed wires of the front harness sensor
(in the engine room) are securely grounded.
4) Check that between ABS/TCS control module and the
rear sensor harness has the correct twist pitch.
Twist pitch:
25 mm (0.98 in) or less
6. CHECK HYDRAULIC UNIT OPERATIONS.
1) Operate the ABS sequence control and check that the
brake fluid pressure at the malfunctioning brake line
increases and decreases properly.
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8. Diagnostics Chart with Trouble Code