SUBARU LEGACY 1996 Service Repair Manual

3. LIST OF ABS/TCS ON-BOARD DIAGNOSTICS
FUNCTIONS
Trouble codeDiagnostic items
<detailed diagnostic items>Detection timingIndicator
light ON
Parts concerned
At initial checking
Under no control
Under ABS control
Under TCS control
In diagnostic mode
ABS warning light
TCS warning light
TCS OFF indicator light
21 FR
23 FL
25 RR
27 RLDetection of fault in ABS sensor hardware
<open/short circuits of sensor>
 —ABS sensor (ABS/TCS C/M)
22 FR
24 FL
26 RR
28 RLDetection of fault in ABS sensor software
<variations in wheel speed> —ABS sensor (ABS/TCS C/M)
 —ABS sensor harness circuit (ABS/TCS C/M)
Detection of fault in ABS sensor software
<decompression mode>—ABS sensor and solenoid valve (ABS/TCS C/M)
—ABS sensor (ABS/TCS C/M)
Detection of fault in sensor software
<speed higher than prescribed> —ABS sensor (ABS/TCS C/M)
31 FRI
32 FRO
33 FLI
34 FLO
35 RRI
36 RRO
37 RLI
38 RLO
61 TCS1
62 TCS2Abnormal valve
<Abnormal valve>
*
—Solenoid valve (ABS/TCS C/M)
41 Abnormal ABS/TCS C/M
<Abnormal ABS/TCS C/M> —ABS/TCS C/M
42 Abnormal line voltage
<Abnormal line voltage>—Power source operating environment (ABS/TCS C/M)
—Power source voltage drop
<Power source voltage drop> —
—
*: Except when trouble code is being displayed.
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5. Control Module I/O Signal

Trouble codeDiagnostic items
<detailed diagnostic items>Detection timingIndicator
light ON
Parts concerned
At initial checking
Under no control
Under ABS control
Under TCS control
In diagnostic mode
ABS warning light
TCS warning light
TCS OFF indicator light
43 Abnormal EGI communication line
<Abnormal EGI communication line>——AET communication line (ABS/TCS C/M)
——
——
——AEB communication line (ABS/TCS C/M)
——
——
——AEC communication line (ABS/TCS C/M)
——
——
—Abnormal EGI communication line
<Abnormal EGI communication line>——EAM communication line (ABS/TCS C/M)
51 Abnormal valve relay
<failure of valve relay ON>
<failure of valve relay OFF>—Valve relay (ABS/TCS C/M)
Abnormal valve relay
<failure of valve relay OFF> —Valve relay (ABS/TCS C/M)
 —
52 Abnormal motor system
<failure of motor relay OFF> —Motor (ABS/TCS C/M)
Abnormal motor system
<failure of motor relay ON> —Motor (ABS/TCS C/M)
Abnormal motor system
<failure of motor relay OFF>—
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5. Control Module I/O Signal

Trouble codeDiagnostic items
<detailed diagnostic items>Detection timingIndicator
light ON
Parts concerned
At initial checking
Under no control
Under ABS control
Under TCS control
In diagnostic mode
ABS warning light
TCS warning light
TCS OFF indicator light
54 Abnormal pedal stroke sensor and stop light switch
<open/short circuits of stroke sensor> —Pedal stroke sensor (ABS/TCS C/M)
Abnormal pedal stroke sensor and stop light switch
<comparison of acceleration and stroke sensor>—Pedal stroke sensor (ABS/TCS C/M)
Abnormal pedal stroke sensor and stop light switch
<comparison of stroke sensor and brake lamp switch>—Stop light switch, pedal stroke sensor (ABS/TCS C/M)
Abnormal pedal stroke sensor and stop light switch
<comparison of stroke sensor and pump exitation>—Pump, pedal stroke sensor (ABS/TCS C/M)
Abnormal stroke sensor and stop light switch
<open circuit of stop light switch>——Stop light switch circuit (ABS/TCS C/M)
57 Abnormal fluid level sensor
<Abnormal fluid level sensor>—Fluid level sensor circuit
—Abnormal fluid level sensor
<Abnormal fluid level sensor>
<Insufficient brake fluid> —Fluid level sensor circuit, reservoir
58 Abnormal pressure switch
<Abnormal pressure switch>——Pressure switch (ABS/TCS C/M)
——Pressure switch, stop light switch (ABS/TCS C/M)
——Pressure switch (ABS/TCS C/M)
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5. Control Module I/O Signal

6. Diagnostics Chart for On-board
Diagnosis System
A: BASIC DIAGNOSTICS PROCEDURE
TROUBLE OCCURS.
Ask the customer when and how the
trouble occurred using interview
check list. <Ref. to 4-4b [T6B0].>
PRE-INSPECTION
<Ref. to 4-4b [T200].>
INSPECTION MODE
<Ref. to 4-4b [T6C0].>
CALLING UP A TROUBLE CODE.
<Ref. to 4-4b [T6D1].>No trouble code is readable.

Inspection using Diagnostic Chart for
Warning Light Failure.
<Ref. to 4-4b [T700].>
Record all trouble codes.
Trouble codes
are issued.
Only the start code is issued.
Inspection using General Diagnostics
Chart
<Ref. to 4-4b [T1100].>
Perform diagnostics in accordance with trouble code.
<Ref. to 4-4b [T8A0].>
Trouble code
designated.

Repair.
Clear memory.
<Ref. to 4-4b [T6D2].>
INSPECTION MODE
<Ref. to 4-4b [T6C0].>
CALLING UP A TROUBLE CODE.
<Ref. to 4-4b [T6D1].>
Only the start code is issued.
CONFIRMATION TEST
END
NOTE:

To check harness for broken wires or short circuits,
shake it while holding it or the connector.

When TCS warning light illuminates, read and record
trouble code indicated by TCS warning light.












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6. Diagnostics Chart for On-board Diagnosis System

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

e. Malfunction 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)
2. SYMPTOMS
ABS operating
condition1Performs no work.2Operates only when abruptly applying brakes. (Conditions: vehicle speedmiles/h, how to step
on brake pedal)
3Operating time (sec., etc.)4Operating noise (Produced/Not produced)
5What kind of noise? (Knock, gong gong, bong, buzz, gong gong buzz, etc.)
6Reaction force of brake pedal (Stick, pressed down once with a clunk, pressed and released, etc.)
TCS operating
condition
1Performs no work.2Operates only when abruptly accelerating. (Conditions: vehicle speedmiles/h, how to step on
accelerator pedal)
3Operating time (sec., etc.)4Operating noise (Produced/Not produced)
5What kind of noise? (Knock, gong gong, bong, buzz, gong gong buzz, etc.)
6Whether or not operation indicator light comes on. (Come on/Does not come on, Others)
Behavior of
vehicle
1Directional stability cannot be obtained or steering arm refuses to work when applying brakes (vehicle turns to right, turns
to left, spins, etc.).
2Directional stability cannot be obtained or steering arm refuses to work when accelerating (vehicle turns to right, turns to
left, spins, etc.).
3Brakes are out of order (braking distance is long, brakes lock or drag, pedal stroke is long, pedal sticks, etc.).
4Poor acceleration (fails to accelerate, engine stalls, etc.).
5Vibration, abnormal noise (operating noise is loud, noise is produced during operation from the front of vehicle (right, left)
(tones:), noise is produced during operation from the rear of vehicle (tones:, others)
6Other phenomena (concrete symptoms)
3. CONDITIONS UNDER WHICH TROUBLE OCCURS
Environment1Weather (fine, cloudy, rain, snow, etc.)
2Ambient temperature (°C/°F)
3Road (urban area, suburbs, highway, general road, ascending slope, descending slope, paved road, gravel road, muddy
road, sandy place, etc.)
4Road surface (dry, wet, new-fallen snow, compressed snow, frozen slope, etc.)
Conditions
1Brakes (decelerationg, continuous/intermittent)2Accelerator (accelerationg, continuous/intermittent)
3Travel speed (miles, advancing, accelerating, reducing speed, low speed, turning, etc.)
4Condition of tire of each wheel (air pressure, degree of wear, whether or not genuine parts are used, whether
or not chain is passed around tires, whether or not T tire is used.) others ()
5Condition of suspension alignment ()
6Loading state ()
4. REPAIRED PARTS ARE USED OR NOT
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6. Diagnostics Chart for On-board Diagnosis System

C: INSPECTION MODE
The on-board diagnosis system is designed to detect prob-
lems while the vehicle is being driven. If a problem is found,
the ABS and TCS warning light will illuminate to inform the
driver of the occurrence of a problem. When the warning
light is on, the ABS/TCS system will be inactive and the
normal braking function will work. It is possible for the most
recent trouble code and history of problem to be stored in
memory until cleared.
B4M0082C
D: TROUBLE CODES
When on-board diagnosis of the ABS/TCS control module
detects a problem, the information will be stored in the EEP
ROM as a trouble code. (Stored codes will stay in memory
until they are cleared.)
1. CALLING UP A TROUBLE CODE
1) Take out diagnosis connector from side of driver’s seat
heater unit.
2) Turn ignition switch OFF.
3) Connect diagnosis connector terminal No. 4 to diagno-
sis terminal.
4) Turn ignition switch ON.
5) TCS warning light is set in the diagnostic mode and
blinks to identify trouble code.
6) After the start code (11) is shown, the trouble codes will
be shown in order of the last information first.
NOTE:
When there are no trouble codes in memory, only the start
code (11) is shown.
B4M0383A
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6. Diagnostics Chart for On-board Diagnosis System

B4M0082C
2. CLEARING MEMORY
1) After calling up a trouble code, disconnect ABS check
connector terminal No. 4 from diagnosis terminal.
2) Repeat 3 times within approx. 12 seconds; connecting
and disconnecting terminal No. 4 and diagnosis terminal
for at least 0.15 seconds each time.
3) Turn off the ignition key.
B4M0384A
NOTE:
After diagnostics is completed, make sure to clear memory.
Make sure only start code (11) is shown after memory is
cleared.
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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

B4M0715A
1. CHECK TCS WARNING LIGHT.
1) Turn ignition switch OFF.
2) Disconnect all connectors from ABS/TCS control mod-
ule.
3) Turn ignition switch ON.
4) Measure voltage between ABS/TCS control module
connector and body.
Connector & terminal / Specified voltage:
(P6) No. 3 — body / 10 — 14 V
B4M0387A
2. CHECK DIAGNOSIS TERMINAL.
1) Turn ignition switch OFF.
2) Measure resistance between diagnosis terminal and
body.
Connector/Specified resistance:
B81 — body / 0Ω
B4M0388A
3. CHECK DIAGNOSIS CONNECTOR.
1) Turn ignition switch OFF.
2) Disconnect all connectors from ABS/TCS control mod-
ule.
3) Measure resistance between diagnosis connector and
body.
Connector & terminal / Specified resistance:
(B82) No. 4 — body / 0Ω
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7. Diagnostics Chart for Warning Light Circuit Failure