power supply circuit SUBARU LEGACY 1995 Service Service Manual

1.Check transmission type.
AT
MT
Check AT/MT identification circuit.
2.Check output signal from ECM.

3.Check harness connector.
4.Check harness connector.
5.Check pressure sources switching solenoid
valve.
6.Check power supply to pressure sources
switching solenoid valve.
CAUTION:
After repair or replacement of faulty parts, conduct
CLEAR MEMORY and INSPECTION MODE. [T3D0] and [T3E0].>
WIRING DIAGRAM:

LHD model
OBD0156




320
2-7ON-BOARD DIAGNOSTICS II SYSTEM
11. Diagnostics Chart with Trouble Code

OBD0676A
6CHECK POWER SUPPLY TO PRESSURE
SOURCES SWITCHING SOLENOID VALVE.
1) Turn ignition switch to ON.
2) Measure voltage between pressure sources switching
solenoid valve harness connector and body.
: Connector & terminal
(B1) No. 2—Body / 10 V, or more
: Confirm good connection at pressure sources
switching solenoid valve connector.
: Repair open circuit of harness between main relay
connector and pressure sources switching sole-
noid valve connector.
324
2-7ON-BOARD DIAGNOSTICS II SYSTEM
11. Diagnostics Chart with Trouble Code

OBD0736A
1
CHECK OUTPUT SIGNAL FROM ECM.
1) Turn ignition switch to OFF.
2) Connect test mode connector at the lower portion of
instrument panel (on the driver’s side), to the side of the
center console box.
3) Turn ignition switch to ON.
OBD0674A
4) Measure voltage between ECM and body.
: Connector & terminal
(B84) No. 77—Body/10 V, or more and 1 V
or less at every 2 seconds
: Go to step 6.
: Go to next.
OBD0534A
: Connector & terminal
(B84) No. 88—Body/10 V, or more
: Go to step 5.
: Go to step 2.
2
CHECK POWER SUPPLY FOR RELAYS.
Turn ignition switch to OFF.
: Is the fuse in power supply circuit broken?
: Replace the fuse.
: Go to step 3.
OBD0535
3CHECK MAIN FAN RELAY 1, SUB FAN RELAY
1 AND MAIN FAN RELAY.
1) Remove main fan relay 1. (With A/C models only)
2) Measure resistance between main fan relay 1 termi-
nals.
: Terminal
No. 1—No. 3/97±10Ω
: Go to next step.
: Replace main fan relay 1.
334
2-7ON-BOARD DIAGNOSTICS II SYSTEM
11. Diagnostics Chart with Trouble Code

1.Check harness connector between TCM and
throttle position sensor.
2.Check throttle position sensor.
3.Check input signal for TCM.
4.Check power supply to throttle position
sensor.
CAUTION:
After repair or replacement of faulty parts, conduct
CLEAR MEMORY and INSPECTION MODES. [T3D0] and [T3E0].>
WIRING DIAGRAM:
OBD0502
NOTE:
For the diagnostic procedure on throttle position sensor
circuit, refer to“3-2 [T7L0]”.



342
2-7ON-BOARD DIAGNOSTICS II SYSTEM
11. Diagnostics Chart with Trouble Code

L: TROUBLE CODE 31
—THROTTLE POSITION SENSOR—
DIAGNOSIS:
Input signal circuit of throttle position sensor is open or
shorted.
TROUBLE SYMPTOM:
Shift point too high or too low; engine brake not effected in
“3”range; excessive shift shock; excessive tight corner
“braking”
1. Check harness connector between TCM and
throttle position sensor.
OK
Not OK
Repair or replace harness connectors.
2. Check throttle position sensor.
OK
Not OK
Replace throttle position sensor.
3. Check input signal for TCM.
Not OK
OK

Repair TCM connector terminal poor contact.

Replace TCM.
4. Check power supply to throttle position
sensor.
OK
Not OK
Repair or replace harness connectors.

Repair TCM connector terminal poor contact.

Replace TCM.
OBD0502




42
3-2AUTOMATIC TRANSMISSION AND DIFFERENTIAL
7. Diagnostic Chart with Trouble Code

1. Supplemental Restraint System
“Airbag”
Airbag system wiring harness is routed near the A.B.S.
control module, A.B.S. sensor and hydraulic control unit.
CAUTION:

All Airbag system wiring harness and connectors
are colored yellow. Do not use electrical test equip-
ment on these circuit.

Be careful not to damage Airbag system wiring har-
ness when servicing the A.B.S. control module, A.B.S.
sensor and hydraulic control unit.
2. Pre-inspection
Before performing diagnostics, check the following items
which might affect A.B.S. problems:
1. POWER SUPPLY
1) Measure battery voltage and specific gravity of electro-
lyte.
Standard voltage: 12 V, or more
Specific gravity: Above 1.260
2) Check the condition of the main and other fuses, and
harnesses and connectors. Also check for proper ground-
ing.
2. BRAKE FLUID
1) Check brake fluid level.
2) Check brake fluid leakage.
3. BRAKE DRAG
Check brake drag.
4. BRAKE PAD AND ROTOR
Check brake pad and rotor.
5. TIRE SPECIFICATIONS, TIRE WEAR AND AIR
PRESSURE
Check tire specifications, tire wear and air pressure. to 4-2 [S1A0].>
2
4-4aBRAKES
1. Supplemental Restraint System“Airbag”- 2. Pre-inspection

1. Supplemental Restraint System
“Airbag”
Airbag system wiring harness is routed near the A.B.S.
control module, A.B.S. sensor and hydraulic control unit.
CAUTION:

All Airbag system wiring harness and connectors
are colored yellow. Do not use electrical test equip-
ment on these circuit.

Be careful not to damage Airbag system wiring har-
ness when servicing the A.B.S. control module, A.B.S.
sensor and hydraulic control unit.
2. Pre-inspection
Before performing diagnostics, check the following items
which might affect A.B.S. problems:
1. POWER SUPPLY
1) Measure battery voltage and specific gravity of electro-
lyte.
Standard voltage: 12 V, or more
Specific gravity: Above 1.260
2) Check the condition of the main and other fuses, and
harnesses and connectors. Also check for proper ground-
ing.
2. BRAKE FLUID
1) Check brake fluid level.
2) Check brake fluid leakage.
3. BRAKE DRAG
Check brake drag.
4. BRAKE PAD AND ROTOR
Check brake pad and rotor.
5. TIRE SPECIFICATIONS, TIRE WEAR AND AIR
PRESSURE
Check tire specifications, tire wear and air pressure. to 4-2 [S1A0].>
2
4-4aBRAKES
1. Supplemental Restraint System“Airbag”- 2. Pre-inspection

A: TROUBLE CODE (NONE: A)
—TROUBLE IN WARNING LIGHT DRIVE
CIRCUIT—
DIAGNOSIS:

Faulty A.B.S. warning light

Faulty harness connector

Faulty A.B.S. control module

Faulty valve relay
TROUBLE SYMPTOM:

Warning light does not illuminate.

Impossible to read trouble code.
NOTE:
When ignition key is on, warning light should turn off after
1.5 seconds if system is normal.
1. Check A.B.S. warning light power supply.
OK
Not OK
Repair A.B.S. warning light power line.
2. Check input voltage of A.B.S. control module
and hydraulic control unit from A.B.S. warn-
ing light.
OK
Not OK
Repair harness/connector.
3. Check ground line of A.B.S. control module
and hydraulic control unit.
OK
Not OK
Repair ground line.
4. Check valve relay.
OK
Not OK
Replace valve relay.
Replace A.B.S. control module and hydraulic control
unit.




11
4-4aBRAKES
7. Diagnostics Chart with Trouble Code

B: TROUBLE CODE (NONE: B)
—TROUBLE IN WARNING LIGHT DRIVE
CIRCUIT—
DIAGNOSIS:

Faulty harness

Faulty A.B.S. control module
TROUBLE SYMPTOM:

Warning light remains on.

Impossible to read trouble code.
Check trouble code while the hydraulic control unit
valve relay is removed.
Not OK
OK
Perform diagnostics in accordance with trouble
code.
Make sure warning light is off when the valve relay
and A.B.S. control module is removed.
OK
Not OK
Harness is shorted to body.
Repair harness/connector.
1. Check input voltage to A.B.S. control module
from A.B.S. warning light.
OK
Not OK
Repair harness/connector.
2. Check power supply to A.B.S. control module.
OK
Not OK
Repair harness/connector.
3. Check A.B.S. control module ground line.
OK
Not OK
Repair harness/connector.
Replace A.B.S. control module.





14
4-4aBRAKES
7. Diagnostics Chart with Trouble Code

I: TROUBLE CODE 51
—FAULTY VALVE RELAY—
DIAGNOSIS:

Faulty valve relay

Faulty harness

Faulty A.B.S. control module
TROUBLE SYMPTOM:

A.B.S. does not operate.
1. Check power supply circuit of A.B.S. control
module.
OK
Not OK
Repair harness/connector.
2. Check output voltage to A.B.S. control
module.
OK
Not OK
Replace A.B.S. control module.
3. Check input voltage of A.B.S. control module.
Not OK
OK
Replace A.B.S. control module.
4. Check harness connector between A.B.S.
control module and hydraulic control unit.
OK
Not OK
Repair harness/connector.
5. Check power supply circuit of hydraulic
control unit.Not OK
Repair harness/connector.
6. Check valve relay.Replace valve relay.
Replace hydraulic control unit.






37
4-4aBRAKES
7. Diagnostics Chart with Trouble Code