SUBARU LEGACY 1997 Service Repair Manual

N: DIAGNOSTICS PROCEDURE FOR
HEADLIGHT ALARM SIGNAL
1. Check headlight alarm output signal for security
control module.
Not OK
OK
5. Check headlight alarm relay.
OK Not OK
Repair or replace
wiring harness of
headlight circuit.
Replace headlight
alarm relay.
2. Check power supply for headlight alarm relay.
OK
Not OK
Repair or replace wiring harness between
headlight alarm relay and battery.
3. Check continuity of headlight alarm relay.
OK
Not OK
Replace headlight alarm relay.
4. Check harness connector between headlight
alarm relay and security control module.
OK
Not OK
Repair or replace wiring harness between
headlight alarm relay and security control
module.
Replace security control module.
B6M0457A
1. CHECK HEADLIGHT ALARM OUTPUT SIGNAL
FOR SECURITY CONTROL MODULE.
1) Remove security control module without disconnecting
connector.
2) Measure voltage between security control module con-
nector and body.
Connector & terminal / Specified voltage:
(B93) No. 12—Body / 10 V, or more
3) Set security system in armed state.
4) Open the door without ignition key to operate the secu-
rity system (alarm state).
5) Measure voltage between security control module and
body during alarm state.
Connector & terminal / Specified voltage:
(B93) No. 12—Body / repeats 1 V, max. (0.2 sec.)
and 10 V, or more (0.6 sec.)
intervals





106
6-2DIAGNOSTICS
6. Security System

B6M0508A
2. CHECK POWER SUPPLY FOR HEADLIGHT ALARM
RELAY.
1) Remove headlight alarm relay without disconnecting
connector.
2) Measure voltage between headlight alarm relay con-
nector and body.
Connector & terminal / Specified voltage:
(B58) No. 1—Body / 10 V, or more
B6M0455A
3. CHECK CONTINUITY OF HEADLIGHT ALARM
RELAY.
1) Remove headlight alarm relay.
2) Check continuity between terminals No. 1 and No. 2 of
headlight alarm relay.
B6M0502A
4. CHECK HARNESS CONNECTOR BETWEEN
HEADLIGHT ALARM RELAY AND SECURITY
CONTROL MODULE.
1) Disconnect connectors of headlight alarm relay and
security control module.
2) Measure resistance of harness connector between
headlight alarm relay and security control module.
Connector & terminal / Specified resistance:
(B58) No. 2—(B93) No. 12 / 10Ω, max.
5. CHECK HEADLIGHT ALARM RELAY.
Refer to 6-2 [W22B2] for inspection of headlight alarm
relay.
107
6-2DIAGNOSTICS
6. Security System

1. General
1. GENERAL DESCRIPTION

The on-board diagnostics (OBD) system detects and
indicates a fault in various inputs and outputs of the com-
plex electronic control. CHECK ENGINE malfunction indi-
cator lamp (MIL) in the combination meter indicates occur-
rence of a fault or trouble.

Further, against such a failure or sensors as may disable
the drive, the fail-safe function is provided to ensure the
minimal driveability.

The OBD system incorporated with the vehicles within
this engine family complies with Section 1968.1, California
Code of Regulations (OBD-II regulation). The OBD system
monitors the components and the system malfunction
listed in Engine Section which affects on emissions.

When the system decides that a malfunction occurs, MIL
illuminates. At the same time of the MIL illumination or
blinking, a diagnostic trouble code (DTC) and a freeze
frame engine conditions are stored into on-board com-
puter.

The OBD system stores freeze frame engine condition
data (engine load, engine coolant temperature, fuel trim,
engine speed and vehicle speed, etc.) into on-board com-
puter when it detects a malfunction first.

If the OBD system detects the various malfunctions
including the fault of fuel trim or misfire, the OBD system
first stores freeze frame engine conditions about the fuel
trim or misfire.

When the malfunction does not occur again for three
consecutive driving cycles, MIL is turned off, but DTC
remains at on-board computer.

The OBD-II system is capable of communication with a
general scan tool (OBD-II general scan tool) formed by ISO
9141 CARB.

The OBD-II diagnostics procedure is different from the
usual diagnostics procedure. When troubleshooting OBD-II
vehicles, connect Subaru select monitor or the OBD-II gen-
eral scan tool to the vehicle.
A: ENGINE
1. ENGINE AND EMISSION CONTROL SYSTEM

The Multipoint Fuel Injection (MFI) system is a system
that supplies the optimum air-fuel mixture to the engine for
all the various operating conditions through the use of the
latest electronic technology.
With this system fuel, which is pressurized at a constant
pressure, is injected into the intake air passage of the cyl-
inder head. The injection quantity of fuel is controlled by an
intermittent injection system where the electro-magnetic
injection valve (fuel injector) opens only for a short period
of time, depending on the quantity of air required for one
cycle of operation. In actual operation, the injection quan-
2
2-7ON-BOARD DIAGNOSTICS II SYSTEM
1. General

tity is determined by the duration of an electric pulse
applied to the fuel injector and this permits simple, yet
highly precise metering of the fuel.

Further, all the operating conditions of the engine are
converted into electric signals, and this results in additional
features of the system, such as large improved
adaptability, easier addition of compensating element, etc.
The MFI system also has the following features:
1) Reduced emission of harmful exhaust gases.
2) Reduced in fuel consumption.
3) Increased engine output.
4) Superior acceleration and deceleration.
5) Superior startability and warm-up performance in cold
weather since compensation is made for coolant and
intake air temperature.
3
2-7ON-BOARD DIAGNOSTICS II SYSTEM
1. General

2. SCHEMATIC (2200 cc FWD AND TAIWAN SPEC.
VEHICLES)
B2M0709A
4
2-7ON-BOARD DIAGNOSTICS II SYSTEM
1. General

1Engine control module (ECM)

2Ignition coil

3Ignitor

4Crankshaft position sensor

5Camshaft position sensor

6Throttle position sensor

7Fuel injectors

8Pressure regulator

9Engine coolant temperature sensor

10Mass air flow sensor

11Idle air control solenoid valve

12Purge control solenoid valve

13Fuel pump

14PCV valve

15Air cleaner

16Canister

17Main relay

18Fuel pump relay

19Fuel filter

20Front catalytic converter

21Rear catalytic converter

22EGR valve (AT vehicles only)

23EGR control solenoid valve (AT vehicles only)

24Radiator fan
25Radiator fan relay

26Pressure sources switching solenoid valve

27Knock sensor

28Back-pressure transducer (AT vehicles only)

29Front oxygen sensor

30Rear oxygen sensor (2200 cc Federal spec. vehicles)

31Pressure sensor

32A/C compressor

33Inhibitor switch

34CHECK ENGINE malfunction indicator lamp (MIL)

35Tachometer

36A/C relay

37A/C control module

38Ignition switch

39Transmission control module (TCM) (AT vehicles only)

40ABS/TCS control module (TCS equipped models)

41Vehicle speed sensor

42Data link connector (For Subaru select monitor)

43Data link connector (For Subaru select monitor and OBD-II
general scan tool)

44Two way valve

45Rear oxygen sensor (2200 cc California spec. vehicles)

46Filter
5
2-7ON-BOARD DIAGNOSTICS II SYSTEM
1. General

3. SCHEMATIC (2200 cc AWD EXCEPT TAIWAN
SPEC. VEHICLES)
B2M0914A
6
2-7ON-BOARD DIAGNOSTICS II SYSTEM
1. General

1Engine control module (ECM)

2Ignition coil

3Ignitor

4Crankshaft position sensor

5Camshaft position sensor

6Throttle position sensor

7Fuel injectors

8Pressure regulator

9Engine coolant temperature sensor

10Mass air flow sensor

11Idle air control solenoid valve

12Purge control solenoid valve

13Fuel pump

14PCV valve

15Air cleaner

16Canister

17Main relay

18Fuel pump relay

19Fuel filter

20Front catalytic converter

21Rear catalytic converter

22EGR valve (AT vehicles only)

23EGR control solenoid valve (AT vehicles only)

24Radiator fan

25Radiator fan relay

26Pressure sources switching solenoid valve
27Front oxygen sensor

28Rear oxygen sensor (2200 cc Federal spec. vehicles)

29Pressure sensor

30A/C compressor (With A/C models)

31Inhibitor switch

32CHECK ENGINE malfunction indicator lamp (MIL)

33Tachometer

34A/C relay (With A/C models)

35A/C control module (With A/C models)

36Ignition switch

37Transmission control module (TCM)

38Vehicle speed sensor

39Data link connector (For Subaru select monitor)

40Data link connector (For Subaru select monitor and OBD-II
general scan tool)

41Rear oxygen sensor (2200 cc California spec. vehicles)

42Knock sensor

43Back-pressure transducer (AT vehicles only)

44Filter

45Fuel tank pressure sensor

46Pressure control solenoid valve

47Fuel temperature sensor

48Fuel level sensor

49Vent control solenoid valve

50Air filter
7
2-7ON-BOARD DIAGNOSTICS II SYSTEM
1. General

4. SCHEMATIC (2500 cc MODEL)
B2M0710A
8
2-7ON-BOARD DIAGNOSTICS II SYSTEM
1. General

1Engine control module (ECM)

2Ignition coil

3Ignitor

4Crankshaft position sensor

5Camshaft position sensor

6Throttle position sensor

7Fuel injectors

8Pressure regulator

9Engine coolant temperature sensor

10Mass air flow sensor

11Idle air control solenoid valve

12Purge control solenoid valve

13Fuel pump

14PCV valve

15Air cleaner

16Canister

17Main relay

18Fuel pump relay

19Fuel filter

20Front catalytic converter

21Rear catalytic converter

22EGR valve
23EGR control solenoid valve

24Radiator fan

25Radiator fan relay

26Pressure sources switching solenoid valve

27Knock sensor

28Back-pressure transducer

29Front oxygen sensor

30Rear oxygen sensor

31Pressure sensor

32A/C compressor

33Inhibitor switch

34CHECK ENGINE malfunction indicator lamp (MIL)

35Tachometer

36A/C relay

37A/C control module

38Ignition switch

39Transmission control module (TCM)

40Vehicle speed sensor

41Data link connector (Subaru select monitor)

42Data link connector (OBD-II general scan tool)

43Two way valve

44Filter
9
2-7ON-BOARD DIAGNOSTICS II SYSTEM
1. General