Page 1769 of 2890
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.
105
6-2DIAGNOSTICS
6. Security System
Page 1770 of 2890

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 trips, 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
Page 1771 of 2890
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
Page 1772 of 2890
2. SCHEMATIC (2200 cc FWD AND TAIWAN MODELS)
B2M0709A
4
2-7ON-BOARD DIAGNOSTICS II SYSTEM
1. General
Page 1773 of 2890

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 (Except 2200 cc California model)
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 model only)
46Filter
5
2-7ON-BOARD DIAGNOSTICS II SYSTEM
1. General
Page 1774 of 2890
3. SCHEMATIC (2200 cc AWD EXCEPT TAIWAN
MODEL)
B2M0914A
6
2-7ON-BOARD DIAGNOSTICS II SYSTEM
1. General
Page 1775 of 2890

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 (Except 2200 cc California model)
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 model)
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
Page 1776 of 2890
4. SCHEMATIC (2500 cc MODEL)
B2M0710A
8
2-7ON-BOARD DIAGNOSTICS II SYSTEM
1. General