engine SUBARU LEGACY 1997 Service Repair Manual

4. Diagnostics Chart for On-board
Diagnostic System
A: BASIC DIAGNOSTICS PROCEDURE
1) Airbag warning light comes “ON”.
2) Turn ignition switch to “ON”, (engine “OFF”) and observe airbag warning light.
3) If airbag warning light stays “ON” after about 7 seconds or remains “OFF”, or comes back “ON” after 30 seconds, this indicates a
current problem. Proceed to step 8).
If airbag warning light comes “ON” for about 7 seconds, then goes out and stays out, this indicates normal system operation at this
time. Check the memory for intermittent problems by performing the procedure outlined in 5-5b [T4B0] “ON-BOARD DIAGNOSTICS”.
Proceed to step 4).
4) If trouble code indicated, proceed to step 5).
If normal code indicated, proceed to step 6).
5) Repair and replacement, proceed to step 7).
6) Repair and replacement, proceed to step 7).
7) Turn ignition switch “ON”, (engine “OFF”) and observe airbag warning light. If airbag warning light stays “ON” after about 7 seconds
or comes back “ON” after 30 seconds, proceed to step 8).
If airbag warning light comes “ON” for about 7 seconds, then goes out and stays out, proceed to step 9).
8) Repair and replacement. Proceed to step 10).
9) Clear memory. Proceed to step 10).
10) END
B5M0115B
B: ON-BOARD DIAGNOSTIC
When the airbag system is in functioning condition, the
airbag warning light will remain on for about 7 seconds and
go out when the ignition switch is set to ON.
If there is any malfunction, the airbag warning light will
either stay on or off continuously. In such cases, perform
on-board diagnostic in accordance with the specified pro-
cedure to determine trouble codes.
1) Turn ignition switch ON (with engine OFF).
2) Connect DIAG. terminal

1to No. 1 terminal of diagno-
sis connector

2located below lower cover.
3) Check in accordance with the trouble code indicated by
the AIRBAG warning light, and record the trouble codes.
4) Turn the ignition switch “OFF” and remove the DIAG.
terminal from No.1 terminal of diagnosis connector.
9
5-5bSUPPLEMENTAL RESTRAINT SYSTEM (ELECTRIC SENSOR TYPE)
4. Diagnostics Chart for On-board Diagnostic System

B5M0116B
C: CLEAR MEMORY
After eliminating problem as per trouble code, clear
memory as follows:
Make sure ignition switch is ON (and engine off). Connect
one DIAG. terminal

1on diagnosis connector
2terminal
No. 1.
While warning light is flashing, connect the other DIAG.
terminal

3on terminal No. 2 for at least three seconds.
After memory is cleared, normal warning light flashing rate
resumes. (Warning light flashes every 0.6 seconds ON-
OFF operation.) Memory cannot be cleared if any problem
exists.
After clear memory and then DIAG. terminals

1and
3,
extract from diagnosis connector

2.
10
5-5bSUPPLEMENTAL RESTRAINT SYSTEM (ELECTRIC SENSOR TYPE)
4. Diagnostics Chart for On-board Diagnostic System

B: TROUBLE CODE 11
DIAGNOSIS:
Airbag control module is faulty.
Airbag main harness circuit is open.
Fuse No. 8 is blown.
Body harness circuit is open.
1. Airbag control module inspection
2. Airbag main harness inspection
3. Fuse No. 8 inspection
CAUTION:
Before performing diagnostics on airbag system, turn
ignition switch“OFF”, disconnect battery ground
cable and then wait at least 20 seconds.
After 20 seconds elapse, remove instrument panel
lower cover, and disconnect (AB3) and (AB8), (AB9)
and (AB10).
G5M0559
1. AIRBAG CONTROL MODULE INSPECTION
1) Disconnect connector (AB6) from airbag control module
and connect it to test harness B2
connector (8B).
2) Connect battery ground cable and turn ignition switch
“ON”. (engine off)
3) Measure voltage across connector (5B) terminal and
chassis ground.
: Connector & terminal
(5B) No. 2 (+)—Chassis ground ():
Is voltage more than 10 V?
: Replace airbag control module.
: Go to step2.


17
5-5bSUPPLEMENTAL RESTRAINT SYSTEM (ELECTRIC SENSOR TYPE)
5. Diagnostics Chart with Trouble Code

H: TROUBLE CODE 31
DIAGNOSIS:
Airbag control module is faulty.
Airbag main harness circuit is open.
Fuse No. 16 is blown.
Body harness circuit is open.
1. Airbag control module inspection
2. Airbag main harness inspection
3. Fuse No. 16 inspection
CAUTION:
Before performing diagnostics on airbag system, turn
ignition switch“OFF”, disconnect battery ground
cable and then wait at least 20 seconds.
After 20 seconds elapse, remove instrument panel
lower cover, and disconnect (AB3) and (AB8), (AB9)
and (AB10).
G5M0559
1. AIRBAG CONTROL MODULE INSPECTION
1) Disconnect connector (AB6) from airbag control module
, and connect it to test harness B2
connector (8B).
2) Connect battery ground cable and turn ignition switch
“ON”(engine off).
3) Measure voltage across connector (5B) terminal and
chassis ground.
: Connector & terminal
(5B) No. 5 (+)—Chassis ground ():
Is voltage more than 10 V?
: Replace airbag control module.
: Go to step2.


26
5-5bSUPPLEMENTAL RESTRAINT SYSTEM (ELECTRIC SENSOR TYPE)
5. Diagnostics Chart with Trouble Code

J: TROUBLE CODE 34
DIAGNOSIS:
Airbag main harness circuit (Passenger) is shorted to
power supply.
Airbag module harness (Passenger) is shorted to power
supply.
Airbag control module is faulty.
1. Airbag main harness inspection
CAUTION:
Before performing diagnostics on airbag system, turn
ignition switch“OFF”, disconnect battery ground ter-
minal and then wait at least 20 seconds.
After 20 seconds elapse, remove instrument panel
lower cover, and disconnect (AB3) and (AB8), (AB9)
and (AB10).
G5M0559
1. AIRBAG MAIN HARNESS INSPECTION
1) Disconnect connector (AB6) from airbag control module
, and connect it to test harness B2
connector (8B).
2) Connect battery ground cable and turn ignition switch
“ON”(engine off).
3) Measure voltage across each test harness B2 connec-
tor (5B) terminal and chassis ground.
: Connector & terminal
(5B) No. 6 (+)—Chassis ground ():
Is voltage less than 1 V?
: Go to next.
: Replace airbag main harness.
: Connector & terminal
(5B) No. 7 (+)—Chassis ground ():
Is voltage less than 1 V?
: Replace airbag control module.
: Replace airbag main harness.
29
5-5bSUPPLEMENTAL RESTRAINT SYSTEM (ELECTRIC SENSOR TYPE)
5. Diagnostics Chart with Trouble Code

M: TROUBLE CODE 43
DIAGNOSIS:
Airbag main harness circuit (Driver) is shorted to power
supply.
Airbag module harness (Driver) is shorted to power sup-
ply.
Roll connector is shorted to power supply.
Airbag control module is faulty.
1. Airbag main harness inspection
CAUTION:
Before performing diagnostics on airbag system, turn
ignition switch“OFF”, disconnect battery ground ter-
minal and then wait at least 20 seconds.
After 20 seconds elapse, remove instrument panel
lower cover, and disconnect (AB3) and (AB8), (AB9)
and (AB10).
G5M0559
1. AIRBAG MAIN HARNESS INSPECTION
1) Disconnect connector (AB6) from airbag control module
, and connect it to test harness B2
connector (8B).
2) Connect battery ground cable and turn ignition switch
“ON”(engine off).
3) Measure voltage across each test harness B2 connec-
tor (5B) terminal and chassis ground.
: Connector & terminal
(5B) No. 1 (+)—Chassis ground ():
Is voltage less than 1 V?
: Go to next.
: Replace airbag main harness.
: Connector & terminal
(5B) No. 14 (+)—Chassis ground ():
Is voltage less than 1 V?
: Replace airbag control module.
: Replace airbag main harness.
32
5-5bSUPPLEMENTAL RESTRAINT SYSTEM (ELECTRIC SENSOR TYPE)
5. Diagnostics Chart with Trouble Code

B5M0123B
2. INSPECTION OF BODY HARNESS, CONNECTOR
AND AIRBAG WARNING LIGHT
1) Turn ignition switch“OFF”and connect body harness
connector (B31) to test connector A connector (1A).
G5M0455
2) Connect battery ground cable and turn ignition switch
“ON”, (engine off) and connect connectors (3A) and (4A).
: Does the airbag warning light come off?
: Go to step 3).
: Go to next.
B5M0124A
: Is there anything unusual to body harness?
: Repair body harness.
: Replace airbag warning light module
1.
NOTE:
After problem has been eliminated, disconnect connectors
(3A) and (4A).
G5M0559
3) Turn ignition switch“OFF”, disconnect battery ground
cable and then wait at least 20 seconds, and re-connect
connectors (AB1) and (B31).
4) Remove instrument panel lower cover and disconnect
(AB3) with (AB8), then disconnect connector (AB6) from
airbag control module, and connect
it to test harness B2 connector (8B).
G5M0458
5) Connect battery ground cable and turn ignition switch
“ON,”(engine off) and connect connectors (6B) and (7B).
: Does the airbag warning light come on?
: Go to step3.
: Replace airbag main harness.
NOTE:
After problem has been eliminated, disconnect connectors
(6B) and (7B).
34
5-5bSUPPLEMENTAL RESTRAINT SYSTEM (ELECTRIC SENSOR TYPE)
5. Diagnostics Chart with Trouble Code

O: AIRBAG WARNING LIGHT REMAINS OFF.
DIAGNOSIS:
Fuse No. 15 is blown.
Body harness circuit is open.
Airbag warning light is faulty.
Airbag main harness is faulty.
Airbag control module is faulty.
1. Fuse No. 15 inspection
2. Body harness inspection
3. Airbag warning light module (in combination
meter) inspection
4. Airbag main harness inspection
CAUTION:
Before performing diagnostics on airbag system, turn
ignition switch“OFF”, disconnect battery ground
terminal, and then wait at least 20 seconds.
G5M0460
1. FUSE No. 15 INSPECTION
Remove and visually check fuse No. 15.
: Is fuse No. 15 blown?
: Replace fuse No. 15.
If fuse No. 15 blows again, go to step2.
: Go to step2.
2. BODY HARNESS INSPECTION
Turn ignition switch“ON”(engine off) to make sure other
warning lights (in combination meter) illuminate.
: Do all the warning lights (in combination
meter) except airbag warning light come
on?
: Go to step3.
: Repair body harness.



36
5-5bSUPPLEMENTAL RESTRAINT SYSTEM (ELECTRIC SENSOR TYPE)
5. Diagnostics Chart with Trouble Code

B5M0122B
3. AIRBAG WARNING LIGHT MODULE (IN
COMBINATION METER) INSPECTION
1) Turn ignition switch“OFF”, disconnect battery ground
cable and then wait at least 20 seconds.
2) Disconnect body harness connector (B31) from connec-
tor (AB1).
B5M0124A
3) Connect battery ground cable and turn ignition switch
“ON”(engine off) to make sure airbag warning light illumi-
nates.
: Does the airbag warning light come on?
: Go to step4.
: Replace airbag warning light module
1.
G5M0312
4. AIRBAG MAIN HARNESS INSPECTION
1) Turn ignition switch“OFF”, disconnect battery ground
cable and then wait at least 20 seconds.
2) Connect body harness connector (B31) and connector
(AB1).
3) Disconnect connectors (AB3) and (AB8) below steering
column.
G5M0313
4) Disconnect connector (AB6) from airbag control mod-
ule.
5) Connect battery ground cable and turn ignition switch
“ON”to make sure airbag warning light illuminates.
: Does the airbag warning light come on?
: Replace airbag control module.
: Replace airbag main harness.
37
5-5bSUPPLEMENTAL RESTRAINT SYSTEM (ELECTRIC SENSOR TYPE)
5. Diagnostics Chart with Trouble Code

5. FUSE No. 16, AIRBAG MAIN HARNESS, BODY
HARNESS VIBRATION INSPECTION
Conduct vibration inspection on fuse No. 16, airbag main
harness and body harness.
CAUTION:
Do not shake or vibrate airbag control module.
: Do fuse No. 16, airbag main harness or body
harness malfunction again when shaking?
: Replace faulty airbag component parts.
: Go to step6.
NOTE:
Gently shake each part.
G5M0461
6. SHOWERING INSPECTION TO BODY
Spray water on vehicle body.
CAUTION:
Do not directly spray water on each part.
: Does water leak into the passenger com-
partment when showering vehicle?
: Replace faulty airbag component parts.
: Go to step7.
NOTE:
If leaks are noted, check wiring harnesses as water may
leak along them and get parts wet.
7. WARNING LIGHT ILLUMINATION CHECK
Turn ignition switch“ON”(engine off) and observe airbag
warning light.
: Does the airbag warning light comes on for
about 7 seconds, then go out and stay out?
: Clear memory.
:Goto“DIAGNOSTICS PROCEDURE”.

43
5-5bSUPPLEMENTAL RESTRAINT SYSTEM (ELECTRIC SENSOR TYPE)
5. Diagnostics Chart with Trouble Code