1999 MITSUBISHI LANCER EVOLUTION VI Workshop Manual

SRS – Troubleshooting52B-9
Code No.24, 25, 64 or 65 Front passenger’s side air bag
module (squib) systemProbable cause
These diagnosis codes are output if there is abnormal resistance between the input
terminals of the driver’s side air bag module (squib).
The trouble causes for each diagnosis code No. are as follows.
Malfunction of wiring harnesses or connectors

Malfunction of front passenger’s side air bag module
(squib)

Malfunction of SRS-ECU
Code No.Trouble symptom
24
Short in front passenger’s side air bag module (squib) or harness short

Malfunction of connector*
25
Open circuit in front passenger’s side air bag module (squib) or open harness

Malfunction of connector contact
64
Short in front passenger’s side air bag module (squib) harness leading to the power
supply
65
Short in front passenger’s side air bag module (squib) harness leading to the earth
NOTE
*: The connector in the squib circuit has a built-in short bar which short-circuits between plus (+) lead and minus
(–) lead of the squib circuit when the connector is not being connected to prevent an accidental air bag deployment
possibly caused by static electricity, etc. Therefore, malfunction of the connector can also be caused by this
short bar which fails to be released even when the connector is reconnected if it is damaged.
OK
Check trouble symptoms.
NG
Check the harness wire
between the front passen-
ger’s side air bag module
(squib) and SRS-ECU.NG
Repair
OK
Replace the SRS-ECU.
Ye sCheck the following
connectors:
B-01, B-51NG
RepairSRS check harness
(MB991613)
Body
wiring
harness
1
No
Replace the front passenger’s side air bag module.MUT-II Self-diag code

Disconnect front
passenger’s side air bag
module connector B-01.

Connect SRS check
harness connector (1).

Erase diagnosis code
memory.
Are code Nos.24, 25, 64 or 65
output?
Code No.31 or 32 SRS-ECU capacitor systemProbable cause
Probable cause
These diagnosis codes are output if there is abnormal resistance between the input
terminals of the driver’s side air bag module (squib).
Malfunction of SRS-ECU
Code No.Trouble symptom
31
Voltage at the capacitor terminal is higher than the specified value for five seconds
or more
32
Voltage at the capacitor terminal is lower than the specified value for five seconds
or more (this is not detected if diagnosis code No.41 or 42 indicating system voltage
drop has been output.)
Replace the SRS-ECU.

SRS – Troubleshooting52B-10
Code No.34 Connector lock systemProbable cause
This diagnosis code is output if a poor connection of the SRS-ECU is detected. However,
if the vehicle condition returns to normal, diagnosis code No.34 will be automatically
erased, and the SRS warning lamp will switch off.
Malfunction of connectors

Malfunction of SRS-ECU
Is B51 SRS-ECU connector correctly connected?Ye s
No
Repair
Check the following connector:
B-51
OK
Replace the SRS-ECU.ReplaceNG
Code No.35 SRS-ECU (deployed air bag) systemProbable cause
This diagnosis code is output after the air bag deploys. If this code is output before
the air bag has deployed, the cause is probably a malfunction inside the SRS-ECU.
Malfunction of SRS-ECU
Replace the SRS-ECU.
Code No.41 IG1 (A) power circuit systemProbable cause
This diagnosis code is output if the voltage between the IG1 (A) terminal and the
earth is lower than the specified value for a continuous period of 5 seconds or more.
However, if the vehicle condition returns to normal, diagnosis code No.41 will be
automatically erased, and the SRS warning lamp will switch off.
Malfunction of wiring harnesses or connectors

Malfunction of SRS-ECU
Measure at SRS check harness
connector (5).

Disconnect SRS-ECU
connector B-51.

Connect SRS check
harness connector (3).

Continuity between
terminals (20)
OK:ContinuityNGCheck the following
connectors:
B-51, B-78, B-80NG
Repair
OK
Check trouble symptoms.
NG
Check the harness wire between the SRS-ECU and earth, and
repair if necessary.
OK
Measure at SRS check harness connector (5).

Disconnect SRS-ECU connector B-51.

Connect SRS check harness connector (3).

Ignition switch: ON

Voltage between terminal (14) and body earth
OK:9 V or moreNGCheck the following
connectors:
B-51, B-78NG
Repair
OK
Check trouble symptoms.
NG
Check the harness wire between the SRS-ECU and ignition switch
IG
1, and repair if necessary.
OK
Replace the SRS-ECU.
SRS check harness
(MB991613)
3
5

SRS – Troubleshooting52B-11
Code No.42 IG1 (B) power circuit systemProbable cause
This diagnosis code is output if the voltage between the IG1 (B) terminal and the
earth is lower than the specified value for a continuous period of 5 seconds or more.
However, if the vehicle condition returns to normal, diagnosis code No.42 will be
automatically erased, and the SRS warning lamp will switch off.
Malfunction of wiring harnesses or connectors
NG
Check the harness wire between the SRS-ECU and ignition switch
IG
1, and repair if necessary.
OK
Check trouble symptoms.
OK
Replace the SRS-ECU.
OK
Measure at SRS check harness connector (5).

Disconnect SRS-ECU connector B-51.

Connect SRS check harness connector (3).

Ignition switch: ON

Voltage between terminal (13) and body earth
OK:9 V or moreNGCheck the following
connectors:
B-51, B-78NG
Repair
NG
Check the harness wire between the SRS-ECU and earth, and
repair if necessary.
OK
Check trouble symptoms.
Measure at SRS check harness
connector (5).

Disconnect SRS-ECU
connector B-51.

Connect SRS check
harness connector (3).

Continuity between
terminals (20)
OK:ContinuityNGCheck the following
connectors:
B-51, B-78, B-80NG
RepairSRS check harness
(MB991613)
3
5

SRS – Troubleshooting52B-12
Code No.43 SRS warning lamp drive circuit system
(Lamp does not illuminate.)Probable cause
This diagnosis code is output when an open circuit occurs for a continuous period
of 5 seconds while the SRS-ECU in monitoring the SRS warning lamp and the lamp
is OFF (transistor OFF).
However, if this code is output due to an open circuit, if the vehicle condition returns
to normal, this diagnosis code No.43 will be automatically erased, and the SRS warning
lamp will return to normal.
Malfunction of wiring harnesses or connectors

Blown bulb

Malfunction of SRS-ECU

Malfunction of combination meter
OK
Replace the combination
meter.
NG
Check the harness wire
between the SRS-ECU
and ignition switch (IG
1).NG
Repair
OK
Check trouble symptoms.
OK
Check the following
connectors:
B-51, B-09, B-08, B-75,
B-76NG
Repair
NG
Check the harness wire between the SRS-ECU and earth, and
repair if necessary.
OK
Check trouble symptoms.
Measure at SRS check harness
connector (5).

Disconnect SRS-ECU
connector B-51.

Connect SRS check
harness connector (3).

Continuity between
terminals (20)
OK:ContinuityNGCheck the following
connectors:
B-51, B-78, B-80NG
Repair
OK
Measure at SRS check harness connector (5).

Disconnect SRS-ECU connector B-51.

Connect SRS check harness connector (3).

Ignition switch: ON

Connect terminal (15) to the body earth.
OK:Lamp illuminatesNGBlown bulb inspectionNG
Repair
OK
Replace the SRS-ECU.
SRS check harness
(MB991613)
3
5
Code No.43 SRS warning lamp drive circuit system
(Lamp does not switch off.)
Probable cause
This diagnosis code is output when a short to earth occurs in the harness between
the lamp and the SRS-ECU while SRS-ECU is monitoring the SRS warning lamp
and the lamp is ON.
Malfunction of wiring harnesses or connectors

Malfunction of SRS-ECU

Malfunction of combination meter
SRS warning lamp inspection

Ignition switch: ON

Does lamp switch off when SRS-ECU connector B-51 is
disconnected?NoCheck the following
connectors:
B-51, B-09NG
Repair
Ye s
Replace the SRS-ECU.
OK
Check trouble symptoms.
NG
Check the harness wire
between the SRS-ECU
and combination meter,
and repair if necessary.

SRS – Troubleshooting52B-13
Code No.44 SRS warning lamp drive circuit systemProbable cause
This diagnosis code is output when a short occurs in the lamp drive circuit or a
malfunction of the output transistor inside the SRS-ECU is detected while the SRS-ECU
is monitoring the SRS warning lamp drive circuit.
Malfunction of wiring harnesses or connectors

Malfunction of SRS-ECU
Check the SRS warning lamp drive circuit system.
(Refer to P.52B-12)OKReplace the SRS-ECU.
Code No.45 SRS-ECU non-volatile memory (EEPROM)
and A/D converter systemProbable cause
This diagnosis code is output if there is a malfunction in the SRS-ECU non-volatile
memory (EEPROM) and A/D converter.
Malfunction of SRS-ECU
Code No.Trouble symptom
45Non-volatile memory
(EEPROM)
Non-volatile memory (EEPROM) is abnormal.
Replace the SRS-ECU.
Code No.51 or 52 Driver’s side air bag module (squib
ignition drive circuit) systemProbable cause
This diagnosis code is output if a short (No.51) or an open circuit (No.52) is detected
in the circuit for the driver’s seat.
Malfunction of SRS-ECU
Code No.Trouble symptom
51Driver’s side air bag module
(squib ignition drive circuit)

Short circuit in the squib ignition drive circuit
52
(squib ignition drive circuit)

Open circuit in the squib ignition drive circuit
Replace the SRS-ECU.
Code No.54 or 55 Front passenger’s side air bag module
(squib ignition drive circuit) systemProbable cause
This diagnosis code is output if a short (No.54) or an open circuit (No.55) is detected
in the circuit for the passenger’s seat.
Malfunction of SRS-ECU
Code No.Trouble symptom
54Front passenger’s side air
bag module (squib ignition

Short circuit in the squib ignition drive circuit
55
bag module (squib ignition
drive circuit)
Open circuit in the squib ignition drive circuit
Replace the SRS-ECU.

SRS – Troubleshooting52B-14
SRS WARNING LAMP INSPECTION
1. Check to be sure that the SRS warning lamp illuminates
when the ignition switch is in the ON position.
2. Check to be sure that it illuminates for approximately
7 seconds and then switches off.
3. If the above is not the cause, inspect the diagnosis codes.
INSPECTION CHART FOR TROUBLE SYMPTOMS
Get an understanding of the trouble symptoms and check according to the inspection procedure chart.
Trouble symptomInspection procedure No.Reference page
Communication with
MUT-II is not possible.Communication with all systems is not
possible.152B-14
Communication is not possible with
SRS only.252B-15
When the ignition key is turned to “ON” (engine stopped), the
SRS warning lamp does not illuminate.Refer to diagnosis code No.43.52B-12
After the ignition switch is turned to ON, the SRS warning lamp
is still on after approximately 7 seconds have passed.Refer to diagnosis code No.43.52B-12
INSPECTION PROCEDURE FOR TROUBLE SYMPTOMS
Inspection Procedure 1
Communication with MUT-II is not possible. (Communica-
tion with all systems is not possible.)
Probable cause
The cause is probably a power supply system (including earth circuit) of the diagnosis
line.
Malfunction of connectors

Malfunction of wiring harness
Refer to GROUP 13A – Troubleshooting.
SRS warning lamp

SRS – Troubleshooting / SRS Maintenance52B-15
Inspection Procedure 2
Communication with MUT-II is not possible.
(Communication is not possible with SRS only.)
Probable cause
If communication is not possible with the SRS only, the cause is probably an open circuit
in the diagnosis output circuit of the SRS or in the power circuit (including earth circuit).
Malfunction of wiring harnesses or connectors

Malfunction of SRS-ECU
OK
Check trouble symptoms.
NG
Check the harness wire between the SRS-ECU and earth, and
repair if necessary.
OK
Check trouble symptoms.
NG
Check the harness wire between the SRS-ECU and ignition switch
IG
1, and repair if necessary.
Measure at SRS check harness
connector (5).

Disconnect SRS-ECU
connector B-51.

Connect SRS check
harness connector (3).

Continuity between
terminals (20)
OK:ContinuityNGCheck the following
connectors:
B-51, B-78, B-80NG
RepairSRS check harness
(MB991613)
3
5
OK
Replace the SRS-ECU.
OK
Check the harness wire between the SRS-ECU and diagnosis
connector.NG
Repair
OK
Measure at SRS check harness connector (5).

Disconnect SRS-ECU connector B-51.

Connect SRS check harness connector (3).

Ignition switch: ON

Voltage between terminal (13) and body earth
OK:9 V or more

Voltage between terminal (14) and body earth
OK:9 V or moreNGCheck the following
connectors:
B-51, B-78, B-76NG
Repair
SRS MAINTENANCE
The SRS must be inspected by an authorized dealer 10 years
after the date of vehicle registration.
SRS WARNING LAMP CHECK
Turn the ignition key to the “ON” position. Does the SRS
warning lamp illuminate for about 7 seconds, turn off and
then remain extinguished for at least 5 seconds? If yes, SRS
system is functioning properly. If no, consult page 52B-6.
SRS warning lamp

SRS – SRS Maintenance52B-16
SRS COMPONENT VISUAL CHECK
Turn the ignition key to the LOCK (OFF) position, disconnect
the negative battery cable and tape the terminal.
Caution
Wait at least 60 seconds after disconnecting the battery
cable before doing any further work. (Refer to P.52B-3.)
SRS CONTROL UNIT (SRS-ECU)
1. Check SRS-ECU case and brackets for dents, cracks,
deformation or rust.
Caution
The SRS may not activate if the SRS-ECU is not
installed properly, which could result in serious injury
or death to the vehicle’s driver or front passenger.
2. Check connector for damage, and terminals for
deformation or rust.
Replace SRS-ECU if it fails visual check.
(Refer to P.52B-24.)
AIR BAG MODULES, STEERING WHEEL AND CLOCK
SPRING
1. Remove the air bag modules, steering wheel and clock
spring. (Refer to P.52B-25.)
Caution
The removed air bag modules should be stored in
a clean, dry place with the pad cover face up.
2. Check pad cover for dents, cracks or deformation.
Insulating tape
Battery
Battery (–) cable
SRS-ECU
Pad cover


Pad cover