1999 MITSUBISHI LANCER EVOLUTION VI ECU

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 – 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

SRS – Post-collision Diagnosis52B-19
POST-COLLISION DIAGNOSIS
To inspect and service the SRS after a collision (whether
or not the air bags have deployed), perform the following
steps.
SRS-ECU MEMORY CHECK
1. Connect the MUT-II to the diagnosis connector (16-pin).
Caution
Make certain that the ignition switch is OFF when
the MUT-II is connected or disconnected.
2. Read (and write down) all displayed diagnosis codes.
(Refer to P.52B-6.)
NOTE
If the battery power supply has been disconnected or
disrupted by the collision, the MUT-II cannot communicate
with the SRS-ECU. Inspect and, if necessary, repair the
body wiring harness before proceeding further.
3. Read the data list (fault duration and how many times
memories are erased) using the MUT-II.
Data list
NoService Data ItemApplicability
92Number indicating houw often the memory is clearedMaximum time to be stored: 250
93How long a problem has lasted (How long it takes
from the occurrence of the problem till the first igniting
signal)Maximum time to be stored: 9,999 minutes
(approximately 7 days)
94How long a problem has lasted (How long it takes
from the first igniting signal till now)
4. Erase the diagnosis codes and after waiting 5 seconds
or more read (and write down) all displayed diagnosis
codes. (Refer to P.52B-6.)

SRS – Post-collision Diagnosis52B-20
REPAIR PROCEDURE
WHEN AIR BAG DEPLOYS IN A COLLISION.
1. Replace the following parts with new ones.

SRS-ECU (Refer to P.52B-24.)

Air bag module (Refer to P.52B-25.)
2. Check the following parts and replace if there are any
malfunctions.

Clock spring (Refer to P.52B-25.)

Steering wheel, steering column and intermediate
joint
(1) Check wiring harness (built into steering wheel)
and connectors for damage, and terminals for
deformation.
(2) Install air bag module to check fit or alignment
with steering wheel.
(3) Check steering wheel for noise, binds or difficult
operation and excessive free play.
3. Check harnesses for binding, connectors for damage,
poor connections, and terminals for deformation.
(Refer to P.52B-18.)
WHEN AIR BAG DOES NOT DEPLOY IN LOW-SPEED
COLLISION.
Check the SRS components. If the SRS components are
showing any visible damage such as dents, cracks, or
deformation, replace them with new ones. Concerning parts
removed for inspection, replacement with new parts and
cautionary points for working, refer to appropriate INDIVIDUAL
COMPONENT SERVICE, P.52B-22.

SRS – Post-collision Diagnosis52B-21
SRS-ECU
1. Check SRS-ECU case and brackets for dents, cracks
or deformation.
2. Check connector for damage, and terminals for
deformation.
Air bag modules
1. Check pad cover for dents, cracks or deformation.
2. Check connector for damage, terminals deformities, and
harness for binds.
3. Check air bag inflator case for dents, cracks or deformities.
4. Install air bag module to steering wheel to check fit or
alignment with the wheel.
Clock spring
1. Check clock spring connectors and protective tube for
damage, and terminals for deformation.
2. Visually check the case for damage.
SRS-ECU

Connector

Inflator case
ConnectorInflator case
Case Protective tube
Protective tube

SRS – Post-collision Diagnosis / Individual Component Service52B-22
Steering wheel, steering column and intermediate joint
1. Check wiring harness (built into steering wheel) and
connectors for damage, and terminals for deformation.
2. Install air bag module to check fit or alignment with steering
wheel.
3. Check steering wheel for noise, binds or difficult operation
and excessive free play.
Harness connector (body wiring harness)
Check harnesses for binding, connectors for damage, poor
connection, and terminals for deformation. (Refer to P.52B-18.)
INDIVIDUAL COMPONENT SERVICE
If the SRS components are to be removed or replaced as a result of maintenance, troubleshooting,
etc., follow each procedure (P.52B-24 – P.52B-31)
Caution
1. SRS components should not be subjected to hear over 93C, so remove the SRS-ECU, air
bag module and clock spring before drying or baking the vehicle after painting.
Recheck SRS system operability after re-installing them.
2. If the SRS components are removed for the purpose of check, sheet metal repair, painting,
etc., they should be stored in a clean, dry place until they are reinstalled.