1999 MITSUBISHI LANCER EVOLUTION VI ECU

SRS – SRS Service Precautions52B-3
SRS SERVICE PRECAUTIONS
1. In order to avoid injury to yourself or others
from accidental deployment of the air bag during
servicing, read and carefully follow all the
precautions and procedures described in this
manual.
2. Do not use any electrical test equipment on
or near SRS components, except those
specified on P.52B-5.
3. Never Attempt to Repair the Following
Components:

SRS air bag control unit (SRS-ECU)

Clock Spring

Air Bag Module
(Driver‘s side or front passenger’s side*)NOTE
*: Vehicles with front passenger’s air bag
If any of these components are diagnosed as
faulty, they should only be replaced, in
accordance with the INDIVIDUAL COM-
PONENT SERVICE procedures in this manual,
starting at page 52B-22.
4. After disconnecting the battery cable, wait 60 seconds
or more before proceeding with the following work.
The SRS system is designed to retain enough voltage
to deploy the air bag for a short time even after the
battery has been disconnected, so serious injury may
result from unintended air bag deployment if work
is done on the SRS system immediately after the
battery cables are disconnected.
5. Do not attempt to repair the wiring harness connectors
of the SRS. If any of the connectors are diagnosed as
faulty, replace the wiring harness. If the wires are
diagnosed as faulty, replace or repair the wiring harness
according to the following table.
Battery Insulating tape
SRS-ECU connector

SRS – SRS Service Precautions52B-4
SRS-ECU
terminal No.Harness connector
(No. of terminals,
colour)Destination of harnessCorrective action
1 to 421 pins, yellow––
5Body wiring harness → Clock spring → Air bag
module (Driver’s side)
Correct or replace each
wiring harness Replace
6
module (Driver’s side)wiring harness. Replace
clock spring.
7*Body wiring harness → Air bag module (Front
passenger’s side)
Correct or replace each
wiring harness
8*
passenger’s side)wiring harness.
9,10––
11Body wiring harness → Diagnosis connectorCorrect or replace each
wiring harness.
12––
13Body wiring harness → Junction block (fuse No.2)Correct or replace each
wiring harness
14Body wiring harness → Junction block (fuse No.4)
wiring harness.
15Body wiring harness → SRS warning lamp
16 to 19––
20Body wiring harness → EarthCorrect or replace each
wiring harness.
21––
NOTE
*: Vehicles with front passenger’s air bag
6. 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.
7. Whenever you finish servicing the SRS, check warning lamp operation to make sure that the system
functions properly. (Refer to P.52B-14.)
8. Make certain that the ignition switch is LOCK (OFF) position when the MUT-II is connected or
disconnected.
9. If you have any questions about the SRS, please contact your local distributor.
NOTE
SERIOUS INJURY CAN RESULT FROM UNINTENDED AIR BAG DEPLOYMENT, SO USE ONLY
THE PROCEDURES AND EQUIPMENT SPECIFIED IN THIS MANUAL.

SRS – Troubleshooting52B-6
TROUBLESHOOTING
STANDARD FLOW OF DIAGNOSTIC TROUBLESHOOTING
Refer to GROUP 00 – How to Use Troubleshooting/Inspection Service Points.
DIAGNOSIS FUNCTION
DIAGNOSIS CODES CHECK
Connect the MUT-II to the diagnosis connector (16-pin) under the instrument under cover, then check
diagnosis codes.
(Refer to GROUP 00 – How to Use Troubleshooting/Inspection Service Points.)
ERASING DIAGNOSIS CODES
Connect the MUT-II to the diagnosis connector and erase the diagnosis code.
Caution
Turn off the ignition switch before connecting or disconnecting the MUT-II.
INSPECTION CHART FOR DIAGNOSIS CODES
Inspect according to the inspection chart that is appropriate for the malfunction code.
Code No.Diagnosis itemReference page
14Analog G-sensor system in the SRS-ECU52B-7
15,16Safing G-sensor system in the SRS-ECU52B-7
21, 22, 61, 62Driver’s side air bag module (squib) system52B-8
24, 25, 64, 65Front passenger’s side air bag module (squib) system52B-9
31, 32SRS-ECU capacitor system52B-9
34*Connector lock system52B-10
35SRS-ECU (deployed air bag) system52B-10
41*IG1 (A) power circuit system52B-10
42*IG1 (B) power circuit system52B-11
43SRS warning lamp drive circuit
system
Lamp does not illuminate.*52B-12
systemLamp does not switch off.52B-12
44SRS warning lamp drive circuit system52B-13
45SRS-ECU non-volatile memory (EEPROM) and A/D converter system52B-13
51, 52Driver’s side air bag module (squib ignition drive circuit) system52B-13
54, 55Front passenger’s side air bag module (squib ignition drive circuit) system52B-13
NOTE
(1) *: If the vehicle condition returns to normal, the diagnosis code will be automatically erased, and the SRS warning
lamp will return to normal.
(2) If the vehicle has a discharged battery it will store the fault codes 41 or 42. When these diagnosis codes are
displayed, check the battery.

SRS – Troubleshooting52B-7
INSPECTION PROCEDURE CLASSIFIED BY DIAGNOSIS CODE
Code No.14 Analog G-sensor system in the SRS-ECUProbable cause
The SRS-ECU monitors the output of the analog G-sensor inside the SRS-ECU.
It outputs this code when any of the following are detected.

When the analog G-sensor is not operating

When the characteristics of the analog G-sensor are abnormal

When the output from the analog G-sensor is abnormal
Malfunction of SRS-ECU
Replace the SRS-ECU.
Code No.15, 16 Safing G-sensor system in the SRS-ECUProbable cause
This code is output if there is a short or open circuit between the terminals of the
safing G-sensor inside the SRS-ECU.
The trouble causes for each diagnosis code No. are as follows.
Malfunction of SRS-ECU
Code No.Trouble symptom
15Short circuit in the safing G-sensor
16Open circuit in the safing G-sensor
Replace the SRS-ECU.

SRS – Troubleshooting52B-8
Code No.21, 22, 61 or 62 Driver’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 clock spring

Partial disconnection due to incorrect clock spring
neutral position

Malfunction of wiring harnesses or connectors

Malfunction of driver’s side air bag module (squib)

Malfunction of SRS-ECU
Code No.Trouble symptom
21
Short in driver’s side air bag module (squib) or harness short

Short in clock spring

Malfunction of connector*
22
Open circuit in driver’s side air bag module (squib) or open harness

Open circuit in clock spring

Malfunction of connector contact
61
Short in driver’s side air bag module (squib) harness leading to the power supply
62
Short in driver’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.
MUT-II Self-diag code

Disconnect clock spring
connector B-82.

Connect SRS check har-
ness connector (1).

Erase diagnosis code
memory.
Are code Nos.21, 22, 61 or
62 output?Ye sCheck the following
connectors:
B-82, B-51NG
Repair
OK
Check trouble symptoms.
NG
Check the harness wire
between the SRS-ECU
and clock spring.NG
Repair
OK
Replace the SRS-ECU.
No
Check the clock spring. (Refer to P.52B-30.)NG
Repair
OK
Replace the driver’s side air bag module.
SRS check harness
(MB991613)
Body wiring
harness
Clock spring
1

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