1999 MITSUBISHI LANCER EVOLUTION VI Workshop Manual

52B-1
SUPPLEMENTAL
RESTRAINT
SYSTEM (SRS)
CONTENTS
GENERAL INFORMATION 2. . . . . . . . . . . . . . . .
SRS SERVICE PRECAUTIONS 3. . . . . . . . . . .
SPECIAL TOOLS 5. . . . . . . . . . . . . . . . . . . . . . . .
TEST EQUIPMENT 5. . . . . . . . . . . . . . . . . . . . . .
TROUBLESHOOTING 6. . . . . . . . . . . . . . . . . . . .
SRS MAINTENANCE 15. . . . . . . . . . . . . . . . . . .
POST-COLLISION DIAGNOSIS 19. . . . . . . . .
INDIVIDUAL COMPONENT SERVICE 22. . . WARNING/CAUTION LABELS 23. . . . . . . . . .
SRS AIR BAG CONTROL UNIT
(SRS-ECU) 24. . . . . . . . . . . . . . . . . . . . . . . . . . . .
AIR BAG MODULES AND CLOCK
SPRING 25. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
AIR BAG MODULE DISPOSAL
PROCEDURES 32. . . . . . . . . . . . . . . . . . . . . . . .
Undeployed Air Bag Module Disposal
Procedures 32. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Deployed Air Bag Module Disposal
Procedures 40. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
CAUTION

Carefully read and observe the information in the SERVICE PRECAUTIONS (P.52B-3.) prior to any service.

For information concerning troubleshooting or maintenance, always observe the procedures in the Troubleshooting
(P.52B-6.) section.

If any SRS components are removed or replaced in connection with any service procedures, be sure to follow the
procedures in the INDIVIDUAL COMPONENT SERVICE section (P.52B-22.) for the components involved.

If you have any questions about the SRS, please contact your local distributor.

SRS – General Information52B-2
GENERAL INFORMATION
To improve safety, the SRS is available as optional
part.
The SRS consists of two air bag modules, SRS
air bag control unit (SRS-ECU), SRS warning lamp
and clock spring. One air bag is located in the
centre of the steering wheel and another above
the glove box. Each air bag has a folded air bag
and an inflator unit. The control unit under the floor
console monitors the system and has a safing G
sensor and an analog G sensor. The warning lamp
on the instrument panel indicates the operationalstatus of the SRS. The clock spring is installed
in the steering column.
Only authorized service personnel should do work
on or around the SRS components. Those service
personnel should read this manual carefully before
staring any such work. Extreme care must be used
when servicing the SRS to avoid injury to the service
personnel (by inadvertent deployment of the air
bags) or the driver (by rendering the SRS
inoperative).
Air bag module
(Driver’s side)Clock springAir bag module
(Front passenger’s side)
Diagnosis
connector
SRS-ECU
SRS warning lamp

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 – Special Tools / Test Equipment52B-5
SPECIAL TOOLS
ToolNumberNameUse
MB991502MUT-II sub
assembly
Reading diagnosis codes

Erasing diagnosis code

Reading trouble period

Reading erase times
MB991613SRS check
harnessChecking the SRS electrical circuitry
MB990803Steering wheel
pullerSteering wheel removal
MB686560SRS air bag
adapter harness A
Deployment of air bag modules and seat
belt with pre-tensioner inside the vehicle

Deployment of air bag module (front
passenger’s side) outside the vehicle
MR203491 or
MB628919SRS air bag
adapter harness BDeployment of air bag module (driver’s side)
outside the vehicle
TEST EQUIPMENT
ToolNameUse
Digital multi-meterChecking the SRS electrical circuitry
Use a multi-meter for which the
maximum test current is 2 mA or less
at the minimum range of resistance
measurement

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