Mitsubishi Lancer Evolution IX. Manual - part 627

TROUBLESHOOTING

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-21

Code No.22: Driver's air bag module (squib) system (open-circuited in the squib circuit)

OPERATION

• The SRS-ECU judges how severe a collision is 

by detecting signals from the front impact sensors 
and the front air bag analogue G-sensor. If the 
impact is over a predetermined level, the 
SRS-ECU outputs an ignition signal. At this time, 
if the front air bag safing G-sensor is on, the SRS 
air bag will inflate. 

• The ignition signal is input to the air bag module 

via the clock spring to inflate the air bag.

DIAGNOSIS CODE SET CONDITIONS

This diagnosis code is set if driver’s air bag squib 
wire(s) are open-circuited. However, if no diagnosis 
code resets, the SRS warning lamp will be switched 
off (diagnosis code will be retained). 

PROBABLE CAUSES

• Open circuit in the clock spring

• Open circuit due to improper neutral position of 

the clock spring

• Open circuit in the driver's air bag module (squib) 

circuit

• Disengaged driver's air bag module (squib) con-

nector

• Improper connector contact

• Malfunction of the SRS-ECU

CONNECTOR
LOCK
SWITCH

CONNECTOR
LOCK
SWITCH

CONNECTOR
LOCK
SWITCH

CLOCK
SPRING

AIR BAG MODULE
(SQUIB)
(DRIVER'S SIDE)

AIR BAG
DRIVE CIRCUIT

SRS-ECU

MICROCOMPUTER

Wire colour code
B : Black     LG : Light green     G : Green     L : Blue     W : White     Y : Yellow     SB : Sky blue
BR : Brown     O : Orange     GR : Gray     R : Red     P : Pink     V : Violet

NOTE

: CONNECTOR
  COUPLED: ON
  CONNECTOR
  UNCOUPLED: OFF

Driver's Air Bag Module (Squib) Circuit

: LH drive  vehicles
: RH drive  vehicles

TROUBLESHOOTING

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-22

DIAGNOSIS PROCEDURE

STEP 1. Check the diagnosis code by connecting 
a dummy resistor. (M.U.T.-II/III diagnosis code)
(1) Disconnect the negative battery terminal.

(2) By sliding the A section (in the figure) of air bag 

module connector C-201 in the arrow direction, 
disconnect the connector.

(3) Connect special tool dummy resistor (MB991865) 

to special tool resistor harness (MB991866).

CAUTION

Do not insert a test probe into the terminal from 
its front side directly as the connector contact 
pressure may be weakened.
(4) Insert special tool (MB991866) into clock spring 

side air bag module connector C-201 by 
backprobing.

(5) Connect the negative battery terminal.
(6) Erase the diagnosis code memory, and check the 

diagnosis code.

Q:  Is diagnosis code 22 set?

YES : 

Go to Step 2.

NO : 

Replace the driver's air bag module (Refer 
to 

P.52B-110

). 

STEP 2. Check the diagnosis code by connecting 
a dummy resistor. (M.U.T.-II/III diagnosis code)
(1) Disconnect the negative battery terminal.

(2) Disconnect the clock spring connector C-205.

(3) Connect special tool dummy resistor (MB991865) 

to special tool resistor harness (MB991866).

CAUTION

Do not insert a test probe into the terminal from 
its front side directly as the connector contact 
pressure may be weakened.
(4) Insert special tool (MB991866) into clock spring 

harness side connector C-205 (terminal No.3 and 
4) by backprobing.

(5) Connect the negative battery terminal.
(6) Erase the diagnosis code memory, and check the 

diagnosis code.

AC105823

AC304700

AC305145AE

A

Steering
wheel

C-201 Air bag 
module connector

AC300945AE

MB991865
(Dummy resistor : 3 )

MB991866
(Resistor harness)

C-201 Air bag 
module
connector

AC310479

AG

Connector: C-205 <LHD>

C-205 (Y)

Harness side 
connector 
(rear view)

AC310481AG

Connector: C-205 <RHD>

C-205 (Y)

Harness side 
connector 
(rear view)

AC300949AC

MB991865 (Dummy
resistor : 3  )

MB991866
(Resistor harness)

C-205 Clock spring
connector

(Rear view)

TROUBLESHOOTING

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-23

Q: Is diagnosis code 22 set?

YES : 

Go to Step 3.

NO : 

Replace the clock spring (Refer to 

P.52B-110

).

STEP 3. Resistance measurement between the 
SRS-ECU connector C-12 (terminal No.11 and 12) 
and the clock spring connector C-205 (terminal 
No.3 and 4)

(1) Disconnect SRS-ECU connector C-12 and clock 

spring connector C-205.

CAUTION

Do not insert a test probe into the terminal from 
its front side directly as the connector contact 
pressure may be weakened.
(2) Resistance measurement between the following 

terminals. 

• SRS-ECU connector C-12 terminal No.11 and 

the clock spring connector C-205 terminal 
No.3

• SRS-ECU connector C-12 terminal No.12 and 

the clock spring connector C-205 terminal 
No.4

OK: Less than 2 

Ω

Q: Are the check results normal? 

YES : 

Go to Step 4. 

NO : 

Repair the harness wires between 
SRS-ECU connector C-12 (terminal No.11 
and 12) and clock spring connector C-205 
(terminal No.3 and 4).

STEP 4. Check whether the diagnosis code is 
reset.

Q: Is diagnosis code 22 set?

YES : 

Replace the SRS-ECU (Refer to 

P.52B-109

).

NO : 

An intermittent malfunction is suspected 
(Refer to GROUP 00 

− How to Use 

Troubleshooting/Inspection Service Points 

P.00-5

). 

AC101950AJ

SRS-ECU

Harness side 
connector 
(rear view)
 

C-12 (Y)

Connector: C-12

AC310479

AG

Connector: C-205 <LHD>

C-205 (Y)

Harness side 
connector 
(rear view)

AC310481AG

Connector: C-205 <RHD>

C-205 (Y)

Harness side 
connector 
(rear view)

1 2

4

3

AC200924

13 14 15 16 17 18 19 20

5 6 7 8 9 10 11 12

1 2

3 4

C-12 Harness 
side connector 
(rear view)

C-205 Harness 
side connector 
(rear view)

AJ

TROUBLESHOOTING

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-24

Code No.24: Passenger's (front) air bag module (squib) system (short-circuited between terminals of 
the squib circuit)

OPERATION

• The SRS-ECU judges how severe a collision is 

by detecting signals from the front impact sensors 
and the front air bag analogue G-sensor. If the 
impact is over a predetermined level, the 
SRS-ECU outputs an ignition signal. At this time, 
if the front air bag safing G-sensor is on, the SRS 
air bag will inflate. 

• The ignition signal is input to the air bag module 

to inflate the air bag.

DIAGNOSIS CODE SET CONDITIONS

This diagnosis code is set if one passenger’s (front) 
air bag squib wire shorted to the other. However, if no 
diagnosis code resets, the SRS warning lamp will be 
switched off (diagnosis code will be retained). 

PROBABLE CAUSES

• Improper engaged connector or defective short 

spring*

• Short circuit between the passenger's (front) air 

bag module (squib) circuit terminals

• Damaged connector(s)

• Malfunction of the SRS-ECU

NOTE:  *: The squib circuit connectors integrate a 
"short" spring (which prevents the air bag from 
deploying unintentionally due to static electricity by 
shorting the positive wire to the earth wire in the 
squib circuit when the connectors are discon-
nected).Therefore, if connector C-12 or C-106 is 
damaged or improperly engaged, the short spring 
may not be released when the connector is con-
nected.

DIAGNOSIS PROCEDURE

STEP 1. M.U.T.-II/III diagnosis code

CAUTION

To prevent damage to M.U.T.-II/III, always turn the 
ignition switch to the "LOCK" (OFF) position 
before connecting or disconnecting M.U.T.-II/III.
(1) Turn the ignition switch to the "ON" position.
(2) Check if the diagnosis code is set.
(3) Turn the ignition switch to the "LOOK" (OFF) 

position.

Q: Is diagnosis code 34 set?

YES : 

Go to Step 2.

NO : 

Go to Step 3.

CONNECTOR
LOCK
SWITCH

CONNECTOR
LOCK
SWITCH

AIR BAG DRIVE
CIRCUIT

MICROCOMPUTER

SRS-ECU

AIR BAG MODULE
(SQUIB)
(PASSENGER'S SIDE)

Wire colour code
B : Black     LG : Light green
G : Green     L : Blue
W : White     Y : Yellow
SB : Sky blue     BR : Brown
O : Orange     GR : Gray
R : Red     P : Pink     V : Violet

Passenger's (Front) Air Bag Module (Squib) Circuit

NOTE

: CONNECTOR
  COUPLED: ON
  CONNECTOR
  UNCOUPLED: OFF

: LH drive  vehicles
: RH drive  vehicles