Mitsubishi Colt Ralliart. Manual - part 549

TROUBLESHOOTING

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-34

(5) Resistance measurement between C-13 curtain 

air bag module (LH) side connector terminals 1 
and 2.

OK: Open circuit

Q: Is the check result normal?

YES : 

Replace the curtain air bag module (Refer 

to 

P.52B-152

).

NO : 

Repair the harness wire between curtain air 
bag module (LH) side connector C-13 
(terminal No.1 and 2) and curtain air bag 
module connector C-10 (terminal No.1 and 
2).

STEP 7. Check whether the diagnosis code is 
reset. 

Q: Is diagnosis code 4A set?

YES : 

Replace the SRS-ECU (Refer to 

P.52B-143

).

NO : 

An intermittent malfunction is suspected 
(Refer to GROUP 00, How to Cope with 
Intermittent Malfunction 

P.00-13

).

Code No.4B: Curtain air bag module (squib) (LH) system (open-circuited in the squib circuit)

OPERATION

The SRS-ECU judges how severe a collision is by 
detecting signals from the side impact sensors and 
the side-airbag safing G-sensor. If the impact is over 
a predetermined level, the SRS-ECU sends an igni-
tion signal. At this time, if the side-airbag safing 
G-sensor is on, the curtain air bag module will 
deploy. 

DIAGNOSIS CODE SET CONDITIONS

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

AC510222

CURTAIN AIR BAG
MODULE (SQUIB)
(LH)

AIR BAG
DRIVE CIRCUIT

SRS-ECU

MICRO COMPUTER

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

CONNECTOR
LOCK
SWITCH

CONNECTOR
LOCK
SWITCH

NOTE

CONNECTOR
COUPLED: ON
CONNECTOR
UNCOUPLED: OFF

Curtain Air Bag Module (Squib) (LH) Circuit

AB

Main

Index

Group

TOC

TROUBLESHOOTING

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-35

PROBABLE CAUSES

• Improper connector contact

• Open circuit in the curtain air bag module (squib) 

(LH) circuit

• Malfunction of the SRS-ECU

DIAGNOSIS PROCEDURE

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

(2) Disconnect intermediate connector C-13 

(connection between curtain air bag wiring 
harness and instrument panel wiring harness).

(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) Connect special tool (MB991866) to the C-13 

harness side connector by backprobing.

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

the diagnosis code.

Q: Is diagnosis code 4B set?

YES : 

Go to Step 2.

NO : 

Go to Step 3.

STEP 2. Resistance measurement between 
SRS-ECU connector B-34 (terminal No.27 and 28) 
and harness side connector C-13 (terminal No.2 
and 1).
(1) Disconnect the negative battery terminal.

(2) Disconnect SRS-ECU connector B-34.

(3) Disconnect intermediate connector C-13 

(connection between curtain air bag wiring 
harness and instrument panel wiring harness).

CAUTION

Do not insert a test probe into the terminal from 
its front side directly as the connector contact 
pressure may be weakened.

(4) Resistance measurement between the following 

terminals. 

• SRS-ECU connector B-34 terminal No.27 and 

harness side connector C-13 terminal No.2

• SRS-ECU connector B-34 terminal No.28 and 

harness side connector C-13 terminal No.1

OK: Continuity (Less than 2 

Ω)

AC209027

Connector: C-13 

C-13 (R)

Quarter panel

AC

Harness side

AC006042 CK

MB991866
(Resistor harness)

C-13 

Intermediate h

arness side

connector

MB991865 (Dummy
resistor: 3

 

Ω)

C-13 Curtain air bag
module (LH) side connector

AC206285

AG

B-34 (Y)

Connector: B-34

Harness side 
connector 
(rear view)

343536373839404142

252627282930313233

2122

2324

AC209027

Connector: C-13 

C-13 (R)

Quarter panel

AC

Harness side

AC208817

34 35 36 37 38 39 40 41 42

25 26 27 28 29 30 31 32 33

21 22

23 24

1 2

B-34 
Harness side 
connector 
(rear view)

C-13 Harness side 
connector

AD

Main

Index

Group

TOC

TROUBLESHOOTING

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-36

Q: Are the check results normal?

YES : 

Go to Step 4.

NO : 

Repair the harness wire between SRS-ECU 
connector B-34 (terminal No.27 and 28) and 
harness side connector C-13 (terminal No.2 
and 1).

STEP 3. Resistance measurement between 
curtain air bag module (LH) side connector C-13 
(terminal No.1 and 2) and the curtain air bag 
module C-10 (terminal No.1 and 2).
(1) Disconnect the negative battery terminal.

(2) Disconnect harness side connector C-13 and 

curtain air bag module connector C-10, and 
measure at the wiring harness side. For 
connector C-10, use a flat-tipped screwdriver to 
pull out the locking button at the harness side 
connector, and then disconnect the connector.

(3) Connect C-10 harness side connector to special 

tool resistor harness (MB991884).

CAUTION

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

terminals. 

• curtain air bag module (LH) side connector 

C-13 terminal No.1 and special tool terminal 
No.2

• curtain air bag module (LH) side connector 

C-13 terminal No.2 and special tool terminal 
No.1

OK: Continuity (Less than 2 

Ω)

Q: Are the check results normal?

YES : 

Replace the curtain air bag module (Refer 

to 

P.52B-152

).

NO : 

Repair the harness wire between curtain air 
bag module (LH) side connector C-13 
(terminal No.1 and 2) and curtain air bag 
module connector C-10 (terminal No.1 and 
2).

STEP 4. Check whether the diagnosis code is 
reset.

Q: Is diagnosis code No.4B set?

YES : 

Replace the SRS-ECU (Refer to 

P.52B-143

). 

NO : 

An intermittent malfunction is suspected 
(Refer to GROUP 00, How to Cope with 
Intermittent Malfunction 

P.00-13

).

AC401577

Connectors: C-10, C-13

C-10 (B)

Harness side
connector
(front view)

AF

C-13 (R)

Harness side
connector

AC208384BK

C-10
Curtain air bag
module connector 

Flat-tipped 
screwdriver

Locking button

C-10
Harness side
connector

AC201287BS

C-10 

Harness side
connector

MB991884

1 2

2

1

AC303565AF

Resister harness 
connector

C-13 Curtain air bag module (LH) 
side connector (rear view)

Main

Index

Group

TOC

TROUBLESHOOTING

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-37

Code No.4E: Curtain air bag module (squib) (LH) system (short-circuited to the power supply)

OPERATION

The SRS-ECU judges how severe a collision is by 
detecting signals from the side impact sensors and 
the side-airbag safing G-sensor. If the impact is over 
a predetermined level, the SRS-ECU sends an igni-
tion signal. At this time, if the side-airbag safing 
G-sensor is on, the curtain air bag module will 
deploy. 

DIAGNOSIS CODE SET CONDITIONS

This diagnosis code is set if the curtain air bag mod-
ule squib (LH) wire(s) are short-circuited to the power 
supply.

PROBABLE CAUSES

• Damaged wiring harnesses or connectors

• Short to the power supply in the curtain air bag 

module (squib) (LH) harness

• Malfunction of the SRS-ECU

DIAGNOSIS PROCEDURE

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

(2) Disconnect intermediate connector C-13 

(connection between curtain air bag wiring 
harness and instrument panel wiring harness). 

AC510222

CURTAIN AIR BAG
MODULE (SQUIB)
(LH)

AIR BAG
DRIVE CIRCUIT

SRS-ECU

MICRO COMPUTER

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

CONNECTOR
LOCK
SWITCH

CONNECTOR
LOCK
SWITCH

NOTE

CONNECTOR
COUPLED: ON
CONNECTOR
UNCOUPLED: OFF

Curtain Air Bag Module (Squib) (LH) Circuit

AB

AC209027

Connector: C-13 

C-13 (R)

Quarter panel

AC

Harness side

Main

Index

Group

TOC