Mitsubishi Colt Ralliart. Manual — part 553

TROUBLESHOOTING

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-50

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 sends 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 B-06 or B-35 is dam-
aged or improperly engaged, the short spring may
not be released when the connector is connected.

DIAGNOSIS PROCEDURE

STEP 1. M.U.T.-III diagnosis code.

Q: Is diagnosis code 34 set?

YES :

Go to Step 2.

NO :

Go to Step 3.

AC510225

CONNECTOR
LOCK SWITCH

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

SRS-ECU

CONNECTOR
LOCK SWITCH

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

NOTE

: CONNECTOR COUPLED: ON
CONNECTOR UNCOUPLED: OFF

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

AB

Main

Index

Group

TOC

TROUBLESHOOTING

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-51

STEP 2. Connector lock check: SRS-ECU
connector B-35. (M.U.T.-III diagnosis code)
(1) Disconnect the negative battery terminal.

(2) Disconnect the connectors B-35 and then

reconnect them.

(3) Connect the negative battery terminal.
(4) Erase the diagnosis code memory, and check the

diagnosis code.

Q: Is diagnosis code 24 set?

YES :

Go to Step 4.

NO :

The procedure is complete. It is assumed
that diagnosis code 24 set as connector
B-35 was engaged improperly.

STEP 3. Connector lock check: SRS-ECU
connector B-35 and passenger’s (front) air bag
module connector B-06. (M.U.T.-III diagnosis
code)
(1) Disconnect the negative battery terminal.

(2) Disconnect connectors B-06 and B-35, and then

reconnect them.

(3) Connect the negative battery terminal.
(4) Erase the diagnosis code memory, and check the

diagnosis code.

Q: Is diagnosis code 24 set?

YES :

Go to Step 4.

NO :

The procedure is complete. It is assumed
that diagnosis code 24 set as connector
B-06 or B-35 was engaged improperly.

STEP 4. Check the diagnosis code by connecting
a dummy resistor. (M.U.T.-III diagnosis code)
(1) Disconnect the negative battery terminal.

(2) Unclip passenger’s (front) air bag module

connector B-06.

(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) Disconnect the passenger's (front) air bag

module connector B-06 and insert special tool
(MB991866) into the harness side connector by
backprobing.

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

diagnosis code.

Q: Is diagnosis code 24 set?

YES :

Go to Step 5.

NO :

Replace the passenger's (front) air bag
module (Refer to

P.52B-145

).

AC206285

AF

B-35 (Y)

Connector: B-35

Harness side
connector
(rear view)

AC206285

AF

B-35 (Y)

Connector: B-35

Harness side
connector
(rear view)

AC206286

Connector: B-06

2 1

Harness side
connector (front view)

B-06 (R)

AE

Glove box striker

AC206286

Connector: B-06

2 1

Harness side
connector (front view)

B-06 (R)

AE

Glove box striker

AC300956 AN

MB991865
(Dummy resistor: 3 )

MB991866

(Resistor harness)

B-06
Passenger's (front)
air bag module connector

B-06

Harness side

connector

Main

Index

Group

TOC

TROUBLESHOOTING

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-52

STEP 5. Resistance measurement at SRS-ECU
connector B-35.
(1) Disconnect the negative battery terminal.

(2) Disconnect SRS-ECU connector B-35.

(3) Unclip passenger’s (front) air bag module

connector B-06.

DANGER

To prevents the air bag from deploying unin-
tentionally, disconnect the passenger’s
(front) air bag module connector B-06 to
short the squib circuit.

(4) Disconnect the passenger's (front) air bag

module connector B-06.

CAUTION

Insert an insulator such as a cable tie to a depth
of 4 mm or more, otherwise the short spring will
not be released.

(5) Insert a cable tie [3 mm wide, 0.5 mm thick]

between terminals 9, 10 and the short spring to
release the short spring.

CAUTION

Do not insert a test probe into the terminal from
its front side directly as the connector contact
pressure may be weakened.
(6) Resistance measurement between B-35 harness

side connector terminals 9 and 10.

OK: Open circuit

Q: Is the check result normal?

YES :

Go to Step 6.

NO :

Repair the harness wires between
SRS-ECU connector B-35 (terminal No.9
and 10) and passenger’s (front) air bag
module connector B-06 (terminal No.1 and
2).

STEP 6. Check whether the diagnosis code is
reset.

Q: Is diagnosis code 24 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

).

AC206285

AF

B-35 (Y)

Connector: B-35

Harness side
connector
(rear view)

AC206286

Connector: B-06

2 1

Harness side
connector (front view)

B-06 (R)

AE

Glove box striker

AC006036

Section
A - A

B-35
Harness side connectors
(front view)

Cable tie

Short spring

4 mm or more

Terminal

AX

A

A

13 14 15 16 17 18 19 20

5 6 7 8 9 10 11 12

1 2

3 4

AC006044

B-35
Harness side connector
(rear view)

AS

Main

Index

Group

TOC

TROUBLESHOOTING

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-53

Code No.25: Passenger's (front) 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 sends 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 passenger’s (front) 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 passenger's (front) air bag

module (squib) circuit

• Improper connector contact

• Malfunction of the SRS-ECU

AC510225

CONNECTOR
LOCK SWITCH

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

SRS-ECU

CONNECTOR
LOCK SWITCH

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

NOTE

: CONNECTOR COUPLED: ON
CONNECTOR UNCOUPLED: OFF

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

AB

Main

Index

Group

TOC