Content .. 567 568 569 570 ..

Mitsubishi Colt Ralliart. Manual - part 569

TROUBLESHOOTING

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-114

Q: Is the check result normal?

YES :

Go to Step 3.

NO :

Repair the harness wires between
SRS-ECU connector B-34 (terminal No.23
and 24) and side-airbag module (RH)
connector C-25 (terminal No.1 and 2).

STEP 3. Check whether the diagnosis code is
reset.

Q: Is diagnosis code 76 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.79: Side impact sensor (LH) communication error

Code No.93: Side impact sensor (LH) communication impossible

OPERATION

The side impact sensor (front) includes an analogue
G-sensor and CPU, etc. The CPU monitors the ana-
logue G-sensor output signal. If the CPU judges that
the side-airbags should be deployed, it sends a fire
signal to the SRS-ECU to deploy the side-airbags.
Besides that, the CPU diagnoses the internal compo-
nents of the side impact sensor. If a malfunction
occurs, it requests the SRS-ECU to set a diagnosis
code.

DIAGNOSIS CODE SET CONDITIONS

These diagnosis codes are set if communication
between the side impact sensor (LH) and the
SRS-ECU is not possible or communication is faulty.

PROBABLE CAUSES

• Damaged wiring harnesses or connectors

• Malfunction of the side impact sensor (LH)

• Malfunction of the SRS-ECU

AC510245

SRS-ECU

CONSTANT
VOLTAGE CIRCUIT

ANALOGUE
G SENSOR

EEP ROM

SIDE IMPACT
SENSOR (LH)

MICRO COMPUTER

INTERFACE
CIRCUIT

CPU

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

Side Impact Sensor (LH) Power Supply Circuit

Main

Index

Group

TOC

TROUBLESHOOTING

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-115

DIAGNOSIS PROCEDURE

STEP 1. Check the side impact sensor (LH).
(M.U.T.-III diagnosis code)
(1) Disconnect the negative battery terminal.
(2) Temporarily replace the side impact sensor (LH)

with the side impact sensor (RH).

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

diagnosis code.

Q: Is diagnosis code 89 or 96 set?

YES :

Replace the side impact sensor (LH) with a

new one (Refer to

P.52B-157

NO :

Go to Step 2.

STEP 2. Check the harness wires for open circuit
or short circuit between SRS-ECU connector
B-34 (terminal No.34 and 36) and side impact
sensor (LH) (front) connector C-21 (terminal No.1
and 2).

Q: Is the check result normal?

YES :

Go to Step 3.

NO :

Repair the harness wires between
SRS-ECU connector B-34 (terminal No.34
and 36) and side impact sensor (LH)
connector C-21 (terminal No.1 and 2).

STEP 3. Check whether the diagnosis code is
reset.

Q: Is diagnosis code 79 or 93 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

B-34 (Y)

Connector: B-34

Harness side
connector
(rear view)

343536373839404142

252627282930313233

2122

2324

AC401059

Connector: C-21

C-21 (Y)

Harness side
(front view)

Main

Index

Group

TOC

TROUBLESHOOTING

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-116

Code No.81: Side-airbag module (squib) (LH) system (short-circuited between terminals of the squib
circuit)

OPERATION

• The SRS-ECU judges how severe a collision is

by detecting signals from the left and right side
impact sensors. If the impact is over a predeter-
mined level, the SRS-ECU sends an ignition sig-
nal. At this time, if the side-airbag safing
G-sensor is on, the SRS side-airbag will inflate.

• The ignition signal is input to the side-airbag

module to inflate the side-airbag.

DIAGNOSIS CODE SET CONDITIONS

This diagnosis code is set if one side-airbag squib
(LH) wire shorted to the other. However, if no diagno-
sis 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 side-airbag module

(LH) (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 disconnected).
(Refer to

P.52B-3

). Therefore, if connector B-34 or

C-23 is damaged 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.

AC510246

AIR BAG DRIVE
CIRCUIT

MICRO COMPUTER

SRS-ECU

SIDE-AIRBAG
MODULE
(SQUIB)
(LH)

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

CONNECTOR
LOCK
SWITCH

Side-airbag Module (LH) (Squib) Circuit

Main

Index

Group

TOC

TROUBLESHOOTING

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-117

STEP 2. Connector lock check: SRS-ECU
connector B-34 (M.U.T.-III diagnosis code)
(1) Disconnect the negative battery terminal.

(2) Disconnect connectors B-34 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 81 out put?

YES :

Go to Step 3.

NO :

The procedure is complete. It is assumed
that diagnosis code 81 set as connector
B-34 was engaged improperly.

STEP 3. Connector lock check: SRS-ECU
connector B-34 and side-airbag module (LH)
connector C-23 (M.U.T.-III diagnosis code)
(1) Disconnect the negative battery terminal.

(2) Disconnect connectors B-34 and C-23 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 81 out put?

YES :

Go to Step 4.

NO :

The procedure is complete. It is assumed
that diagnosis code 81 set as connector
B-34 or C-23 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) Disconnect the side-airbag module (LH)

connector C-23.

(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 the C-23

harness side connector by backprobing.

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

diagnosis code.

Q: Is diagnosis code 81 set?

YES :

Go to Step 5.

NO :

Replace the frame assembly of the front
seat (LH) (Refer to GROUP 52A, Front Seat

P.52A-23

AC206285

B-34 (Y)

Connector: B-34

Harness side
connector
(rear view)

343536373839404142

252627282930313233

2122

2324

AC206285

B-34 (Y)

Connector: B-34

Harness side
connector
(rear view)

343536373839404142

252627282930313233

2122

2324

AC401575

Connector: C-23

C-23 (R)

2 1

Harness side
connector
(front view)

AC401575

Connector: C-23

C-23 (R)

2 1

Harness side
connector
(front view)

AC006042 CM

MB991866
(Resistor harness)

C-23

Intermediate h

arness side

connector

MB991865 (Dummy
resistor: 3

Ω)

C-23 Side-airbag
module (LH) connector

Main

Index

Group

TOC

Content .. 567 568 569 570 ..