Mitsubishi L200. Manual — part 590

TROUBLESHOOTING

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-31

Code No.B1403: Driver's air bag module (squib) system (short-circuited to the power supply)

AC806117

Driver's Air Bag Module (Squib) Circuit

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

CONNECTOR
LOCK SWITCH

CONNECTOR
LOCK SWITCH

CLOCK SPRING

SRS-ECU

CONNECTOR
LOCK SWITCH

NOTE

: CONNECTOR COUPLED: ON
CONNECTOR UNCOUPLED: OFF

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 PU : Purple

AB

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

via the clock spring to inflate the air bag.

DIAGNOSIS CODE SET CONDITIONS
This diagnosis code is set if the driver’s air bag squib
wire(s) are short-circuited to the power supply.

PROBABLE CAUSES

• Malfunction of the clock spring

• Damaged harness wires and connectors

• Short to the power supply in the driver's air bag

module (squib) 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.

AC501669

A

C-303 Air bag
module connector

AB

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

module connector C-303 in arrow direction,

TROUBLESHOOTING

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-32

disconnect the connector.

AC303006AF

C-303 Air bag

module

connector

MB991865

(Dummy

resistor : 3 )

MB991866
(Resistor 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) Insert special tool (MB991866) into clock spring

side air bag module connector C-303 by
backprobing.

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

diagnosis code.

Q: Is diagnosis code B1403 out put?

YES :

Go to Step 2.

NO :

Replace the driver’s air bag module (Refer
to

P.52B-268

).

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

AC903858AD

Connector: C-305 <LHD>

Harness side
connector
(front view)

C-305 (Y)

AC903869AD

Connector: C-305 <RHD>

Harness side
connector
(front view)

C-305 (Y)

C-305

(2) Disconnect the clock spring connector C-305.

AC303587AN

C-305 Clock spring

connector

MB991865
(Dummy resistor: 3 )

MB991866

(Resistor harness)

(Rear view)

(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-305 (terminal No.3 and
4) by backprobing.

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

diagnosis code.

Q: Is diagnosis code B1403 set?

YES :

Go to Step 3.

NO :

Replace the clock spring (Refer to

P.52B-

268

).

TROUBLESHOOTING

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-33

STEP 3. Voltage measurement at the SRS-ECU
connector C-131.
(1) Disconnect the negative battery terminal.

AC501670

AB

C-131 (Y)

Connector: C-131

Harness side
connector
(rear view)

(2) Disconnect SRS-ECU connector C-131.

AC903858AD

Connector: C-305 <LHD>

Harness side
connector
(front view)

C-305 (Y)

AC903869AD

Connector: C-305 <RHD>

Harness side
connector
(front view)

C-305 (Y)

C-305

DANGER

To prevents the air bag from deploying unin-
tentionally, disconnect the clock spring con-
nector C-305 to short the squib circuit.

(3) Disconnect the clock spring connector C-305.

AC100391

Section
A - A

C-131 Harness side connectors
(front view)

Cable tie

Short spring

4 mm or more

Terminal

A

BE

A

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

between terminals 11, 12 and the short spring to
release the short spring.

(5) Connect the negative battery terminal.
(6) Turn the ignition switch to the "ON" position.

AC006255

13 14 15 16 17 18 19 20

5 6 7 8 9 10 11 12

1 2

3 4

AX

C-131 Harness side
connector (rear view)

CAUTION

Do not insert a test probe into the terminal from
its front side directly as the connector contact
pressure may be weakened.
(7) Voltage measurement between C-131 harness

side connector terminals 11, 12 and body earth.

OK: 1 V or less

Q: Is the check result normal?

YES :

Go to Step 4.

NO :

Repair the harness wires between SRS-
ECU connector C-131 (terminal No.11 and
12) and clock spring connector C-305
(terminal No.3 and 4).

STEP 4. Check whether the diagnosis code is
reset.

Q: Is diagnosis code B1403 set?

TROUBLESHOOTING

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-34

YES :

Replace the SRS-ECU (Refer to

P.52B-

266

).

NO :

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

Code No.B1404: Driver's air bag module (squib ignition drive circuit) system detected short circuit

Code No.B1405: Driver's air bag module (squib ignition drive circuit) system detected open circuit

Code No.B1414: Passenger’s (front) air bag module (squib ignition drive circuit) system detected
short circuit

Code No.B1415: Passenger’s (front) air bag module (squib ignition drive circuit) system detected
open circuit

Code No.B1466: Analogue G-sensor system in the SRS-ECU

Code No.B1467: Safing G-sensor open circuit

Code No.B1468: Safing G-sensor short circuit

Code No.B1478: SRS-ECU capacitor circuit voltage too high

Code No.B1479: SRS-ECU capacitor circuit voltage too low

Code No.B1496: SRS-ECU non-volatile memory (EEPROM)

Code No.B1497: SRS-ECU application specific integrated circuit (for frontal activation)

Code No.B1498: SRS-ECU ROM or RAM

Code No.B1499: Collision decision

Code No.B1550: SRS warning lamp drive circuit malfunction

Code No.B1557: SRS-ECU application specific integrated circuit

Code No.B1607: Seat belt pre-tensioner (driver's side) (squib ignition drive circuit) system detected
short circuit

Code No.B1608: Seat belt pre-tensioner (driver's side) (squib ignition drive circuit) system detected
open circuit

Code No.B1613: Seat belt pre-tensioner (passenger’s side) (squib ignition drive circuit) system
detected short circuit

Code No.B1614: Seat belt pre-tensioner (passenger’s side) (squib ignition drive circuit) system
detected open circuit

DIAGNOSIS CODE SET CONDITIONS
These diagnosis code are set when a fault is
detected in the SRS-ECU. The most likely causes for
this code to be set are shown in the table below:

Code No.

Part/Circuit integral to SRS-
ECU

Trouble causes

B1404

Driver's air bag module (squib
ignition drive circuit)

• Short circuit in the squib ignition drive circuit

B1405

• Open circuit in the squib ignition drive circuit

B1414

Passenger's (front) air bag
module (squib ignition drive
circuit)

• Short circuit in the squib ignition drive circuit

B1415

• Open circuit in the squib ignition drive circuit

B1466

Analogue G-sensor

• When the analogue G-sensor is not operating

• When the characteristics of the analogue G-sensor

are abnormal

• When the output from the analogue G-sensor is

abnormal