Mitsubishi Grandis. Manual - part 1009

TROUBLESHOOTING

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-88

YES : 

Go to Step 2

NO : 

Repair the CAN bus lines (Refer to GROUP 
54D, Diagnosis-Can Bus Diagnostic Chart 

P.54D-16

). 

STEP 2. Check whether the diagnosis code is 
reset.

Check again if the diagnosis code is set.
(1) Erase the diagnosis code.
(2) Ignition: LOCK (OFF) position to ON
(3) On completion, check that the diagnosis code is 

not reset.

Q: Is the diagnosis code set?

YES : 

Go to Step 3.

NO : 

There is an intermittent malfunction such as 
poor engaged connector(s) or open circuit 
(Refer to GROUP 00, How to Cope with 
Intermittent Malfunction 

P.00-5

).

STEP 3. Check the side-airbag module (LH). 
(MUT-III diagnosis code.)
(1) Disconnect the negative battery terminal.

(2) Disconnect the side-airbag module (LH) 

connector D-22.

(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 D-22 

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 B1433 set?

YES : 

Go to Step 4.

NO : 

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

P.52A-24

).

STEP 4. Check the side-airbag module (RH) 
circuit. Voltage measurement at the SRS-ECU 
connector C-120.

(1) Disconnect SRS-ECU connector C-120.

DANGER

To prevent the air bag from deploying 
unintentionally, disconnect the side-airbag 
module (LH) connector D-22 to short the 
squib circuit.

(2) Disconnect left hand side-airbag module (LH) 

connector D-22.

AC303521

AD

D-22 (R)

Connector: D-22

Harness side
(front view)

AC006042 BY

MB991866
(Resistor harness)

D-22 Harness side
connector

D-22 Side-airbag
module (LH) connector

MB991865 (Dummy
resistor: 3

 

Ω)

AC311438 AE

C-120 (Y)

Connector: C-120

Harness side
(front view)

AC303521

AD

D-22 (R)

Connector: D-22

Harness side
(front view)

TROUBLESHOOTING

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-89

(3) Turn the ignition switch to the "ON" position.

CAUTION

Do not insert a test probe into the terminal from 
its front side directly, as the connector contact 
pressure may be weakened.
(4) Measure the voltage between C-120 harness 

side connector terminals 9, 10 and body earth.

OK: 0 V

Q: Is the check result normal? 

YES : 

Go to Step 5.

NO : 

Repair the harness wires between 
SRS-ECU connector C-120 (terminal No.9 
and 10) and side-airbag module (LH) 
connector D-22 (terminal No.1 and 2).

STEP 5. Check whether the diagnosis code is 
reset.

Q: Is diagnosis code B1433 set?

YES : 

Replace the SRS-ECU (Refer to 

P.52B-223

).

NO : 

An intermittent malfunction is suspected 
(Refer to GROUP 00, How to Use 
Troubleshooting/Inspection Service Points 

P.00-5

). 

Code No.B1437: Side Impact Sensor (LH) Power Supply Circuit System

AC308177

A

B

18

10

15

7

13

5

14

6

16

8

17

9

19

11

20

12

1 2

3 4

C-120 Harness side
connector (rear view)

AD

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

SIDE IMPACT 
SENSOR (FRONT: LH)

SRS-ECU

Side Impact Sensor (Front) (LH) Circuit

TROUBLESHOOTING

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-90

CAUTION

If diagnosis code B1437 is set in the SRS-ECU, 
always diagnose the CAN main bus line.

OPERATION

The side impact sensor includes an analogue G 
sensor and CPU, etc. The CPU monitors the 
analogue G sensor output signal. If the CPU judges 
that the side-airbags and curtain air bags should be 
deployed, it sends a fire signal to the SRS-ECU to 
deploy the side-airbags and curtain air bags. In 
addition, the CPU diagnoses the internal 
components of the side impact sensor. If a 
malfunction occurs, it requests the SRS-ECU to set a 
diagnosis code.

DIAGNOSIS CODE SET CONDITIONS

This diagnosis code is set if the power supply voltage 
of the side impact sensor (LH) drops below the rated 
value for a continuous period of 5 seconds or more. 
However, diagnosis code B1437 will be automatically 
cleared and the SRS warning lamp will switch off if 
the condition returns to normal. 

TROUBLESHOOTING HINTS

• Damaged wiring harnesses or connectors

• Malfunction of the side impact sensor (LH)

• Malfunction of the SRS-ECU

PROBABLE CAUSES

STEP 1. MUT-III CAN bus diagnostics

Use the MUT-III to diagnose the CAN bus lines.

Q: Is the check result normal?

YES : 

Go to Step 2.

NO : 

Repair the CAN bus line (Refer to GROUP 
54D, Diagnosis 

P.54D-16

).

STEP 2. Check whether the diagnosis code is 
reset.

Check again if the diagnosis code is set.
(1) Erase the diagnosis code.
(2) Ignition: LOCK (OFF) position to ON
(3) On completion, check that the diagnosis code is 

not reset.

Q: Is the diagnosis code set?

YES : 

Go to Step 3.

NO : 

There is an intermittent malfunction such as 
poor engaged connector(s) or open circuit 
(Refer to GROUP 00, How to Cope with 
Intermittent Malfunction 

P.00-5

).

STEP 3. Check the side impact sensor (LH) 
power supply circuit. Voltage measurement at the 
side impact sensor (LH) connector D-18.
(1) Disconnect the negative battery terminal.

(2) Disconnect side impact sensor (LH) connector 

D-18,, and measure at the wiring harness side.

(3) Connect the negative battery terminal.
(4) Turn the ignition switch to the "ON" position.

CAUTION

Do not insert a test probe into the terminal from 
its front side directly, as the connector contact 
pressure may be weakened.
(5) Measure the voltage between the D-18 harness 

side connector terminal 1 and body earth.

OK: 9 V or more

Q: Is the check result normal?

YES : 

Replace the side impact sensor (LH) (Refer 

to 

P.52B-236

). Then go to Step 5.

NO : 

Go to Step 4.

AC302579AC

D-18 (Y)

Connector: D-18

Centre
pillar

Front vehicle

Harness side
(front view)

AC311097

D-18 Harness side
connector
(rear view)

AI

TROUBLESHOOTING

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-91

STEP 4. Check the harness wires for open circuit 
or short circuit between SRS-ECU connector 
C-120 (terminal No.19 and 20) and side impact 
sensor (LH) connector D-18 (terminal No.1 and 
2).

Q: Are the harness wires between SRS-ECU 

connector C-120 (terminal No.19 and 20) and side 

impact sensor (LH) connector D-18 (terminal No.1 
and 2) in good condition?

YES : 

Go to Step 5.

NO : 

Replace the harness wires between 
SRS-ECU connector C-120 (terminal No.19 
and 20) and side impact sensor (LH) 
connector D-18 (terminal No.1 and 2).

STEP 5. Check whether the diagnosis code is 
reset.

Q: Is diagnosis code B1437 set?

YES : 

Replace the SRS-ECU (Refer to 

P.52B-223

).

NO : 

An intermittent malfunction is suspected 
(Refer to GROUP 00, How to Use 
Troubleshooting/Inspection Service Points 

P.00-5

).

AC311438 AE

C-120 (Y)

Connector: C-120

Harness side
(front view)

AC302579AC

D-18 (Y)

Connector: D-18

Centre
pillar

Front vehicle

Harness side
(front view)