Mitsubishi Grandis. Manual - part 1025

TROUBLESHOOTING

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-152

Code No.B1472: Seat Belt Pre-Tensioner (LH) (Squib) System Fault for Earth Circuit (Short-Circuited 
to Earth)

CAUTION

If diagnosis code B1472 is set in the SRS-ECU, 
always diagnose the CAN main bus line.

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 pre-tensioner will deploy. 

DIAGNOSIS CODE SET CONDITIONS

This diagnosis code is set if there is abnormal 
resistance between the input terminals of the seat 
belt pre-tensioner (LH) (squib).

PROBABLE CAUSES

• Damaged wiring harnesses or connectors

• Short to the earth in the seat belt pre-tensioner 

(LH) (squib) harness

• Malfunction of the SRS-ECU

DIAGNOSIS PROCEDURE

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

).

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

SEAT BELT
PRETENSIONER
(LH)

SRS-ECU

CONNECTOR
LOCK SWITCH

CONNECTOR
LOCK SWITCH

: CONNECTOR
  CONNECTED: ON
  CONNECTOR
  DISCONNECTED: OFF

NOTE

Seat Belt Pre-Tensioner (LH) (Squib) Circuit

TROUBLESHOOTING

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-153

STEP 3. Check the seat belt pre-tensioner (LH). 
(MUT-III diagnosis code.)
(1) Disconnect the negative battery terminal.

(2) Disconnect seat belt pre-tensioner (LH) 

connector D-19. Use a flat-tipped screwdriver to 
unlock the locking button at the harness side 
connector by with drawing it toward you in two 
stages, and then disconnect the connector.

(3) Connect special tool dummy resistor (MB991865) 

to special tool resistor harness (MB991884).

(4) Connect special tool MB991884 to the D-24 

harness side connector.

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

diagnosis code.

Q: Is diagnosis code B1472 set?

YES : 

Go to Step 4.

NO : 

Replace the seat belt pre-tensioner (LH). 
Refer to 

P.52B-239

.

STEP 4. Check the driver's seat belt 
pre-tensioner circuit. Resistance measurement at 
the SRS-ECU connector C-120.

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

(2) Disconnect seat belt pre-tensioner (LH) 

connector D-19. Use a flat-tipped screwdriver to 
unlock the locking button at the harness side 
connector by with drawing it toward you in two 

AC302393AC

 D-19 (B)

Connector: D-19

Centre
pillar

Front vehicle

Harness side
(front view)

AC103556 AY

Locking button

Flat-tip screw
driver

D-19 Harness
side connector

D-19 Seat belt
pre-tensioner (LH)
connector

MB991884
MB991885

AC103283AV

MB991865
(Dummy resistor : 3

Ω)

MB991884
(Resistor
harness)

D-19  Harness side
connector

AC311438 AE

C-120 (Y)

Connector: C-120

Harness side
(front view)

AC302393AC

 D-19 (B)

Connector: D-19

Centre
pillar

Front vehicle

Harness side
(front view)

AC103556 AY

Locking button

Flat-tip screw
driver

D-19 Harness
side connector

D-19 Seat belt
pre-tensioner (LH)
connector

TROUBLESHOOTING

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-154

stages, and then disconnect the connector.

CAUTION

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

connector terminals 7, 8 and body earth.

OK: Open circuit

Q: Is the check result normal?

YES : 

Go to Step 5.

NO : 

Repair the harness wires between 
SRS-ECU connector C-120 (terminal No.7 
and 8) and seat belt pre-tensioner (LH) 
connector D-19 (terminal No.1 and 2).

STEP 5. Check whether the diagnosis code is 
reset.

Q: Is diagnosis code B1472 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.B1473: Seat Belt Pre-Tensioner (LH) (Squib) System Fault for Power Supply Circuit 
(Short-Circuit to Power Supply)

AC308182

A

B

18

10

15

7

13

5

14

6

16

8

17

9

19

11

20

12

1 2

3 4

AD

C-120 Harness side
connector
(rear view)

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

SEAT BELT
PRETENSIONER
(LH)

SRS-ECU

CONNECTOR
LOCK SWITCH

CONNECTOR
LOCK SWITCH

: CONNECTOR
  CONNECTED: ON
  CONNECTOR
  DISCONNECTED: OFF

NOTE

Seat Belt Pre-Tensioner (LH) (Squib) Circuit

TROUBLESHOOTING

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-155

CAUTION

If diagnosis code B1473 is set in the SRS-ECU, 
always diagnose the CAN main bus line.

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 pre-tensioner will deploy. 

DIAGNOSIS CODE SET CONDITIONS

This diagnosis code is set if there is abnormal 
resistance between the input terminals of the seat 
belt pre-tensioner (LH) (squib).

TROUBLESHOOTING HITS

• Damaged wiring harnesses or connectors

• Short to the power supply in the seat belt 

pre-tensioner (LH) (squib) harness

• Malfunction of the SRS-ECU

DIAGNOSIS PROCEDURE

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 : 

Go to Step 5.

STEP 3. Check the seat belt pre-tensioner (LH). 
(MUT-III diagnosis code.)
(1) Disconnect the negative battery terminal.

(2) Disconnect seat belt pre-tensioner (LH) 

connector D-19. Use a flat-tipped screwdriver to 
unlock the locking button at the harness side 
connector by with drawing it toward you in two 
stages, and then disconnect the connector.

(3) Connect special tool dummy resistor (MB991865) 

to special tool resistor harness (MB991884).

(4) Connect special tool MB991884 to the D-19 

harness side connector.

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

diagnosis code.

Q: Is diagnosis code B1473 set?

YES : 

Go to Step 4.

NO : 

Replace the seat belt pre-tensioner (LH). 
(Refer to 

P.52B-239

).

AC302393AC

 D-19 (B)

Connector: D-19

Centre
pillar

Front vehicle

Harness side
(front view)

AC103556 AY

Locking button

Flat-tip screw
driver

D-19 Harness
side connector

D-19 Seat belt
pre-tensioner (LH)
connector

MB991884
MB991885

AC103283AV

MB991865
(Dummy resistor : 3

Ω)

MB991884
(Resistor
harness)

D-19  Harness side
connector