Mitsubishi 380. Manual - part 815

SRS AIR BAG DIAGNOSIS

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-184

STEP 3. Check the passenger's seat belt pre-tensioner. 
(Using diagnostic tool MB991958, read the diagnostic 
trouble code.)
(1) Disconnect the negative battery terminal.
(2) Disconnect passenger's seat belt pre-tensioner connector 

D-21. Use a flat-tipped screwdriver to unlock the locking 
button at the harness side connector by withdrawing it 
toward you in two stages, and then disconnect the 
connector.

(3) Connect special tool MB991865 to special tool MB991884.
(4) Connect special tool MB991884 to the D-21 harness side 

connector.

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

diagnostic trouble code.

Q: Is DTC B1471 set?

YES : Go to Step 4.
NO :  Replace the passenger's seat belt pre-tensioner 

(Refer to 

P.52B-250

). Then go to Step 5. 

AC306920AC

CONNECTOR: D-21

D-21 (B)

FOWARD

CENTER
PILLAR

HARNESS SIDE
CONNECTOR
(FRONT VIEW)

2 1

MB991884

MB991885

AC103283AO

MB991865
(DUMMY RESISTOR : 3Ω)

MB991884
(RESISTOR 
HARNESS)

D-21  HARNESS SIDE 
CONNECTOR

SRS AIR BAG DIAGNOSIS

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-185

STEP 4. Check the harness for open circuit between 
SRS-ECU connector D-27 (terminal No.7 and 8) and the 
passenger's seat belt pre-tensioner D-21 (terminal No.1 
and 2).
(1) Disconnect SRS-ECU connector D-27 and passenger's 

seat belt pre-tensioner connector D-21, and measure at the 
wiring harness side. For connector D-21, use a flat-tipped 
screwdriver to unlock the locking button at the harness side 
connector by withdrawing it toward you in two stages, and 
then disconnect the connector.

(2) Connect D-21 harness side connector to special tool 

MB991884.

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 the following terminals. It 

should be less than 2 ohms.

• SRS-ECU connector D-27 (terminal No.7) and the spe-

cial tool (terminal No.2)

• SRS-ECU connector D-27 (terminal No.8) and the spe-

cial tool (terminal No.1)

Q: Does continuity exist?

YES : Erase the diagnostic trouble code memory, and 

recheck if any DTC set. If DTC B1471 set, replace the 
SRS-ECU (Refer to 

P.52B-234

). Then go to Step 5.

NO :  Replace harness wires between SRS-ECU connector 

D-27 and passenger’s seat belt pre-tensioner 
connector D-21. Then go to Step 5.

AC306920AC

CONNECTOR: D-21

D-21 (B)

FOWARD

CENTER
PILLAR

HARNESS SIDE
CONNECTOR
(FRONT VIEW)

2 1

24DB064A

CONNECTOR: D-27

SRS-ECU

D-27 (Y)

A

B

18

10

15

7

13

5

14

6

16

8

17

9

19

11

20

12

1 2

3 4

D-27 Floor 

harness

connector

(rear view)

AC201287AT

D-21
HARNESS SIDE 
CONNECTOR

MB991884

24DB086A

2

1

A

B

18

10

15

7

13

5

14

6

16

8

17

9

19

11

20

12

1 2

3 4

<D-21 HARNESS SIDE

CONNECTOR>

SPECIAL TOOL

MB991884

(FRONT VIEW)

D-27 FLOOR

HARNESS SIDE

CONNECTOR

(REAR VIEW)

SRS AIR BAG DIAGNOSIS

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-186

STEP 5. Check for diagnostic trouble code.
Check again if the DTC is set.
(1) Erase the DTC.
(2) Turn the ignition switch to the "ON" position.
(3) Check if the DTC is set.
(4) Turn the ignition switch to the "LOCK" (OFF) position.

Q: Is DTC B1471 set?

YES : Return to Step 1. 
NO :  The procedure is complete.

00DB076A

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827

SRS AIR BAG DIAGNOSIS

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-187

DTC B1472: Seat Belt Pre-Tensioner (LH) (Squib) System Fault for Power Supply Circuit (Short-Circuit 
to Power Supply)

CAUTION

If DTC B1472 is set in the SRS-ECU, always diag-
nose the CAN main bus line.

.

CIRCUIT OPERATION

The SRS-ECU judges how severe a collision is by 
detecting signals from the front impact sensors and 
the front air bag analog 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. 

.

DTC SET CONDITIONS

This DTC is set if there is abnormal resistance 
between the input terminals of the passenger's seat 
belt pre-tensioner (squib).

.

TROUBLESHOOTING HITS

• Damaged wiring harnesses or connectors

• Short to the power supply in the passenger's seat 

belt pre-tensioner (squib) harness

• Malfunction of the SRS-ECU

• Refer to circuit diagrams GROUP-

90

• Refer to configuration diagrams GROUP-

80

.

24DB064A

CONNECTOR: D-27

SRS-ECU

D-27 (Y)

A

B

18

10

15

7

13

5

14

6

16

8

17

9

19

11

20

12

1 2

3 4

D-27 Floor 

harness

connector

(rear view)

AC306920AB

CONNECTOR: D-21

D-21 (B)

FOWARD

CENTER
PILLAR