Mitsubishi 380. Manual - part 816

SRS AIR BAG DIAGNOSIS

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-188

DIAGNOSIS

Required Special Tools:

• MB991958: diagnostic tool (MUT-III Sub Assembly)

• MB991824: Vehicle Communication Interface (V.C.I.)

• MB991827: MUT-III USB Cable

• MB991910: MUT-III Main Harness A

• MB991865: Dummy resistor

• MB991884: Resistor harness (For Pre-tensioner)

STEP 1. Using diagnostic tool MB991958, diagnose the 
CAN bus line.

CAUTION

To prevent damage to diagnostic tool MB991958, always 
turn the ignition switch to the "LOCK" (OFF) position 
before connecting or disconnecting diagnostic tool 
MB991958.
(1) Connect diagnostic tool MB991958. Refer to "How to 

connect the diagnostic tool 

P.52B-19

."

(2) Turn the ignition switch to the "ON" position.
(3) Diagnose the CAN bus line.
(4) Turn the ignition switch to the "LOCK" (OFF) position.

Q: Is the CAN bus line found to be normal?

YES : Go to Step 2.
NO :  Repair the CAN bus line (Refer to GROUP 54C, 

Diagnosis ).

00DB076A

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827

SRS AIR BAG DIAGNOSIS

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-189

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

Q: Is DTC B1472 set?

YES : Go to Step 3.
NO :  Go to Step 6.

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 check the 

diagnostic trouble code.

Q: Is DTC B1472 set?

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

(Refer to 

P.52B-250

). Then go to Step 6.

00DB076A

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827

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-190

STEP 4. Check the passenger's seat belt pre-tensioner 
circuit. Measure the voltage at the SRS-ECU connector 
D-27.
(1) Disconnect SRS-ECU connector D-27.

(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) 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 D-27 harness side connector 

terminals 7, 8 and body ground.
Voltage should measure 0 volt.

Q: Is the measured voltage within the specified range?

YES : Erase the diagnostic trouble code memory, and check 

the diagnostic trouble code. If DTC B1472 sets, 
replace the SRS-ECU (Refer to 

P.52B-77

). Then go 

to Step 6.

NO :  Go to Step 5.

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)

AC306920AC

CONNECTOR: D-21

D-21 (B)

FOWARD

CENTER
PILLAR

HARNESS SIDE
CONNECTOR
(FRONT VIEW)

2 1

24DB087A

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 

SIDE CONNECTOR

(REAR VIEW)

SRS AIR BAG DIAGNOSIS

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-191

STEP 5. Check the harness wires for short circuit to power 
supply between SRS-ECU connector D-27 (terminal No.7 
and 8) and passenger's seat belt pre-tensioner connector 
D-21 (terminal No.1 and 2).
Q: Are the harness wires between SRS-ECU connector 

D-27 (terminal No.7 and 8). and passenger's seat belt 
pre-tensioner connector D-21 (terminal No.1 and 2) in 
good condition?
YES : Go to Step 6.
NO :  Replace the harness wires between SRS-ECU 

connector D-27 and passenger's seat belt 
pre-tensioner connector D-21. Then go to Step 6.

STEP 6. Recheck 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 B1472 set?

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

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)

00DB076A

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827