Mitsubishi 380. Manual - part 793

SRS AIR BAG DIAGNOSIS

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-96

STEP 8. Check the harness wires for short circuit between
SRS-ECU connector D-26 (terminal No.57 and 58) and
side-airbag module (RH) connector D-32 (terminal No.1
and 2).
Q: Are the harness wires between SRS-ECU connector

D-26 (terminal No.57 and 58) and side-airbag module
(RH) connector D-32 (terminal No.1 and 2) in good
condition?
YES : Go to Step 9.
NO : Repair the harness wires between SRS-ECU

connector D-26 and side-airbag module (RH)
connector D-32. Then go to Step 9.

STEP 9. 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 B1420 set?

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

AC307779

D-32 (R)

HARNESS SIDE
CONNECTOR
(REAR VIEW)

CONNECTOR : D-32

24DB063A

CONNECTOR: D-26

SRS-ECU

5657

52 B A

D-26 (Y)

D-26 FLOOR

HARNESS

CONNECTOR

(REAR VIEW)

00DB076A

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827

SRS AIR BAG DIAGNOSIS

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-97

DTC B1421: Side-Airbag Module (RH) (Squib) System Fault 2 (Open in the Squib Circuit)

CAUTION

If DTC B1421 is set in the combination meter,
always diagnose the CAN bus lines.

CIRCUIT OPERATION

• The SRS-ECU judges how severe a collision is

by detecting signals from the left and right side
impact sensors. If the impact is over a predeter-
mined level, the SRS-ECU sends an ignition sig-
nal. At this time, if the side-airbag safing
G-sensor is on, the SRS side-airbag will inflate.

• The ignition signal is input to the side-airbag

module to inflate the side-airbag.

DTC SET CONDITIONS

This DTC is set if there is abnormal resistance
between the input terminals of the side-airbag mod-
ule (RH) (squib).

TROUBLESHOOTING HINTS

• Open circuit in the side-airbag module (RH)

(squib) circuit

• Improper connector contact

• Malfunction of the SRS-ECU

• Refer to circuit diagrams GROUP-

• Refer to configuration diagrams GROUP-

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 (Vehicles with CAN

communication system)

• MB991865: Dummy resistor

• MB991866: Resistor harness

24DB063A

CONNECTOR: D-26

SRS-ECU

5657

52 B A

D-26 (Y)

D-26 FLOOR

HARNESS

CONNECTOR

(REAR VIEW)

AC307779

D-32 (R)

CONNECTOR : D-32

SRS AIR BAG DIAGNOSIS

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-98

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

Q: Is the check result satisfactory?

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

Diagnosis ).

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 the DTC 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 Use Troubleshooting/Inspection
Service Points

− How to Cope with Intermittent

Malfunctions ).

00DB076A

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827

00DB076A

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827

SRS AIR BAG DIAGNOSIS

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-99

STEP 3. Check the side-airbag module (RH). (Using
diagnostic tool MB991958, read the diagnostic trouble
code.)
(1) Disconnect the negative battery terminal.
(2) Disconnect the side-airbag module (RH) connector D-32.

(3) Connect special tool MB991865 to special tool 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-32 harness side

connector by testprobe.

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

diagnostic trouble code.

Q: Is DTC B1421 set?

YES : Go to Step 4.
NO : Replace the seatback frame of the front seat (RH)

(Refer to GROUP 52A, Front Seat

P.52A-33

). Then

go to Step 5.

AC307779

D-32 (R)

HARNESS SIDE
CONNECTOR
(REAR VIEW)

CONNECTOR : D-32

AC006042BO

MB991866

(RESISTOR HARNESS)

D-32 HARNESS SIDE

CONNECTOR

D-32 SIDE-AIRBAG

MODULE (RH) CONNECTOR

MB991865 (DUMMY
RESISTOR: 3

Ω)

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