Mitsubishi Montero (2004+). Manual - part 1205

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-155

DTC 72: Right Hand Side-Airbag Module (Squib) System Fault 2 (Open in the Squib Circuit)

.

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 outputs an ignition 
signal. 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

MICROCOMPUTER

AIR BAG DRIVE CIRCUIT

SRS-ECU

CONNECTOR
LOCK SWITCH

CONNECTOR
LOCK SWITCH

SIDE AIR BAG
MODULE (SQUIB)
(RH)

NOTE

: CONNECTOR
  COUPLED: ON
  CONNECTOR
  UNCOUPLED: OFF

Side-Airbag Module (RH) (Squib) Circuit

ACX01478AI

CONNECTOR: E-07

E-07 (Y)

ACX01649

X0942CA

AD

CONNECTOR: F-21

F-21 (R)

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-156

.

DIAGNOSIS

Required Special Tools:

• MB991958: Scan Tool (MUT-III Sub Assembly)

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

• MB991827: MUT-III USB Cable

• MB991911: MUT-III Main Harness B (Vehicles without 

CAN communication system)

• MB991865: Dummy resister

• MB991866: Resister harness

STEP 1. Check the side-airbag module (RH). (Using scan 
tool MB991958, read the diagnostic trouble code).
(1) Disconnect the negative battery terminal.
(2) Disconnect the side-airbag module (RH) connector F-21.

(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 harness connector by 

backprobing.

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

diagnostic trouble code. 

Q: Is DTC 72 set?

YES : Go to Step 2.
NO :  Replace the seat back assembly of the front seat 

(RH) (Refer to GROUP 52A, Front Seat 

P.52A-14

). 

Then go to Step 3.

ACX01649

X0942CA

AF

CONNECTOR: F-21

F-21 (R)

1 2

HARNESS SIDE 
CONNECTOR
(REAR VIEW)

AC006042 AW

MB991866
(RESISTOR HARNESS)

F-21 HARNESS 
CONNECTOR

F-21 SIDE-AIRBAG 
MODULE (RH) CONNECTOR

MB991865 (DUMMY 
RESISTOR: 3 

Ω)

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-157

STEP 2. Check the harness for open circuit between 
SRS-ECU connector E-08 (terminal No.23 and 24) and the 
side-air bag module (RH) connector F-21 (terminal No.1 
and 2).
(1) Disconnect SRS-ECU connector E-07 and side-air bag 

module (RH) connector F-21.

CAUTION

Do not insert a test probe into the terminal from its front 
side directly as the connector contact pressure may be 
weakened.
(2) Check for continuity between the following terminals.

• Between connector E-07 terminal 23 and connector 

F-21 terminal 2.

• Between connector E-07 terminal 24 and connector 

F-21 terminal 1.

(3) It should be less than 2 ohms.
Q: Does continuity exist?

YES : Erase the diagnostic trouble code memory, and check 

the diagnostic trouble code. If DTC 72 sets, replace 
the SRS-ECU (Refer to 

P.52B-215

). Then go to Step 

3.

NO :  Repair the harness wires between SRS-ECU 

connector E-07 and side-airbag module (RH) 
connector F-21. Then go to Step 3.

STEP 3. Recheck for diagnostic trouble code. 
Q: Is DTC 72 set?

YES : Return to Step 1. 
NO :  The procedure is complete. (If no malfunctions are not 

found in all steps, an intermittent malfunction is 
suspected. Refer to GROUP 00, How to Use 
Troubleshooting/Inspection Service Points 

− How to 

Cope with Intermittent Malfunction 

P.00-6

).

ACX01478AJ

CONNECTOR: E-07

E-07 (Y)

34 35 36 37 38 39 40 41 42

25 26 27 28 29 30 31 32 33

21 22

23 24

HARNESS SIDE
CONNECTOR
(REAR VIEW)

ACX01649

X0942CA

AF

CONNECTOR: F-21

F-21 (R)

1 2

HARNESS SIDE 
CONNECTOR
(REAR VIEW)

34 35 36 37 38 39 40 41 42

25 26 27 28 29 30 31 32 33

21 22

23 24

1 2

AC100382

E-07 HARNESS SIDE
CONNECTOR 
(REAR VIEW)

F-21 HARNESS SIDE
CONNECTOR (REAR VIEW)

AO

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-158

DTC 75: Right Hand Side-Airbag Module (Squib) System Fault Power Supply Circuit (Short-Circuit to 
Power Supply)

.

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 outputs an ignition 
signal. 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 air bag.

.

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

.

MICROCOMPUTER

AIR BAG DRIVE CIRCUIT

SRS-ECU

CONNECTOR
LOCK SWITCH

CONNECTOR
LOCK SWITCH

SIDE AIR BAG
MODULE (SQUIB)
(RH)

NOTE

: CONNECTOR
  COUPLED: ON
  CONNECTOR
  UNCOUPLED: OFF

Side-Airbag Module (RH) (Squib) Circuit

ACX01478AI

CONNECTOR: E-07

E-07 (Y)

ACX01649

X0942CA

AD

CONNECTOR: F-21

F-21 (R)