Mitsubishi Montero (2004+). Manual — part 1178

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-47

DTC 22: Driver's Air Bag Module (Squib) System Fault 2 (Open in the Squib Circuit)

.

AIR BAG MODULE
(SQUIB)
(DRIVER'S SIDE)

CLOCK
SPRING

MICROCOMPUTER

AIR BAG DRIVE CIRCUIT

SRS-ECU

CONNECTOR
LOCK SWITCH

CONNECTOR
LOCK SWITCH

CONNECTOR
LOCK SWITCH

NOTE

: CONNECTOR
COUPLED: ON
CONNECTOR
UNCOUPLED: OFF

Driver's Air Bag Module (Squib) Circuit

AC204226AD

CLOCK SPRING

D-206 (Y)

CONNECTORS: D-206, D-229

D-229

ACX01478 AG

CONNECTOR: E-08

E-08 (Y)

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-48

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 outputs an ignition signal. At this time,
if the front air bag safing G-sensor is on, the SRS
air bag will inflate.

• The ignition signal is input to the air bag module

via the clock spring to inflate the air bag.

.

DTC SET CONDITIONS
This DTC is set if there is abnormal resistance

between the input terminals of the driver's side air
bag module (squib). The most likely causes for
this code to be set are the followings:

• Open circuit in the driver's air bag module

(squib) or harness

• Open circuit in the clock spring

• Malfunction of connector contact

However, if no DTC resets, the SRS warning light will
be switched off (DTC will be retained).

.

TROUBLESHOOTING HINTS

• Open circuit in the clock spring

• Open circuit due to improper neutral position of

the clock spring

• Open circuit in the driver's air bag module (squib)

circuit

• Disengaged driver's air bag module (squib) con-

nector

• Improper connector contact

• Malfunction of the SRS-ECU

.

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

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-49

STEP 1. Check the driver's air bag module. (Using scan
tool MB991958, read the diagnostic trouble code).
(1) Disconnect the negative battery terminal.
(2) By sliding the A section (in the figure) of air bag module

connector D-229 in the arrow direction, disconnect the
connector.

(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 clock spring side air bag

module connector D-229 by backprobing.

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

diagnostic trouble code.

Q: Is DTC 22 set?

YES : Go to Step 2.
NO : Replace the driver's air bag module (Refer to

P.52B-217

). Then go to Step 4.

STEP 2. Check the clock spring. (Using scan tool
MB991958, read the diagnostic trouble code).
(1) Disconnect the negative battery terminal.
(2) Disconnect clock spring connector D-206.
(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 clock spring harness

connector D-206 (terminal No.3 and 4) by backprobing.

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

diagnostic trouble code.

Q: Is DTC 22 set?

YES : Go to Step 3.
NO : Replace the clock spring (Refer to

P.52B-217

). Then

go to Step 4.

AC100441AE

D-229 AIR BAG MODULE
CONNECTOR

STEERING WHEEL

A

AC303006AD

D-229 AIR BAG
MODULE
CONNECTOR

MB991865
(DUMMY RESISTOR : 3

Ω)

MB991866 (RESISTOR
HARNESS)

AC303587

D-206 CLOCK SPRING
CONNECTOR

AD

MB991865
(DUMMY RESISTOR : 3

Ω)

MB991866 (RESISTOR
HARNESS)

1 2

4

3

(REAR VIEW)

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-50

STEP 3. Check the harness between the SRS-ECU
connector E-08 (terminal No.11 and 12) and the clock
spring connector (terminal No.3 and 4) for open circuit.
(1) Disconnect SRS-ECU connector E-08 and clock spring

connector D-206, and measure at the wiring harness side.

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-08 terminal 11 and connector

D-206 terminal 3

• Between connector E-08 terminal 12 and connector

D-206 terminal 4

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

YES : Eras the diagnostic trouble code memory, and check

the diagnostic trouble code. If DTC 22 sets, replace
the SRS-ECU (Refer to

P.52B-215

). Then go to Step

4.

NO : Repair the harness wires between SRS-ECU

connector E-08 and clock spring connector D-206.
Then go to Step 4.

STEP 4. Recheck for diagnostic trouble code.
Q: Is DTC 22 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

).

ACX01478AM

CONNECTOR: E-08

E-08 (Y)

HARNESS SIDE
CONNECTOR
(REAR VIEW)

AC204226 AF

CONNECTOR: D-206

CLOCK SPRING

D-206 (Y)

HARNESS SIDE
CONNECTOR
(REAR VIEW)

1 2

4

3

1 2

4

3

AC200924

13 14 15 16 17 18 19 20

5 6 7 8 9 10 11 12

1 2

3 4

D-206
HARNESS SIDE
CONNECTOR
(REAR VIEW)

E-08
HARNESS SIDE
CONNECTOR
(REAR VIEW)

AI