Mitsubishi Evolution X. Manual — part 648

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-39

CAUTION

If DTC B1207 is set in the SRS-ECU, always diag-
nose the CAN main bus line.

.

CIRCUIT OPERATION

• Power for the passenger’s air bag OFF indicator

light is supplied from the ignition switch (IG1).

• The passenger’s air bag OFF indicator light illu-

minates when the ignition switch is turned to the
"ON" position and goes out after approximately
seven seconds if there is not a malfunction in the
SRS system.

.

DTC SET CONDITIONS

This DTC will be set if the passenger’s air bag OFF
indicator light driving circuit is short to ground.

.

TROUBLESHOOTING HINTS

• Damaged wiring harnesses or connectors

• Malfunction of the SRS-ECU

• Malfunction of the passenger’s air bag OFF indi-

cator light

DIAGNOSIS

Required Special Tools:

• MB991958: Scan Tool (M.U.T.-III Sub Assembly)

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

• MB991827: M.U.T.-III USB Cable

• MB991910: M.U.T.-III Main Harness A (Vehicles with

CAN Communication System)

AC708951AB

C-37 (Y)

C-124

Connectors: C-37, C-124

AC608152 AE

Connector: C-317

Junction block

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-40

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

CAUTION

To prevent damage to scan tool MB991958, always turn the
ignition switch to the "LOCK" (OFF) position before con-
necting or disconnecting scan tool MB991958.
(1) Connect scan tool MB991958. Refer to "How to connect the

scan tool

P.52B-28

."

(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

P.54C-14

).

STEP 2. 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 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 Cope with Intermittent
Malfunction

P.00-15

).

STEP 3. Check the passenger’s air bag OFF indicator light.
(1) It is checked whether the passenger’s air bag OFF indicator

light is normal (Refer to

P.52B-30

).

Q: Is the check result normal?

YES : Go to Step 4.
NO : Replace instrument center panel (Refer to GROUP

52A

− Instrument Panel Assembly

P.52A-2

).

AC608435

Data link connector

MB991827

MB991824

MB991910

AB

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-41

STEP 4. Resistance measurement at the C-124 instrument
center panel connector.
(1) Disconnect the negative battery terminal.
(2) Disconnect the C-124 instrument center panel connector.
(3) Take the measurements below at the instrument center

panel side connector. It should be open circuit.

• Continuity between terminal No.11 and ground

Q: Is the check result normal?

YES : Go to Step 5.
NO : Replace instrument center panel (Refer to GROUP

52A

− Instrument Panel Assembly

P.52A-2

).

STEP 5. Resistance measurement at the C-37 SRS-ECU
connector.
(1) Disconnect the negative battery terminal.
(2) While pushing the part "A" indicated in the figure of the

harness side connector, turn the lock lever to the direction
of the arrow to release the lock lever, and disconnect the
C-37 SRS-ECU connector.

(3) Take the measurements below at the SRS-ECU connector.

It should be open circuit.

• Continuity between terminal No.18 and body ground

Q: Is it open circuit?

YES : Go to Step 6.
NO : Repair the wiring harnesses between the C-37

SRS-ECU connector terminal No. 18 and the C-124
instrument center panel connector terminal No.11.

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 B1207 set?

YES : Replace SRS-ECU (Refer to

P.52B-383

).

NO : There is an intermittent malfunction such as poor

engaged connector(s) or open circuit (Refer to
GROUP 00, How to Cope with Intermittent
Malfunction

P.00-15

).

AC506734

A

AD

Lock lever

AC608812

C-37 Harness side
connector (front view)

HL

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-42

DTC B1B00: Driver's Air Bag Module (1st Squib) System (Shorted to Squib Circuit Ground)

DTC B1B04: Driver's Air Bag Module (2nd Squib) System (Shorted to Squib Circuit Ground)

CAUTION

If DTC B1B00 <1st squib> or B1B04 <2nd squib>
is set in the SRS-ECU, always diagnose the CAN
main bus line.

.

SRS-ECU

CLOCK
SPRING

DRIVER'S AIR BAG
MODULE (SQUIB)

CONNECTOR LOCK SWITCH

CONNECTOR COUPLED: ON

CONNECTOR UNCOUPLED: OFF

NOTE

:

Driver's Air Bag Module (Squib) Circuit

AC708951AC

C-37 (Y)

Connector: C-37

AC708953AB

Connectors: C-204, C-208

C-208 (Y)

C-204 (Y)