Mitsubishi Evolution X. Manual - part 729

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-363

.

CIRCUIT OPERATION

• The SRS warning light illuminates when the igni-

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

• SRS-ECU sends the SRS warning light signal to 

the combination meter via the CAN communica-
tion.

• As a cause, the failure of CAN bus line, combina-

tion meter, or SRS-ECU is suspected.

.

TROUBLESHOOTING HINTS

• Damaged wiring harness and connectors

• Combination meter malfunction

• Malfunction of SRS-ECU

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)

AC708950

Connector: C-04

AR

AC708951AC

C-37 (Y)

Connector: C-37

AC708972BF

Connectors: C-309, C-317

Junction block

C-317

C-309 (B)

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-364

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.
Use scan tool MB991958 to diagnose the CAN bus lines.
(1) Connect scan tool MB991958 to the data link connector.
(2) Turn the ignition switch to the "ON" position.
(3) Diagnose the CAN bus line.
Q: Is the check result satisfactory?

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

Diagnosis 

P.54C-14

).

STEP 2. SRS warning light check
(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) Connect the negative battery terminal.
(4) Ignition switch: ON
Q: Does the lamp illuminate?

YES : Replace SRS-ECU (Refer to 

P.52B-383

).

NO :  Go to Step 3.

STEP 3. Wiring harness inspection between fusible link 
(34) and C-04 combination meter connector terminal No. 2 
NOTE: Prior to the wiring harness inspection, check the 
ETACS-ECU connectors C-309 and C-317, and repair if neces-
sary.

• The SRS warning light inspection for open and short circuit

Q: Is the check result normal?

YES : Replace the combination meter. (Refer to GROUP 

54A, Combination Meter 

P.54A-101

.)

NO :  Repair the wiring harness.

AC608435

Data link connector

MB991827

MB991824

MB991910

AB

AC506734

A

AD

Lock lever

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-365

Inspection Procedure 4: The SRS warning light does not go out.

.

CIRCUIT OPERATION

• The SRS warning light illuminates when the igni-

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

• SRS-ECU sends the SRS warning light signal to 

the combination meter via the CAN communica-
tion.

• As a cause, the failure of CAN bus line, combina-

tion meter, or SRS-ECU is suspected.

ETACS-ECU

COMBINATION METER

CPU

FUSIBLE
LINK

34

CAN DRIVE
CIRCUIT

IGNITION
SWITCH (IG1)

IG1
RELAY

INTERFACE
CIRCUIT

CAN TRANSCEIVER 
CIRCUIT

LED DRIVE 
CIRCUIT

JOINT CONNECTOR
(CAN1)

SRS-ECU

SRS Warning Light Circuit

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-366

.

TROUBLESHOOTING HINTS

• Damaged wiring harness and connectors

• Combination meter malfunction

• Malfunction of SRS-ECU

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)

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.
Use scan tool MB991958 to diagnose the CAN bus lines.
(1) Connect scan tool MB991958 to the data link connector.
(2) Turn the ignition switch to the "ON" position.
(3) Diagnose the CAN bus line.
Q: Is the check result satisfactory?

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

Diagnosis 

P.54C-14

).

STEP 2. Using scan tool MB991958, check actuator test
Check the combination meter actuator tests.
Item No. 07: Indicator 1
Q: Does the SRS warning light turn on and off normally?

YES : Go to Step 3.
NO :  Replace the combination meter. (Refer to GROUP 

54A, Combination Meter 

P.54A-101

.)

AC608435

Data link connector

MB991827

MB991824

MB991910

AB