Mitsubishi Evolution X. Manual - part 681

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-171

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. Check the side impact sensor.
(1) Disconnect the negative battery terminal.
(2) A side impact sensor is checked in the following way.

• Replace the left side impact sensor {In case of code 

B1B72 (Regardless of "Active" or "Stored" faults)} with 
the new parts.

• Replace the right side impact sensor {In case of code 

B1B75 (Regardless of "Active" or "Stored" faults)} with 
the new parts.

(3) Connect the negative battery terminal.
(4) After erasing the diagnostic trouble code memory, check the 

diagnostic trouble code again.

Q: Is either DTC No. B1B72 or B1B75 set?

YES : Go to Step 3.
NO :  The procedure is complete.

AC608435

Data link connector

MB991827

MB991824

MB991910

AB

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-172

STEP 3. Check the SRS-ECU.
(1) Disconnect the negative battery terminal.
(2) Replace the SRS-ECU with a new one (Refer to 

P.52B-383

). 

(3) Connect the negative battery terminal.
(4) Check the diagnostic trouble code again.
Q: Is either DTC No. B1B72 or B1B75 set?

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

DTC B1BA3: Driver’s Seat Slide Sensor Malfunction (Occupant Classification-ECU)

CAUTION

If DTC B1BA3 is set in the Occupant classifica-
tion-ECU, always diagnose the CAN main bus 
line.

.

DTC SET CONDITIONS

These DTCs are set if communication between the 
occupant classification-ECU and the seat slide sen-
sor is not possible or communication is faulty.

.

TROUBLESHOOTING HINTS

• Malfunction of the seat slide sensor

• Malfunction of occupant classification-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)

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-173

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. Using scan tool MB991958, read the occupant 
classification-ECU diagnostic trouble code.
Check if the DTC is set to the occupant classification-ECU.
Q: Is DTC set?

YES : Diagnose the occupant classification-ECU.
NO :  Go to Step 3.

STEP 3. 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 : Replace the 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

).

AC608435

Data link connector

MB991827

MB991824

MB991910

AB

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-174

DTC B1BA5: SRS-ECU squib count mismatch

CAUTION

If DTC B1BA5 is set in the SRS-ECU, always diag-
nose the CAN main bus line.

.

CIRCUIT OPERATION

SRS-ECU monitors the resistance value of each 
squib circuit on the vehicle. If any of the resistance 
values is outside the normal range, SRS-ECU sets 
the DTC.

.

DTC SET CONDITIONS

• If an SRS-ECU different from the unit compatible 

to vehicle is accidentally installed, this DTC will 
be set (If SRS-ECU for the vehicles with side-air 
bag is installed to the vehicles without side-air 
bag. However, the DTC is not set in the reverse 
case).

• If an open circuit occurs to the squib circuit, this 

DTC will be set.

.

TROUBLESHOOTING HINTS

• SRS-ECU incorrect installation

• Squib specification mismatch

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.
(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

).

AC608435

Data link connector

MB991827

MB991824

MB991910

AB