Mitsubishi Evolution X. Manual - part 682

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-175

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 : If DTC B1BA5 is set, replace the SRS-ECU..
YES : If DTC code No.B1BA5 and other codes are set, 

perform the troubleshooting for the corresponding 
code.

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

).

DTC B1BAA: Occupant Classification-ECU Configuration Mismatch

CAUTION

• If the DTC B1BAA is set, diagnose the CAN 

main bus lines.

• When replacing the ECU, always check that 

the communication circuit is normal.

.

DIAGNOSTIC FUNCTION

If the information data and coding data on occupant 
classification-ECU do not suit. The SRS-ECU sets 
the DTC B1BAA

.

TROUBLESHOOTING HINTS

• The CAN bus line may be defective

• The ETACS-ECU may be defective

• The SRS-ECU may be defective

DIAGNOSIS

Required Special Tools:

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

• MB991824: Vehicles 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-176

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 ETACS-ECU 
diagnostic trouble code
Check if DTC is set to the ETACS-ECU.
Q: Is the DTC set?

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

STEP 3. Recheck for diagnostic trouble code.
Check again if the DTC is set to the SRS-ECU.
(1) Erase the DTC.
(2) Turn the ignition switch from "LOCK" (OFF) position to "ON" 

position.

(3) Check if 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 use Troubleshooting/inspection 
Service Points 

P.00-15

).

AC608435

Data link connector

MB991827

MB991824

MB991910

AB

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-177

DTC B1BC7: SRS-ECU (Record Data Full) System

CAUTION

If the diagnostic trouble code B1BC7 is set to 
SRS-ECU, always diagnose the CAN main bus 
line.

.

CIRCUIT OPERATION

If SRS-ECU determines that a collision has occurred, 
it sends the ignition current to deploy the air bag. It 
stores the deployment status. If this DTC is set, 
SRS-ECU determines that the air bag has been 
deployed.

.

DTC SET CONDITIONS

This DTC is set after the air bag deployment. If this 
DTC is set before the air bag is deployed, an internal 
failure may have occurred in SRS-ECU.

.

TROUBLESHOOTING HINTS

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.
(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

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-178

STEP 2. Recheck for diagnostic trouble code.
Check again if the DTC is set.
(1) Turn the ignition switch to the "ON" position.
(2) Check if the DTC is set.
(3) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Are any "Stored" or "Active" DTC B1BC7 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

).

DTC B1C27: Side-air bag Module (LH) (Squib) System (Shorted to Squib Circuit Ground)

SIDE-AIR BAG MODULE
(SQUIB) (LH)

CONNECTOR
LOCK 
SWITCH

CONNECTOR
LOCK 
SWITCH

SRS-ECU

Side-airbag Module (Squib) (LH) Circuit

NOTE

: CONNECTOR COUPLED : ON

CONNECTOR UNCOUPLED : OFF