Mitsubishi Evolution X. Manual - part 707

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-275

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 (M.U.T.-III) 

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

YES : Diagnose the A/C.
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

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SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-276

DTC U0168: KOS-ECU or WCM CAN Timeout

CAUTION

• If DTC U0168 is set, be sure to diagnose the 

CAN bus line.

• When replacing the ECU, always check that 

the communication circuit is normal.

.

DIAGNOSTIC FUNCTION

If the signal from KOS-ECU or WCM cannot be 
received, the SRS-ECU sets the DTC U0168.

.

JUDGMENT CRITERIA

Because of the CAN-B bus circuit malfunction, if 
SRS-ECU becomes unable to perform the normal 
data transmission, SRS-ECU determines that an 
abnormality is present.

.

TROUBLESHOOTING HINTS

• Malfunction of CAN bus line may be defective.

• Malfunction of the KOS-ECU may be defective.

• Malfunction of the WCM may be defective.

• Malfunction of 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)

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 (M.U.T.-III) 

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-277

STEP 2. Using scan tool MB991958, read the KOS-ECU or 
WCM diagnostic trouble code
Check again if the DTC is set to the KOS-ECU or WCM.
Q: Is the DTC set?

YES : Diagnose the KOS or WCM.
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

).

DTC U0170: Front Impact Sensor (LH) Communication Error

FRONT IMPACT 
SENSOR (LH)

ACCELERO
METER

CPU

SRS-ECU

Front Impact Sensor (LH) Circuit

SRS AIR BAG DIAGNOSIS

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SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-278

CAUTION

If DTC U0170 is set in the SRS-ECU, always diag-
nose the CAN main bus line.

.

CIRCUIT OPERATION

If an impact of set value or more is detected, the front 
impact sensor sends the coded acceleration data to 
SRS-ECU. Based on the acceleration data, 
SRS-ECU determines the necessity of driver's and 
front passenger's air bag deployment, and then turns 
ON the power supply circuit to the inflator.

.

DTC SET CONDITIONS

These DTCs are set if communication between the 
front impact sensor (LH) and the SRS-ECU is not 
possible or faulty.

.

TROUBLESHOOTING HINTS

• Damaged wiring harnesses or connectors

• Malfunction of the front impact sensor (LH)

• Malfunction of the 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)

AC708949AC

Connectors: A-42, A-46

A-42 (B)

A-46 (Y)

AC708951AC

C-37 (Y)

Connector: C-37

AC708950AG

C-131

Connector: C-131