Mitsubishi Evolution X. Manual - part 706

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-271

STEP 2. Using scan tool MB991958, read the ETACS-ECU 
diagnostic trouble code
Check again if the 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

).

DTC U0154: Occupant Classification-ECU CAN Timeout

CAUTION

• If the DTC U0154 is set, be sure to diagnose 

the CAN main bus line.

• When replacing the ECU, always check that 

the communication circuit is normal.

.

DIAGNOSTIC FUNCTION

When the signals from occupant classification-ECU 
cannot be received, the SRS-ECU sets the DTC 
U0154.

.

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

• The CAN bus line may be defective

• The occupant classification-ECU may be defec-

tive

• 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-272

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 the 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 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-273

DTC U0155: Combination Meter CAN Timeout

CAUTION

• If the DTC U0155 is set, be sure to diagnose 

the CAN main bus line.

• When replacing the ECU, always check that 

the communication circuit is normal.

.

TROUBLE JUDGMENT

If the signal from combination meter cannot be 
received, the SRS-ECU sets the DTC U0155.

.

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

• The CAN bus line may be defective

• The combination meter 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)

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-274

STEP 2. Using scan tool MB991958, read the combination 
meter diagnostic trouble code
Check if DTC is set to the combination meter.
Q: Is the DTC set?

YES : Diagnose the combination meter.
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 U0164: A/C-ECU CAN Timeout

CAUTION

• If the DTC U0164 is set, be sure to diagnose 

the CAN main bus line.

• When replacing the ECU, always check that 

the communication circuit is normal.

.

DIAGNOSTIC FUNCTION

If the signal from A/C-ECU cannot be received, the 
SRS-ECU sets the DTC U0164.

.

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

• The CAN bus line may be defective

• The A/C-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)