Mitsubishi Evolution X. Manual - part 713

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-299

U0151

SRS-ECU CAN timeout

P.52B-344

U0155

Combination meter CAN timeout

P.52B-346

U0164

A/C-ECU CAN timeout

P.52B-347

U0168

KOS-ECU or WCM CAN timeout

P.52B-349

U0184

Audio CAN timeout

P.52B-350

U0195

Satellite radio tuner CAN timeout

P.52B-352

U0197

Hands free module CAN timeout

P.52B-353

U0245

Audio visual navigation unit CAN timeout

P.52B-355

U1419

The signal from a weight sensor (front: LH) is unusual

P.52B-356

U141A

The signal from a weight sensor (front: RH) is unusual

P.52B-356

U141B

The signal from a weight sensor (rear: LH) is unusual

P.52B-356

U141C

The signal from a weight sensor (rear: RH) is unusual

P.52B-356

U1423

The signal from a weight sensor is unusual

P.52B-356

Diagnostic trouble 
Code No.

Inspection item

Reference page

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-300

DIAGNOSTIC TROUBLE CODE PROCEDURES <OCCUPANT 
CLASSIFICATION-ECU>

DTC B1B78: Passenger Seat Weight Sensor (front: LH) Performance

 

DTC B1B7D: Passenger Seat Weight Sensor (front: RH) Performance

 

DTC B1B82: Passenger Seat Weight Sensor (rear: LH) Performance

 

DTC B1B87: Passenger Seat Weight Sensor (rear: RH) Performance

 

WEIGHT SENSOR 
(FRONT: LH)

WEIGHT SENSOR 
(REAR: LH)

WEIGHT SENSOR 
(REAR: RH)

WEIGHT SENSOR 
(FRONT: RH)

FRONT SEAT 
ASSEMBLY (RH)

OCCUPANT 
CLASSIFICATION-
ECU

Weight Sensor

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-301

CAUTION

If DTC B1B78, B1B7D, B1B82 or B1B87 is set in 
the occupant classification-ECU, always diag-
nose the CAN main bus lines.

.

CIRCUIT OPERATION

The load data from the weight sensor is classified 
with the occupant classification-ECU, and its classi-
fied information is send to SRS-ECU by CAN bus 
line. The SRS-ECU determines the air bag deploy-
ment based on this classified information, and con-
trols the power supply circuit to the inflator. 

.

DTC SET CONDITIONS

This DTC is set if the weight sensor output voltage is 
out of the range (guideline: 1 to 3.5 V).

.

TROUBLESHOOTING HINTS

• The weight sensor may be defective.

• Occupant classification-ECU may be defective.

• The wiring harness or connectors may have 

loose, corroded, or damaged terminals, or termi-
nals pushed back in the connector

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)

AC708954 AK

Connectors: D-39-1, D-39-3, D-39-4, 
D-39-5, D-39-6

D-39-1, D-39-3, 
D-39-4, D-39-5, 
D-39-6

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-302

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. 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 : Go to Step 3.
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

).

STEP 3. Check occupant classification-ECU connector 
D-39-1 and weight sensor connector D-39-3, D-39-4, D-39-5 
or D-39-6 for loose, corroded or damaged terminals, or 
terminals pushed back in the connector.
Q: Is occupant classification-ECU connector D-39-1, 

weight sensor connector D-39-3, D-39-4, D-39-5 or 
D-39-6 in good condition?
YES : Go to Step 4.
NO :  Repair or replace the component(s) (Refer to GROUP 

00E, Harness Connector Inspection 

P.00E-2

).

AC608435

Data link connector

MB991827

MB991824

MB991910

AB