Mitsubishi Evolution X. Manual - part 717

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-315

STEP 4. Check the wiring harness between the occupant 
classification-ECU connector D-39-2 (terminal 27 and 29) 
and the seat slide sensor D-32 (terminal 2 and 1).
Q: Check for continuity between occupant 

classification-ECU connector D-39-2 (terminal 27 and 
29) and the seat slide sensor D-32 (terminal 2 and 1)?
YES : Go to Step 5.
NO :  The wiring harness may be damaged or the 

connector(s) may have loose, corroded or damaged 
terminals, or terminals pushed back in the connector. 
Repair the wiring harness as necessary.

STEP 5. Recheck for diagnostic trouble code.
Check again if the DTC is set to the occupant classifica-
tion-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 slide adjuster (LH) (Refer to GROUP 

52A, Front Seat Assembly 

P.52A-24

).

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

).

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-316

DTC B1B8D: Seat Slide Sensor Open Circuit

CAUTION

If DTC B1B8D is set in the occupant classifica-
tion-ECU, always diagnose the CAN main bus 
lines.

.

CIRCUIT OPERATION

• The seat slide sensor sets the current value Hi or 

Low determined by the seat position.

• The occupant classification-ECU determines the 

seat position according to the current value from 
the seat slide sensor.

.

DTC SET CONDITIONS

• This DTC is set if there is abnormal resistance 

between the input terminals of the seat slide sen-
sor. The most likely causes for this code to be set 
are the followings: 

• Open circuit in the seat slide sensor or har-

ness

• Malfunction of connector contact

.

OCCUPANT 
CLASSIFICATION-
ECU

HALL IC

SEAT SLIDE 
SENSOR (LH)

FRONT SEAT 
ASSEMBLY (RH)

Seat Slide Sensor Circuit

AC708954 AM

D-32 (GR)

Connectors: D-32, D-39, D-39-2

D-39, D-39-2

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-317

TROUBLESHOOTING HINTS

• Open circuit in the seat slide sensor circuit

• Disengaged seat slide sensor connector

• Improper connector contact

• Malfunction of the seat slide sensor

• Malfunction of the 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)

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

).

AC608435

Data link connector

MB991827

MB991824

MB991910

AB

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-318

STEP 3. Check the harness for open circuit between 
occupant classification-ECU connector D-39-2 (terminal 
No.27 and 29) and the seat slide sensor connector D-32 
(terminal No.2 and 1).
(1) Disconnect occupant classification-ECU connector D-39-2 

and seat slide sensor connector D-32.

CAUTION

Do not insert a test probe into the terminal from its front 
side directly, as the connector contact pressure may be 
weakened.
(2) Check for continuity between the following terminals. It 

should be less than 2 ohms.

• Occupant classification-ECU connector D-39-2 (terminal 

No.27) and the seat slide sensor connector D-32 (termi-
nal No.2)

• Occupant classification-ECU connector D-39-2 (terminal 

No.29) and the seat slide sensor connector D-32 (termi-
nal No.1)

Q: Does continuity exist?

YES : Erase the diagnostic trouble code memory, and check 

the diagnostic trouble code. If DTC B1B8D sets, 
replace the slide adjuster (LH) (Refer to GROUP 52A, 
Front Seat Assembly 

P.52A-24

).

NO :  Repair the harness wires between occupant 

classification-ECU connector D-39-2 and seat slide 
sensor connector D-32. Then go to Step 4.

STEP 4. Recheck for diagnostic trouble code.
Check again if the DTC is set to the occupant classifica-
tion-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 B1B8Dset?

YES : Replace the slide adjuster (LH) (Refer to GROUP 

52A, Front seat assembly 

P.52A-24

).

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

).

AC608812

D-32 Harness side 
connector (rear view)

HM

D-39-2 Harness side 
connector (

rear

 view)