Mitsubishi Galant 9G. Manual - part 1470

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-290

DTC B1508: Seat Slide Sensor System Fault Power Supply Circuit (Short-Circuited to Power Supply)

CAUTION

If DTC B1508 is set in the combination meter, 
always diagnose the CAN bus lines.

.

CIRCUIT OPERATION

• The seat slide sensor sets the current value Hi or 

Low determined by the seat position.

• The SRS-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 sensor.

.

TROUBLESHOOTING HINTS

• Damaged wiring harnesses or connectors

• Short to the power supply in the seat slide sensor 

harness

• Malfunction of the SRS-ECU

.

  Seat Slide Sensor Circuit

SEAT SLIDE
SENSOR

HALL IC

SEAT SLIDE SENSOR
DETECTION CIRCUIT

SRS-ECU

AC305362

CONNECTOR: C-122

C-122 (Y)

AE

SRS-ECU

AC308165

CONNECTOR : D-27

AB

D-27 (GR)

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-291

DIAGNOSIS

Required Special Tools:

•  MB991958: Scan Tool (MUT-III Sub Assembly)

• MB991824: Vehicle Communication Interface (V.C.I.)

• MB991827: MUT-III USB Cable

• MB991910: MUT-III Main Harness A (Vehicles with CAN 

Communication System)

• MB991865: Dummy resistor

• MB991866: Resister harness

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-30

."

(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 ).

AC305412

AB

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827

SRS AIR BAG DIAGNOSIS

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SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-292

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 Use Troubleshooting/Inspection 
Service Points 

− How to Cope with Intermittent 

Malfunctions ).

STEP 3. Check the seat slide sensor. (Using scan tool 
MB991958, read the diagnostic trouble code.)
(1) Disconnect the negative battery terminal.
(2) Disconnect the seat slide sensor connector D-27.

(3) Connect special tool MB991865 to special tool MB991866.

CAUTION

Do not insert a test probe into the terminal from its front 
side directly, as the connector contact pressure may be 
weakened.
(4) Insert special tool MB991866 into the D-27 harness side 

connector by backprobing.

(5) Connect the negative battery terminal.
(6) Erase the diagnostic trouble code memory, and check the 

diagnostic trouble code. 

Q: Is DTC B1508 set?

YES : Go to Step 4.
NO :  Replace the seat slide sensor (Refer to 

P.52B-384

). 

Then go to Step 5.

AC305412

AB

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827

AC308165

CONNECTOR : D-27

AC

D-27 (GR)

HARNESS SIDE

AC006042BQ

MB991866
(RESISTOR HARNESS)

D-27 HARNESS SIDE
CONNECTOR

D-27 SEAT SLIDE
SENSOR CONNECTOR

MB991865 (DUMMY 
RESISTOR: 3

 

Ω

)

(REAR VIEW)

SRS AIR BAG DIAGNOSIS

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SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-293

STEP 4. Check the seat slide sensor circuit. Measure the 
voltage at the SRS-ECU connector C-122.
(1) Disconnect SRS-ECU connector C-122.

(2) Disconnect seat slide sensor connector D-27.
(3) Turn the ignition switch to the "ON" position.

CAUTION

Do not insert a test probe into the terminal from its front 
side directly, as the connector contact pressure may be 
weakened.
(4) Measure the voltage between C-122 harness side 

connector terminals 1, 2 and body ground.
Voltage should measure 0 volt.

Q: Is the measured voltage within the specified range?

YES : Erase the diagnostic trouble code memory, and check 

the diagnostic trouble code. If DTC B1508 sets, 
replace the SRS-ECU (Refer to 

P.52B-365

). Then go 

to Step 6.

NO :  Go to Step 5.

AC305362

CONNECTOR: C-122

C-122 (Y)

AI

SRS-ECU

C-122 
Harness side
connector 
(rear view)

A

B

18

10

15

7

13

5

14

6

16

8

17

9

19

11

20

12

1 2

3 4

AC308165

CONNECTOR : D-27

AC

D-27 (GR)

HARNESS SIDE

AC308187

A

B

18

10

15

7

13

5

14

6

16

8

17

9

19

11

20

12

1 2

3 4

C-122 HARNESS SIDE
CONNECTOR
(REAR VIEW)

AB