Mitsubishi Evolution X. Manual - part 701

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-251

STEP 2. Recheck for diagnostic trouble code.
Check again if the DTC is set.
(1) Erase the DTC.
(2) Turn the ignition switch to "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 SRS-ECU connector C-36 and passenger’s 
seat belt pre-tensioner connector D-40.
(1) Disconnect the negative battery terminal.
(2) While pushing the part "A" indicated in the figure of the 

harness side connector, turn the lock lever to the direction 
of the arrow to release the lock lever, and disconnect the 
C-36 SRS-ECU connector. Then connect the connector.

(3) After disconnecting the D-40 harness side connectors, 

connect the connectors again. For the D-40 connector 
disconnection, use a flat-tipped screwdriver to unlock the 
locking button at the harness side connector by withdrawing 
it toward you in two stages, and then disconnect the 
connector.

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

diagnostic trouble code.

Q: Is DTC B1C4A set?

YES : Go to Step 4.
NO :  The procedure is complete. It is assumed that DTC 

B1C4A set because connector C-36 or D-40 was 
engaged improperly.

AC507645

A

AC

Lock lever

AC609576AB

Pre-tensioner

Harness side
connector

Locking 
button

Flat-tipped
screwdriver

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-252

STEP 4. Check the passenger's seat belt pre-tensioner.
(1) Disconnect the negative battery terminal.
(2) While pushing the part "A" indicated in the figure of the 

harness side connector, turn the lock lever to the direction 
of the arrow to release the lock lever, and disconnect the 
C-36 SRS-ECU connector.

(3) Disconnect passenger's seat belt pre-tensioner connector 

D-40. Use a flat-tipped screwdriver to unlock the locking 
button at the harness side connector by withdrawing it 
toward you in two stages, and then disconnect the 
connector.

(4) Connect special tool MB991865 to special tool MB991884.
(5) Connect special tool MB991884 to the D-40 harness side 

connector.

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

diagnostic trouble code.

Q: Is DTC B1C4A set?

YES : Go to Step 5.
NO :  Replace the passenger's seat belt with pre-tensioner 

(Refer to 

P.52B-413

). Then go to Step 7. 

AC507645

A

AC

Lock lever

AC609576AB

Pre-tensioner

Harness side
connector

Locking 
button

Flat-tipped
screwdriver

AC301553CC

D-40 Harness side 
connector

MB991884 

(Resistor harness)

MB991865

(Dummy resistor: 3    )

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-253

STEP 5. Check the passenger's seat belt pre-tensioner 
circuit. Measure the resistance at the SRS-ECU connector 
C-36.
(1) Disconnect the negative battery terminal.
(2) While pushing the part "A" indicated in the figure of the 

harness side connector, turn the lock lever to the direction 
of the arrow to release the lock lever, and disconnect the 
C-36 SRS-ECU connector.

DANGER

To prevent the seat belt pre-tensioner from deploying 
unintentionally, disconnect the passenger’s seat belt 
pre-tensioner connector D-40 to short the squib cir-
cuit.

(3) Disconnect passenger's seat belt pre-tensioner connector 

D-40. Use a flat-tipped screwdriver to unlock the locking 
button at the harness side connector by withdrawing it 
toward you in two stages, and then disconnect the 
connector.

CAUTION

Insert an insulator such as a cable tie to a depth of 4mm 
(0.16 inch) or more, otherwise the short spring will not be 
released.
(4) Insert a cable tie [3 mm (0.12 inch) wide, 0.5 mm (0.02 inch) 

thick] between terminals 43, 44 and the short spring to 
release the short spring.

AC507645

A

AC

Lock lever

AC609576AB

Pre-tensioner

Harness side
connector

Locking 
button

Flat-tipped
screwdriver

AC507303 CD

A

A

C-36 Harness side
connector (front view)

Section
A - A

Cable tie

Short spring

4 mm (0.16 inch) or more

Terminal

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-254

(5) Check for continuity between C-36 harness side connector 

terminals 43 and 44.
It should be an open circuit.

Q: Is it open circuit?

YES : Erase the diagnostic trouble code memory, and check 

diagnostic trouble code. If DTC B1C4A set, replace 
the SRS-ECU (Refer to 

P.52B-383

). Then go to Step 

7 .

NO :  Go to Step 6.

STEP 6. Check the harness for short circuit between 
SRS-ECU connector C-36 (terminal No.43 and 44) and 
passenger’s seat belt pre-tensioner connector D-40 
(terminal No.2 and 1).
Q: Are harness wires between SRS-ECU connector C-36 

(terminal No.43 and 44) connector and passenger’s seat 
belt pre-tensioner connector D-40 (terminal No.2 and 1) 
in good condition?
YES : Go to Step 7.
NO :  Replace the harness wires between SRS-ECU 

connector C-36 and passenger’s seat belt 
pre-tensioner connector D-40. Then go to Step 7.

STEP 7. 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 DTC B1C4A set?

YES : Return to Step 1.
NO :  The procedure is complete.

AC608812

C-36 Harness side 
connector (front view)

GM