Mitsubishi Evolution X. Manual - part 674

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-143

STEP 3. Check by dummy resistor connection.
(1) Disconnect the negative battery terminal.
(2) Disconnect the D-10 intermediate connector (connection 

between curtain air bag harness and floor harness).

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

CAUTION

Do not insert a probe into the terminal from its front side 
directly, as the connector contact pressure may be weak-
ened.
(4) Insert the probe of resistor harness, to which the dummy 

resistor is installed, from the back of D-10 intermediate 
connector (floor harness side).

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

diagnostic trouble code again.

(7) Disconnect the negative battery terminal.
Q: Is DTC B1B20 set?

YES : Go to Step 4.
NO :  Go to Step 5.

AC507310

D-10 Intermediate connector
(Curtain air bag harness side)

D-10 
Intermediate 
connector 
(Floor harness side)

AI

MB991865
(Dummy resistor: 3    )

MB991866 

(Resistor harness)

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-144

STEP 4. Resistance measurement at the C-36 SRS-ECU 
connector 
(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 air bag from deploying unintentionally, 
disconnect the intermediate connector D-10 to short 
the squib circuit.

(3) Disconnect the D-10 intermediate connector (connection 

between curtain air bag harness and floor harness).

CAUTION

The short spring may not be released due to the insuffi-
cient insertion. Therefore, insert the insulator for 4 mm (0.6 
inch) or more.
(4) Insert a cable tie [3 mm (0.12 inch) wide, 0.5 mm (0.02 inch) 

thick] between terminal 39, 40 and the short spring to 
release the short spring.

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

connector terminal No. 39, 40 and body ground.
It should be open circuit.

Q: Is it open circuit?

YES : Go to Step 6.
NO :  Repair the wiring harness.

AC609027

A

AB

Lock lever

AC507303 BZ

A

A

C-36 Harness side
connector (front view)

Section
A - A

Cable tie

Short spring

4 mm (0.16 inch) or more

Terminal

AC608812

C-36 Harness side 
connector (front view)

FS

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-145

STEP 5. Resistance measurement at the D-10 intermediate 
connector.
(1) Disconnect the negative battery terminal.

DANGER

To prevent the air bag from deploying unintentionally, 
disconnect the curtain air bag module connector F-04 
to short the squib circuit.

(2) Disconnect curtain air bag module (RH) F-04. 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.

(3) Disconnect the D-10 intermediate connector (connection 

between curtain air bag harness and floor harness).

(4) Because the short spring is installed to the D-10 

intermediate connector (curtain air bag harness side), insert 
a cable tie [3 mm (0.12 inch) wide, 0.5 mm (0.02 inch) thick] 
between terminals 1, 2 and the short spring to release the 
short spring.

CAUTION

Do not insert a probe into the terminal from its front side 
directly as the connector contact pressure may be weak-
ened.
(5) Check for continuity between the D-10 intermediate 

connector (module side) terminal No. 1, 2 and body ground.
It should be open circuit.

Q: Is it open circuit?

YES : Replace the curtain air bag module (squib) (Refer to 

P.52B-409

).

NO :  Repair the wiring harness.

STEP 6. 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 B1B20 set?

YES : Replace SRS-ECU (Refer to 

P.52B-383

).

NO :  Intermittent Malfunction (Refer to GROUP 00, How to 

Use Troubleshooting/Inspection Service Points 

− How 

to Cope with Intermittent Malfunction 

P.00-15

).

AC609834AB

Locking 
button

Flat-tipped 
screwdriver

Inflator

Curtain air bag wiring 
harness connector

AC700119

D-10 Intermediate 
connector (module side ) 

22 mm or more

Cable tie

Short spring

AJ

AC608812GW

D-10 Intermediate connector 
(Curtain air bag harness side)
(rear view)

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-146

DTC B1B21: Curtain Air Bag Module (RH) (Squib) System (Shorted to Squib Circuit Power Supply)

SRS-ECU

NOTE

: CONNECTOR COUPLED : ON

CONNECTOR UNCOUPLED : OFF

Curtain Air Bag Module (Squib) (RH) Circuit

CURTAIN AIR BAG MODULE
(SQUIB) (RH)

CONNECTOR
LOCK SWITCH

CONNECTOR
LOCK 
SWITCH

CONNECTOR
LOCK SWITCH

AC708951AD

Connector: C-36

C-36 (Y)

AC708955AC

Connector: D-10

D-10 (Y)