Mitsubishi Evolution X. Manual - part 655

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-67

STEP 4. Check the driver's air bag module.
(1) Disconnect the negative battery terminal.
(2) Slide the outer housing of the clock spring side of driver’s 

air bag module connector C-204 in the arrow direction 
shown, and disconnect the connector.

(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 special tool MB991866 into clock spring side of 

driver’s air bag module connector C-204 (terminal No.1 and 
2 <1st squib> or No.3 and 4 <2nd squib>) by backprobing.

(5) Connect the negative battery terminal.

CAUTION

Always DTC B1B06 is set when checking DTC B1B03. This 
is because the second side terminal is isolated when 
checking it. DTC B1B06 is set but this is not a fault. In 
addition, always DTC B1B02 is set when checking DTC 
B1B07 because the first side terminal is isolated. 
(6) Erase the diagnostic trouble code memory, and check the 

diagnostic trouble code.

Q: Is the checked DTC set?

YES : Go to Step 5.
NO :  Replace the driver's air bag module (Refer to 

P.52B-386

). Then go to Step 8. 

AC605948

AC600868

AF

Outer housing of the driver's air bag 
module connector

Driver's air bag module 
Connector (4 pin yellow)

Horn connector

Lower column 
cover

AC306758AY

MB991865 
(Dummy resistor: 3   )

MB991866 
(Resistor harness)

C-204 Air bag 
module connector

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-68

STEP 5. Check the clock spring.
(1) Disconnect the negative battery terminal.
(2) Disconnect the clock spring connector C-208.
(3) Connect special tool MB991865 to special tool MB991866.

CAUTION

Do not insert a probe into the terminal from C-208 harness 
side connector front side directly, as the connector contact 
pressure may be weakened.
(4) Insert special tool MB991866 into clock spring harness side 

connector C-208 (terminal No.3 and 4 <1st squib> or No.1 
and 2 <2nd squib>) by backprobing.

(5) Connect the negative battery terminal.

CAUTION

Always DTC B1B06 is set when checking DTC B1B03. This 
is because the second side terminal is isolated when 
checking it. DTC B1B06 is set but this is not a fault. In 
addition, always DTC B1B02 is set when checking DTC 
B1B07 because the first side terminal is isolated. 
(6) Erase the diagnostic trouble code memory, and check the 

diagnostic trouble code.

Q: Is the checked DTC set?

YES : Go to Step 6.
NO :  Replace the clock spring (Refer to 

P.52B-386

). Then 

go to Step 8. 

AC306767

C-208 Clock spring
connector

AR

MB991865 
(Dummy resistor: 3   )

MB991866 
(Resistor harness)

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-69

STEP 6. Check the driver’s air bag module circuit. Measure 
the resistance at SRS-ECU connector C-37.
(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-37 SRS-ECU connector.

DANGER

To prevent the air bag from deploying unintentionally, 
disconnect clock spring connector C-208 to short the 
squib circuit.

(3) Disconnect clock spring connector C-208.

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 5, 6 <1st squib> or 9, 10 <2nd 
squib> and the short spring to release the short spring.

AC506734

A

AD

Lock lever

AC507302 BF

A

A

C-37 Harness side
connector (front view)

Section
A - A

Cable tie

Short spring

Terminal

<1st Squib>

4 mm (0.16 inch) or more

AC507302BG

A

A

<2nd Squib>

C-37 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-70

(5) Check for continuity between C-37 harness side connector 

terminals 5 and 6 <1st squib> or 9 and 10 <2nd squib>.
It should be open circuit.

Q: Is it open circuit? 

YES : Erase the diagnostic trouble code memory, and check 

the diagnostic trouble code. If DTC B1B03 <1st 
squib> or B1B07 <2nd squib> set, replace the 
SRS-ECU (Refer to 

P.52B-383

). Then go to Step 8.

NO :  Go to Step 7. 

STEP 7. Check the harness for short circuit between 
SRS-ECU connector C-37 (terminal No.5 and 6 <1st squib> 
or No.9 and 10 <2nd squib>) and clock spring connector 
C-208 (terminal No.4 and 3 <1st squib> or No.1 and 2 <2nd 
squib>).
Q: Are harness wires between SRS-ECU connector C-37 

(terminal No.5 and 6 <1st squib> or No.9 and 10 <2nd 
squib>) and clock spring connector C-208 (terminal 
No.4 and 3 <1st squib> or No.1 and 2 <2nd squib>) in 
good condition?
YES : Go to Step 8.
NO :  Replace the harness wires between SRS-ECU 

connector C-37 and clock spring connector C-208. 
Then go to Step 8.

STEP 8. 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 B1B03 <1st squib> or B1B07 <2nd squib> set?

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

AC608812

C-37 Harness side 
connector (front view)

EY

<1st squib>

AC608812

C-37 Harness side 
connector (front view)

EZ

<2nd squib>