Mitsubishi Evolution X. Manual - part 666

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-111

NOTE: *: The squib circuit connectors integrate a 
"short" spring (which prevents the knee air bag mod-
ule from deploying unintentionally due to static elec-
tricity by shorting the positive wire to the ground wire 
in the squib circuit when the connectors are discon-
nected) (Refer to 

P.52B-3

). Therefore, if connector 

C-37 or C-39 is damaged or improperly engaged, the 
short spring may not be released when the connector 
is connected.

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)

• MB991865: Dummy resistor

• MB991884: 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-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

).

AC608435

Data link connector

MB991827

MB991824

MB991910

AB

SRS AIR BAG DIAGNOSIS

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SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-112

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-37 and Knee air bag 
module connector C-39.
(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. Then connect the connector.

(3) After disconnecting the C-39 harness side connectors, 

connect the connectors again. For the C-39 connector 
disconnection, use a flat-tipped screwdriver to unlock the 
locking button at the harness side connector by withdrawing 
it to ward 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 B1B13 set?

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

B1B13 set because connector C-37 or C-39 was 
engaged improperly.

AC506734

A

AD

Lock lever

AC609126AC

Locking button

Flat-tipped
screwdriver

Pre-tensioner

Harness side
connector

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-113

STEP 4. Check the knee air bag module. 
(1) Disconnect the negative battery terminal.
(2) Disconnect knee air bag module connector C-39. 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) Connect special tool MB991865 to special tool MB991884.
(4) Connect special tool MB991884 to the C-39 harness side 

connector.

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

diagnostic trouble code.

Q: Is DTC B1C36 set?

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

P.52B-398

. Then go to Step 7.

AC609126AC

Locking button

Flat-tipped
screwdriver

Pre-tensioner

Harness side
connector

AC301553CA

C-39 Harness side 
connector

MB991884 

(Resistor harness)

MB991865

(Dummy resistor: 3    )

SRS AIR BAG DIAGNOSIS

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SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-114

STEP 5. Check the knee air bag module circuit. Measure 
the resistance at the 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 knee air bag module from deploying 
unintentionally, disconnect the knee air bag module 
connector C-39 to short the squib circuit.

(3) Disconnect knee air bag module connector C-39. 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 1, 2 and the short spring to release 
the short spring.

AC506734

A

AD

Lock lever

AC609126AC

Locking button

Flat-tipped
screwdriver

Pre-tensioner

Harness side
connector

AC507302BJ

A

A

C-37 Harness side
connector (front view)

Section
A - A

Cable tie

Short spring

4 mm (0.16 inch) or more

Terminal