Mitsubishi Evolution X. Manual - part 700

 

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Mitsubishi Evolution X. Manual - part 700

 

 

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-247

STEP 4. Check the harness for open circuit between 
SRS-ECU connector C-36 (terminal No.43 and 44) and the 
passenger's seat belt pre-tensioner connector D-40 
(terminal No.2 and 1).
(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 SRS-ECU connector C-36 and passenger's 

seat belt pre-tensioner connector D-40. For 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-248

(5) Connect D-40 harness side connector to special tool 

MB991884.

(6) Check for continuity between the following terminals. It 

should be less than 2 ohms. 

• SRS-ECU connector C-36 (terminal No.43) and the spe-

cial tool (terminal No.1)

• SRS-ECU connector C-36 (terminal No.44) and the spe-

cial tool (terminal No.2)

Q: Does continuity exist?

YES : Erase the diagnostic trouble code memory, and check 

the diagnostic trouble code. If DTC B1C49 sets, 
replace the SRS-ECU (Refer to 

P.52B-383

). Then go 

to Step 5.

NO :  Replace the harness wires between SRS-ECU 

connector C-36 passenger’s seat belt pre-tensioner 
connector D-40. Then go to Step 5.

STEP 5. 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 B1C49 set?

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

AC201287EM

D-40 Harness side 
connector

MB991884 
(Resistor harness)

AC608812GO

C-36 Harness side 
connector (front view)

Resistor harness 
side connector

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-249

DTC B1C4A: Front Passenger's Pre-tensioner (Squib) System (Short Circuit between Squib Circuit 
Terminals)

CAUTION

If DTC B1C4A is set in the SRS-ECU, always diag-
nose the CAN main bus line.

.

CIRCUIT OPERATION

The SRS-ECU judges how severe a collision is by 
detecting signals from the front impact sensors and 
the front air bag analog G-sensor. If the impact is 
over a predetermined level, the SRS-ECU sends an 
ignition signal. At this time, if the front air bag safing 
G-sensor is on, the pre-tensioner will deploy. 

.

DTC SET CONDITIONS

This DTC is set if there is abnormal resistance 
between the input terminals of the passenger’s seat 
belt pre-tensioner (squib).

.

TROUBLESHOOTING HITS

• Improper engaged connector or defective short 

spring*

• Short circuit between the passenger's seat belt 

pre-tensioner (squib) circuit terminals

• Damaged connector(s)

• Malfunction of the SRS-ECU

SEAT BELT
PRE-TENSIONER (RH)

CONNECTOR
LOCK 
SWITCH

CONNECTOR
LOCK SWITCH

SRS-ECU

Seat Belt Pre-Tensioner (RH) (Squib) Circuit

AC708951AD

Connector: C-36

C-36 (Y)

AC708954 AH

Connector: D-40

D-40 (B)

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-250

NOTE: *: The squib circuit connectors integrate a 
"short" spring (which prevents the seat belt pre-ten-
sioner from deploying unintentionally due to static 
electricity by shorting the positive wire to the ground 
wire in the squib circuit when the connectors are dis-
connected) (Refer to 

P.52B-3

). Therefore, if connec-

tor C-36 or D-40 is damaged or improperly engaged, 
the short spring may not be released when the con-
nector 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

 

 

 

 

 

 

 

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