Mitsubishi Evolution X. Manual - part 699

SRS AIR BAG DIAGNOSIS

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SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-243

STEP 5. Check the harness wires for short circuit to power 
supply 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 the harness wires 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) in 
good condition?
YES : Go to Step 6.
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 6.

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 B1C48 set?

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

DTC B1C49: Front Passenger's Pre-tensioner (Squib) System (Squib Circuit Open)

SEAT BELT
PRE-TENSIONER (RH)

CONNECTOR
LOCK 
SWITCH

CONNECTOR
LOCK SWITCH

SRS-ECU

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

SRS AIR BAG DIAGNOSIS

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SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

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CAUTION

If DTC B1C49 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

• Open circuit in the passenger's seat belt pre-ten-

sioner (squib) circuit

• Improper connector contact

• Malfunction of the SRS-ECU

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

AC708951AD

Connector: C-36

C-36 (Y)

AC708954 AH

Connector: D-40

D-40 (B)

SRS AIR BAG DIAGNOSIS

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SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

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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

).

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

).

AC608435

Data link connector

MB991827

MB991824

MB991910

AB

SRS AIR BAG DIAGNOSIS

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SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-246

STEP 3. Check the passenger's seat belt pre-tensioner.
(1) Disconnect the negative battery terminal.
(2) 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.

(3) Connect special tool MB991865 to special tool MB991884.
(4) Connect special tool MB991884 to the D-40 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 B1C49 set?

YES : Go to Step 4.
NO :  Replace the passenger's seat belt with pre-tensioner 

(Refer to 

P.52B-413

). Then go to Step 5.

AC609576AB

Pre-tensioner

Harness side
connector

Locking 
button

Flat-tipped
screwdriver

AC301553CC

D-40 Harness side 
connector

MB991884 

(Resistor harness)

MB991865

(Dummy resistor: 3    )