Mitsubishi Evolution X. Manual - part 660

SRS AIR BAG DIAGNOSIS

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SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-87

CAUTION

Insert an insulator such as a cable tie to a depth of 4 mm
(0.16 inch) or more, otherwise the short spring will not be
released.
(5) Insert a cable tie [3 mm (0.12 inch) wide, 0.5 mm (0.02 inch)

thick] between terminals 7 and 8 <1st squib> or 11 and 12
<2nd squib>, and the short spring to release the short
spring.

CAUTION

Do not insert a probe into the terminal from C-14 harness
side connector front side directly as the connector contact
pressure may be weakened.
(6) Check for continuity between the following terminals. It

should be less than 2 ohms.

• SRS-ECU connector C-37 (terminal No.7) and the pas-

senger’s (front) air bag module connector C-14 (terminal
No.2) <1st squib>

• SRS-ECU connector C-37 (terminal No.8) and the pas-

senger’s (front) air bag module connector C-14 (terminal
No.1) <1st squib>

• SRS-ECU connector C-37 (terminal No.11) and the pas-

senger’s (front) air bag module connector C-14 (terminal
No.4) <2nd squib>

• SRS-ECU connector C-37 (terminal No.12) and the pas-

senger’s (front) air bag module connector C-14 (terminal
No.3) <2nd squib>

Q: Does continuity exist?

YES : Erase the diagnostic trouble code memory, and check

the diagnostic trouble code. If DTC B1B0A <1st
squib> or B1B0E <2nd squib> set, replace the
SRS-ECU (Refer to

P.52B-383

). Then go to Step 5.

NO : Replace the harness wires between SRS-ECU

connector C-37 and passenger’s (front) air bag

AC507302 BH

<1st Squib>

C-37 Harness side
connector (front view)

Section
A - A

Cable tie

Short spring

4 mm (0.16 inch) or more

Terminal

AC507302 BI

<2nd Squib>

C-37 Harness side
connector (front view)

Section
A - A

Cable tie

Short spring

4 mm (0.16 inch) or more

Terminal

AC608812

C-37 Harness side
connector (front view)

C-14 Harness side
connector (rear view)

<1st squib>

AC608812

<2nd squib>

C-37 Harness side
connector (front view)

C-14 Harness side
connector (rear view)

SRS AIR BAG DIAGNOSIS

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SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-88

module connector C-14. 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 B1B0A <1st squib> or B1B0E <2nd squib> set?

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

DTC B1B0B: Passenger's (Front) Air Bag Module (1st squib) System (Short Circuit Between Squib
Circuit Terminals)

DTC B1B0F: Passenger's (Front) Air Bag Module (2nd squib) System (Short Circuit Between Squib
Circuit Terminals)

PASSENGER'S (FRONT)
AIR BAG MODULE
(SQUIB)

SRS-ECU

CONNECTOR LOCK SWITCH

CONNECTOR COUPLED: ON

CONNECTOR UNCOUPLED: OFF

NOTE

Passenger's (Front) Air Bag Module (Squib) Circuit

SRS AIR BAG DIAGNOSIS

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SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-89

CAUTION

If DTC B1B0B <1st squib> or B1B0F <2nd squib>
is set in the SRS-ECU, always diagnose 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 SRS
air bag will inflate.

• The ignition signal is input to the air bag module

to inflate the air bag.

DTC SET CONDITIONS

This DTC is set if there is abnormal resistance
between the input terminals of the passenger's
(front) air bag module (squib).

TROUBLESHOOTING HINTS

• Improper engaged connector or defective short

spring*

• Short circuit between the passenger's (front) air

bag module (squib) circuit terminals

• Damaged connector(s)

• Malfunction of the SRS-ECU

NOTE: *: The squib circuit connectors integrate a
"short" spring (which prevents the air bag from
deploying unintentionally due to static electricity by
shorting the positive wire to the ground wire in the
squib circuit when the connectors are disconnected)
(Refer to

P.52B-3

). Therefore, if connector C-14 or

C-37 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 resister

• MB991866: Resister harness

AC708951AE

C-37 (Y)

C-14 (Y)

Connectors: C-14, C-37

SRS AIR BAG DIAGNOSIS

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SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-90

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 the "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

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