Mitsubishi Evolution X. Manual — part 657

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-75

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.

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

terminals 7 and 8 <1st squib> or 11 and 12 <2nd squib>,
and body ground.
It should be an open circuit.

Q: Is it open circuit?

YES : Erase the diagnostic trouble code memory, and check

the diagnostic trouble code. If DTC B1B08 <1st
squib> B1B0C <2nd squib> sets, replace the
SRS-ECU (Refer to

P.52B-383

). Then go to Step 6.

NO : Go to Step 5.

AC507302 BH

A

A

<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

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

AC608812

C-37 Harness side
connector (front view)

FE

<1st squib>

AC608812

C-37 Harness side
connector (front view)

FF

<2nd squib>

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-76

STEP 5. Check the harness wires for short circuit to
ground between SRS-ECU connector C-37 (terminal No.7
and 8 <1st squib> or terminal No.11 and 12 <2nd squib>)
and passenger's (front) air bag module connector C-14
(terminal No.2 and 1 <1st squib> or terminal No.4 and 3
<2nd squib>).
Q: Are the harness wires between SRS-ECU connector

C-37 (terminal No.7 and 8 <1st squib> or terminal No.11
and 12 <2nd squib>) and passenger's (front) air bag
module connector C-14 (terminal No.2 and 1 <1st squib>
or terminal No.4 and 3 <2nd squib>) in good condition?
YES : Go to Step 6.
NO : Replace the harness wires between SRS-ECU

connector C-37 and passenger's (front) air bag
module connector C-14. 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 B1B08 <1st squib> B1B0C <2nd squib> set?

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

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-77

DTC B1B09: Passenger's (Front) Air Bag Module (1st squib) System (Shorted to Squib Circuit Power
Supply)

DTC B1B0D: Passenger's (Front) Air Bag Module (2nd squib) System (Shorted to Squib Circuit Power
Supply

CAUTION

If DTC B1B09 <1st squib> or B1B0D <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.

.

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

AC708951AE

C-37 (Y)

C-14 (Y)

Connectors: C-14, C-37

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-78

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

• Damaged harness wires and connectors

• Short to the power supply in the passenger's

(front) air bag module (squib) harness

• 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

• MB991866: 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