Mitsubishi Evolution X. Manual — part 652

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-55

(7) Measure the voltage between C-37 harness side connector

terminals 5 and 6 <1st squib> or 9 and 10 <2nd squib> and
body ground.
Voltage should measure 0 volt.

Q: Is the measured voltage within the specified range?

YES : Erase the diagnostic trouble code memory, and check

the diagnostic trouble code. If DTC B1B01 <1st
squib> or B1B05 <2nd squib> sets, replace the
SRS-ECU (Refer to

P.52B-383

). Then go to Step 7.

NO : Go to Step 6.

STEP 6. Check the harness for short circuit to power
supply between SRS-ECU connector C-37 (terminal No.5
and 6 <1st squib> or terminal No.9 and 10 <2nd squib>)
and clock spring connector C-208 (terminal No.4 and 3
<1st squib> or terminal No. 1 and 2 <2nd squib>).
Q: Are harness wires between the SRS-ECU connector

C-37 (terminal No.5 and 6 <1st squib> or terminal No.9
and 10 <2nd squib>) and clock spring connector C-208
(terminal No.4 and 3 <1st squib> or terminal No. 1 and 2
<2nd squib>) in good condition?
YES : Go to Step 7.
NO : Replace the harness wires between SRS-ECU

connector C-37 and clock spring connector C-208.
Then go to Step 7.

STEP 7. 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 B1B01 <1st squib> or B1B05 <2nd squib> set?

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

AC608813

C-37 Harness side
connector (front view)

AZ

<1st squib>

AC608813

C-37 Harness side
connector (front view)

BA

<2nd squib>

SRS AIR BAG DIAGNOSIS

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SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-56

DTC B1B02: Driver's Air Bag Module (1st squib) System (Squib Circuit Open)

DTC B1B06: Driver's Air Bag Module (2nd squib) System (Squib Circuit Open)

CAUTION

If DTCB1B02 <1st squib> or B1B06 <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.

SRS-ECU

CLOCK
SPRING

DRIVER'S AIR BAG
MODULE (SQUIB)

CONNECTOR LOCK SWITCH

CONNECTOR COUPLED: ON

CONNECTOR UNCOUPLED: OFF

NOTE

:

Driver's Air Bag Module (Squib) Circuit

AC708951AC

C-37 (Y)

Connector: C-37

AC708953AB

Connectors: C-204, C-208

C-208 (Y)

C-204 (Y)

SRS AIR BAG DIAGNOSIS

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SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-57

• The ignition signal is input to the air bag module

via the clock spring to inflate the air bag.

.

DTC SET CONDITIONS

• This DTC is set if there is abnormal resistance

between the input terminals of the driver's air bag
module (squib). The most likely causes for this
code to be set are the followings:

• Open circuit in the driver's air bag module

(squib) or harness

• Open circuit in the clock spring

• Malfunction of connector contact

.

TROUBLESHOOTING HINTS

• Open circuit in the clock spring

• Open circuit due to improper neutral position of

the clock spring

• Open circuit in the driver's air bag module (squib)

circuit

• Disengaged driver's air bag module (squib) con-

nector

• 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

• 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

SRS AIR BAG DIAGNOSIS

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SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-58

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

).