Mitsubishi Evolution X. Manual — part 650
SRS AIR BAG DIAGNOSIS
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SUPPLEMENTAL RESTRAINT SYSTEM (SRS)
52B-47
STEP 5. Check the driver’s air bag module circuit. Measure
the resistance at the SRS-ECU connector C-37.
(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-37 SRS-ECU connector.
DANGER
To prevent the air bag from deploying unintentionally,
disconnect the clock spring connector C-208 to short
the squib circuit.
(3) Disconnect the clock spring connector C-208.
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 5, 6 <1st squib> or 9, 10 <2nd
squib> and the short spring to release the short spring.
AC506734
A
AD
Lock lever
AC507302 BF
A
A
C-37 Harness side
connector (front view)
Section
A - A
Cable tie
Short spring
Terminal
<1st Squib>
4 mm (0.16 inch) or more
AC507302BG
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
SRS AIR BAG DIAGNOSIS
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SUPPLEMENTAL RESTRAINT SYSTEM (SRS)
52B-48
(5) Check for continuity between C-37 harness side connector
terminals 5 and 6 <1st squib> or 9 and 10 <2nd squib> and
body ground.
It should be open circuit.
Q: Is it open circuit?
YES : Erase the diagnostic trouble code memory, and check
the diagnostic trouble code. If DTC B1B00 <1st
squib> or B1B04 <2nd squib> sets, replace the
SRS-ECU (Refer to
NO : Go to Step 6.
STEP 6. Check the harness for short circuit to ground
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 the harness wires 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>) 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 B1B00 <1st squib> or B1B04 <2nd squib> set?
YES : Return to Step 1.
NO : The procedure is complete.
AC608812
C-37 Harness side
connector (front view)
EW
<1st squib>
AC608812
C-37 Harness side
connector (front view)
EX
<2nd squib>
SRS AIR BAG DIAGNOSIS
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SUPPLEMENTAL RESTRAINT SYSTEM (SRS)
52B-49
DTC B1B01: Driver's Air bag Module (1st squib) System (Shorted to Squib Circuit Power Supply)
DTC B1B05: Driver's Air bag Module (2nd squib) System (Shorted to Squib Circuit Power Supply
CAUTION
If DTC B1B01 <1st squib> or B1B05 <2nd squib>
is set in the SRS-ECU, always diagnose the CAN
main bus line.
.
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-50
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
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).
.
TROUBLESHOOTING HINTS
• Malfunction of the clock spring
• Damaged harness wires and connectors
• Short to the power supply in the driver's 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
."
(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,
).
AC608435
Data link connector
MB991827
MB991824
MB991910
AB
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