Mitsubishi Grandis. Manual — part 1017
TROUBLESHOOTING
SUPPLEMENTAL RESTRAINT SYSTEM (SRS)
52B-120
Code No.B1452: Curtain air bag module (squib) (LH) system (short-circuited to the earth)
CAUTION
If diagnosis code B1452 is set in the SRS-ECU,
always diagnose the CAN main bus line.
OPERATION
The SRS-ECU judges how severe a collision is by
detecting signals from the side impact sensors and
the side air bag safing G-sensor. If the impact is over
a predetermined level, the SRS-ECU outputs an
ignition signal. At this time, if the side air bag safing
G-sensor is on, the curtain air bag module will
deploy.
DIAGNOSIS CODE SET CONDITIONS
This diagnosis code is set if the curtain air bag
module squib (LH) wire(s) are short-circuited to the
earth.
PROBABLE CAUSES
• Damaged wiring harnesses or connectors
• Short to the earth in the curtain air bag module
(squib) (LH) harness
• Malfunction of the SRS-ECU
DIAGNOSTIC PROCEDURE
STEP 1. MUT-III CAN bus diagnostics
Use the MUT-III to diagnose the CAN bus lines.
Q: Is the check result normal?
YES :
Go to Step 2.
NO :
Repair the CAN bus line (Refer to GROUP
54D, Diagnosis
Wire colour code
B : Black LG : Light green G : Green L : Blue W : White Y : Yellow SB : Sky blue
BR : Brown O : Orange GR : Gray R : Red P : Pink V : Violet
SRS-ECU
CONNECTOR
LOCK SWITCH
CONNECTOR
LOCK SWITCH
: CONNECTOR
CONNECTED: ON
CONNECTOR
DISCONNECTED: OFF
NOTE
CURTAIN AIR BAG
MODULE
(SQUIB) (LH)
Curtain Air Bag Module (Squib) (LH) Circuit
TROUBLESHOOTING
SUPPLEMENTAL RESTRAINT SYSTEM (SRS)
52B-121
STEP 2. Check whether the diagnosis code is
reset.
Check again if the diagnosis code is set.
(1) Erase the diagnosis code.
(2) Ignition: LOCK (OFF) position to ON
(3) On completion, check that the diagnosis code is
not reset.
Q: Is the diagnosis code 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
STEP 3. Check the curtain air bag module (LH).
(MUT-III diagnosis code.)
(1) Disconnect the negative battery terminal.
(2) Disconnect the intermediate connector G-22
(connection between rear floor harness and floor
harness).
(3) Connect special tool dummy resistor (MB991865)
to special tool resistor harness (MB991866).
CAUTION
Do not insert a test probe into the terminal from
its front side directly as the connector contact
pressure may be weakened.
(4) Insert special tool resistor harness probe into
floor harness side connector G-22 by
backprobing.
(5) Connect the negative battery terminal.
(6) Erase diagnosis code memory, and check the
diagnosis code.
Q: Is diagnosis code B1452 set?
YES :
Go to Step 4.
NO :
Go to Step 5.
STEP 4. Check the curtain air bag module (LH)
circuit. Resistance measurement at the SRS-ECU
connector C-120.
(1) Disconnect SRS-ECU connector C-120.
(2) Disconnect the intermediate connector G-22
(connection between rear floor harness and floor
harness).
CAUTION
Do not insert a test probe into the terminal from
its front side directly as the connector contact
pressure may be weakened.
(3) Resistance measurement between C-120
harness side connector terminals 5, 6 and body
AC302576AE
G-22 (R)
Connector: G-22
Floor harness
side (front view)
Third seat
belt (LH)
Second seat
belt (LH)
2 1
AC006042CA
MB991866
(Resistor harness)
G-22 Floor harness
connector
G-22 Rear floor
harness connector
MB991865
(Dummy resistor : 3
ΩΩ
AC311438 AE
C-120 (Y)
Connector: C-120
Harness side
(front view)
AC302576AE
G-22 (R)
Connector: G-22
Floor harness
side (front view)
Third seat
belt (LH)
Second seat
belt (LH)
2 1
AC301563
A
B
18
10
15
7
13
5
14
6
16
8
17
9
19
11
20
12
1 2
3 4
AC
C-120
Harness side
connector
(rear view)
TROUBLESHOOTING
SUPPLEMENTAL RESTRAINT SYSTEM (SRS)
52B-122
earth.
OK: Open circuit
Q: Is the check result normal?
YES :
Go to Step 6.
NO :
Repair the harness wire between SRS-ECU
connector C-120 (terminal No.5 and 6) and
intermediate connector G-22 (floor harness
side, terminal No.1 and 2).
STEP 5. Check the curtain air bag module (LH)
circuit. Resistance measurement at the
intermediate connector G-22.
(1) Disconnect the intermediate connector G-22
(connection between rear floor harness and floor
harness).
(2) Disconnect curtain air bag module (LH)
connector G-01. 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.
CAUTION
Do not insert a test probe into the terminal from
its front side directly as the connector contact
pressure may be weakened.
(3) Resistance measurement between G-22 rear
floor harness side connector terminals 1, 2 and
body earth.
OK: Open circuit
Q: Is the check result normal?
YES :
Replace the curtain air bag module (LH)
(Refer to
).
NO :
Repair the harness wire between
intermediate connector G-22 (terminal No.1
and 2) and curtain air bag module (LH)
connector G-01 (terminal No.1 and 2).
STEP 6. Check whether the diagnosis code is
reset.
Q: Is diagnosis code B1452 set?
YES :
Replace the SRS-ECU (Refer to
NO :
An intermittent malfunction is suspected
(Refer to GROUP 00, How to Use
Troubleshooting/Inspection Service Points
).
AC302576AE
G-22 (R)
Connector: G-22
Floor harness
side (front view)
Third seat
belt (LH)
Second seat
belt (LH)
2 1
AC303223
AC
G-01 (B)
Connector: G-01
Harness side
(front view)
Roof centre duct
AC208384AN
G-01
Curtain air bag
module connector
Flat-tip screw
driver
Locking button
G-01
Harness side
connector
AC303710
2
1
AC
G-22 Rear floor harness
connector (rear view)
TROUBLESHOOTING
SUPPLEMENTAL RESTRAINT SYSTEM (SRS)
52B-123
Code No.B1453: Curtain air bag module (squib) (LH) system (short-circuited to the power supply)
CAUTION
If diagnosis code B1453 is set in the SRS-ECU,
always diagnose the CAN main bus line.
OPERATION
The SRS-ECU judges how severe a collision is by
detecting signals from the side impact sensors and
the side air bag safing G-sensor. If the impact is over
a predetermined level, the SRS-ECU outputs an
ignition signal. At this time, if the side air bag safing
G-sensor is on, the curtain air bag module will
deploy.
DIAGNOSIS CODE SET CONDITIONS
This diagnosis code is set if the curtain air bag
module squib (LH) wire(s) are short-circuited to the
power supply.
PROBABLE CAUSES
• Damaged wiring harnesses or connectors
• Short to the power supply in the curtain air bag
module (squib) (LH) harness
• Malfunction of the SRS-ECU
DIAGNOSIS PROCEDURE
STEP 1. MUT-III CAN bus diagnostics
Use the MUT-III to diagnose the CAN bus lines.
Q: Is the check result normal?
YES :
Go to Step 2.
NO :
Repair the CAN bus line (Refer to GROUP
54D, Diagnosis
Wire colour code
B : Black LG : Light green G : Green L : Blue W : White Y : Yellow SB : Sky blue
BR : Brown O : Orange GR : Gray R : Red P : Pink V : Violet
SRS-ECU
CONNECTOR
LOCK SWITCH
CONNECTOR
LOCK SWITCH
: CONNECTOR
CONNECTED: ON
CONNECTOR
DISCONNECTED: OFF
NOTE
CURTAIN AIR BAG
MODULE
(SQUIB) (LH)
Curtain Air Bag Module (Squib) (LH) Circuit
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