Code No.4F: Curtain air bag module (squib) (LH) system
(short-circuited to the earth)
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
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STEP 1. Check the diagnosis code by connecting a dummy
resistor (M.U.T.-III diagnosis code).
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(1)Disconnect the negative battery
terminal.
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(2) Disconnect intermediate
connector G-22 (connection between curtain air bag harness
and floor harness).
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(3)Connect special tool dummy
resistor (MB991865) to special tool resistor harness
(MB991866).
(4)
| caution |
Do not insert a test probe
into the terminal from its front side directly
as the connector contact pressure may be
weakened.
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Connect special tool (MB991866) to the G-22 harness
side connector by backprobing.
(5)Connect the negative
battery terminal.
(6)Erase diagnosis code memory, and
check the diagnosis code.
Q.
Is diagnosis code 4F set?
 Go to Step
2.
 Go to Step
3.
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STEP 2. Resistance measurement at the SRS-ECU connector
C-146.
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(1)Disconnect the negative battery
terminal.
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(2)Disconnect SRS-ECU connector
C-146.
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(3) Disconnect intermediate
connector G-22 (connection between curtain air bag harness
and floor harness).
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(4)
| caution |
Do not insert a test probe
into the terminal from its front side directly
as the connector contact pressure may be
weakened.
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Resistance measurement between C-146 harness side
connector terminals27, 28 and body earth.
OK:
Open circuit
Q.
Is the check result normal?
Go to Step
4.
Repair
the harness wire between SRS-ECU connector C-146 (terminal
No.27 and 28) and harness side connector G-22 (terminal
No.1and 2).
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STEP 3. Resistance measurement at the curtain air bag
harness connector G-22.
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(1)Disconnect the negative battery
terminal.
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(2) Disconnect intermediate
connector G-22 (connection between curtain air bag harness
and floor harness).
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(3)Disconnect curtain air bag
harness connector G-01. Use a flat-tipped screwdriver to
pull out the locking button at the harness side connector,
and then disconnect the connector.
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(4)
| caution |
Do not insert a test probe
into the terminal from its front side directly
as the connector contact pressure may be
weakened.
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Resistance measurement between G-22 curtain air bag
module (LH) side connector terminals 1, 2 and body
earth.
OK: Open circuit
Q.
Is the check result normal?
Replace the curtain
air bag module (Refer to ).
Repair the harness
wire between curtain air bag module (LH) connector G-22
(terminal No.1 and 2) and curtain air bag module connector
G-01 (terminal No.1and 2).
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STEP 4. Check whether the diagnosis code is
reset.
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Q.
Is diagnosis code 4F set?
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Replace the SRS-ECU
(Refer to).
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An intermittent
malfunction is suspected (Refer to GROUP 00, How to Use
Troubleshooting/Inspection Service Points ).
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