Code No. B1450:
Left curtain air bag module (squib) system (short circuit between
squib circuit terminals)
| caution |
If diagnosis code No. B1450
is set in the SRS-ECU, be sure to diagnose the CAN bus
line.
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OPERATION
In case of side collision, when the impact
exceeding the threshold is applied to the vehicle,
and when the impact is simultaneously detected (turned ON) by the side
impact sensor as well
as by the analogue G-sensor in SRS-ECU, the ignition signal is sent from
SRS-ECU to the curtain
air bag module (squib) of impacted side.
TROUBLE JUDGEMENT
The code is set when the short circuit
occurs between the terminals of SRS-ECU curtain
air bag module (squib) circuit.
PROBABLE CAUSES
- Damaged short spring *
- Short circuit between terminals of curtain air bag module
(squib) circuit
- Damaged connector(s)
- Malfunction of SRS-ECU
| note |
*: The squib circuit connectors
integrate a short spring (which prevents the
air bags from being unintentionally deployed because of
static electricity by shorting the positive
wire to the earth wire in the squib circuit when the
connectors are disconnected). Therefore,
when the above codes are set, the short spring may not be
released due to the damaged connector
even when the connectors are connected.
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STEP 1. M.U.T.-III CAN bus diagnostics
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Use M.U.T.-III to diagnose the CAN
bus lines.
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Q.
Is the check result normal?
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 Go to Step
2.
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 Repair the CAN bus
line (Refer to GROUP 54C - Troubleshooting).
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STEP 2. Check whether the diagnosis code is set
again.
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(1)Connect the negative battery terminal.
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(2)After erasing the diagnosis code memory, check
the diagnosis code again.
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(3)Disconnect the negative battery
terminal.
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Q.
Is diagnosis code No. B1450 set?
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Go to Step
3.
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Intermittent
malfunction (Refer to GROUP 00 - How to Use
Troubleshooting/Inspection
Service Points - How to Cope with Intermittent
Malfunction).
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STEP 3. Connector check: SRS-ECU, left curtain air bag
module connector
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(1)Check that the negative battery terminal is
disconnected. If the negative battery
terminal is connected, disconnect it.
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(2)After disconnecting the SRS-ECU connector,
connect it again.
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(3)After disconnecting the left
curtain air bag module harness side connector, connect the
connector again. For the left curtain air bag module
connector disconnection, use the flat-tipped
screwdriver to pull out the harness side connector locking
button. After releasing the lock, disconnect
the connector.
(4)Connect the negative battery
terminal.
(5)After erasing the diagnosis code memory,
check the diagnosis code again.
(6)Disconnect the
negative battery terminal.
Q.
Is diagnosis code No. B1450 set?
Go to Step
4.
Replace
the connector concerned.
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STEP 4. Diagnosis check by dummy resistor connection
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(1)Check that the negative battery terminal is
disconnected. If the negative battery
terminal is connected, disconnect it.
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(2)Use the flat-tipped screwdriver
to pull out the locking button of harness side connector.
After releasing the lock, disconnect the left curtain air
bag module harness side connector.
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(3)Connect special tool dummy
resistor (MB991865) to special tool resistor harness
(MB991884).
(4)Connect special tool resistor harness
(MB991884) to left curtain air bag module
connector.
(5)Connect the negative battery
terminal.
(6)After erasing the diagnosis code memory,
check the diagnosis code again.
Q.
Is diagnosis code No. B1450 set?
Go to Step
5.
Replace
the left curtain air bag module.
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STEP 5. Resistance measurement at the SRS-ECU
connector
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(1)Check that the negative battery terminal is
disconnected. If the negative battery
terminal is connected, disconnect it.
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(2)Disconnect the SRS-ECU connector.
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(3)
| danger |
To release SRS-ECU wiring
harness side connector short spring in the
following operations, disconnect curtain air bag
module connector in advance, and keep the squib
circuit shorted.
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Use the flat-tipped screwdriver to pull out the
locking button of harness side connector.
After releasing the lock, disconnect the left curtain air
bag module harness side connector
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(4)
| caution |
The short spring may not be
released due to the insufficient insertion.
Therefore, insert
the insulator for 4 mm or more.
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Insert an insulator (width: 3 mm, thickness: 0.5 mm)
such as cable tie between the CLS+,
CLS- line and the short spring, and release the short
spring.
(5)Check the continuity between the SRS-ECU
wiring harness side connector CLS+,
CLS- line.
OK: No continuity
Q.
Is the check result normal?
Go to Step
6.
Repair
the wiring harness.
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STEP 6. Check whether the diagnosis code is set
again.
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Q.
Is diagnosis code No. B1450 set?
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Replace
SRS-ECU.
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Intermittent
Malfunction (Refer to GROUP 00 - How to Use
Troubleshooting/Inspection
Service Points - How to Cope with Intermittent
Malfunction).
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