Code No. B1451 Left front curtain air bag module (squib) system (open
circuit of squib circuit) <Vehicles with rear curtain air
bag>
caution |
If diagnosis code No. B1451 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 electric current is supplied from SRS-ECU to the
front curtain air bag module (squib) of impacted side.
TROUBLE JUDGEMENT
The code is set when the open circuit occurs to
the SRS-ECU front curtain air bag module (squib) circuit.
PROBABLE CAUSES
- Open circuit to the front curtain air bag module (squib) circuit
- Damaged connector(s)
- Malfunction of SRS-ECU
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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. B1451 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. 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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![](../../../img/52/AC904706AC00ENG.png)
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(2)Use the flat-tipped screwdriver to pull out
the locking button of front curtain air bag module connector to the
direction of the arrow. After releasing the lock, disconnect the
connector.
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![](../../../img/52/AC301553DQ00ENG.png)
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(3)Connect the dummy resistor (Special tool:
MB991865) to the resistor harness (Special tool: MB991884). (4)Connect
the resistor harness (special tool) to left front curtain air bag module
connector. (5)Connect the negative battery terminal. (6)After erasing
the diagnosis code memory, check the diagnosis code again. (7)Disconnect
the negative battery terminal.
Q.
Is diagnosis code No. B1451 set?
Go to Step 4.
Replace the left front curtain air bag
module.
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STEP 4. Resistance measurement at the SRS-ECU connector and the left
front 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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![](../../../img/52/AC905015AC00ENG.png)
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(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. After disconnect the SRS-ECU
connector.
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![](../../../img/52/AC904706AC00ENG.png)
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(3)
danger |
To release SRS-ECU wiring harness side connector
short spring in the following operations, disconnect front 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
left front curtain air bag module connector to the direction of the arrow.
After releasing the lock, disconnect the connector.
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![](../../../img/52/AC905150BK00ENG.png)
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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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Take the measurements below at the SRS-ECU connector and left front
curtain air bag module connector harness side
connectors.
- Continuity CLS- line between the SRS-ECU connector and the left front
curtain air bag module connector.
- Continuity CLS+ line between the SRS-ECU connector and the left
front curtain air bag module connector.
OK: Continuity (less than 2 Ω)
Q.
Is the check result normal?
Go to Step 5.
Repair the wiring
harness.
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STEP 5. Check whether the diagnosis code is set again.
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Q.
Is diagnosis code No. B1451 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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