Code No.B1412
Passenger’s (front) air bag module (squib) system (shorted to squib
circuit earth)
caution |
- If
the diagnosis code B1412 is set to SRS-ECU, be sure to diagnose the CAN
bus line.
- Follow the diagnosis procedure below. If diagnosis code B1412 is set,
check squib
side circuit.
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Only when the frontal impact exceeding the
threshold is simultaneously detected (turned
ON) by the front impact sensor as well as by the analogue G-sensor and
safing G-sensor in SRS-ECU,
the electric current is supplied from SRS-ECU to the passenger’s
(front) air bag module
(squib).
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The code is set when the SRS-ECU
passenger’s (front) air bag module (squib) circuit
is shorted to earth.
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- Damaged wiring harness and connectors
- Passenger’s (front) air bag module (squib) harness shorted to
earth
- 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 reset.
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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 codes No. B1412 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/ACB04307AB00ENG.png)
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(2)Use the flat-tipped screwdriver to pull out
the locking button of wiring harness side
connector, and release the lock.
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![](../../../img/52/AC306760BA00ENG.png)
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(3)Connect special tool dummy resistor
(MB991865) to special tool resistor harness (MB991866). (4)
caution |
Do not insert a probe directly into the terminal
from the connector
front side as the connector contact pressure may be weakened.
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Insert the resistor harness probe from the back of harness side
connector ASQ+,
ASQ- line. (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 the diagnosis code No. B1412 set?
Go to Step 4.
Replace the passenger’s (front)
air bag module (Refer to ).
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STEP 4. 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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![](../../../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, and
disconnect the SRS-ECU
connector.
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![](../../../img/52/ACB04307AB00ENG.png)
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(3)
danger |
To release the connector short spring in the
following operations,
disconnect this harness side connector, and keep the squib circuit
shorted.
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Use the flat-tipped screwdriver to pull out the locking button of
wiring harness side
connector, and release the lock.
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![](../../../img/52/AC905150AQ00ENG.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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Insert an insulator (width: 3 mm, thickness: 0.5 mm) such as cable
tie between the ASQ+,
ASQ- line, and then release the short spring. (5)Take the measurements
below at the harness side connector.
- Continuity between ASQ+, ASQ- line and body
earth
OK: No continuity
Q.
Is the check result normal?
Go to Step 5.
Repair ASQ+, ASQ- line between
the SRS-ECU connector and the passenger’s
(front) air bag module connector.
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STEP 5. Check whether the diagnosis code is reset.
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Q.
Is the diagnosis code No. B1412 set?
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Replace SRS-ECU (Refer to ).
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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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