Code No.B1408:
Front impact sensor (RH) communication error
Code No.B1409: Front impact sensor (RH)
communication impossible
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If diagnosis code No. B1408 or B1409 is stored in the
SRS-ECU, always diagnose the CAN main bus line.
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OPERATION
The front impact sensor transmits acceleration data to the SRS-ECU. The SRS-ECU then determines whether
to operate the front air bags, and then outputs an ignition signal when necessary. The front impact
sensor also diagnoses itself, and sends a diagnosis code to the SRS-ECU if a malfunction occurs
DIAGNOSIS CODE SET CONDITIONS
The diagnosis code is stored if the communication between the right front impact sensor
and SRS-ECU is abnormal (No. B1408), or impossible (No. B1409).
PROBABLE CAUSES
- Damaged wiring harnesses or connectors
- Malfunction of the front impact sensor (RH)
- Malfunction of the 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 stored 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. B1408 or B1409 stored?
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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. Check the front impact sensor (RH).
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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)Alternate the front impact sensor (RH) and front impact sensor (LH), and then install
the alternated sensors.
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(3)Connect the negative battery terminal.
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(4)After erasing the diagnosis code memory, check the diagnosis code again.
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(5)Disconnect the negative battery terminal.
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Q.
Is diagnosis code No. B1408 or B1409 stored?
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Replace the front impact sensor (RH) (Refer to ).
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Go to Step 4.
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STEP 4.Check of short to power supply, short to earth, and open circuit
in FRH-, FRH+ line between SRS-ECU connector and front impact sensor (RH) connector.
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After inspecting intermediate connector inspect the wiring harness. If the intermediate
connector is damaged, repair or replace it.
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Q.
Is the check result normal?
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Go to Step 5.
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Repair the wiring harness.
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STEP 5. Check whether the diagnosis code is stored again.
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Q.
Is diagnosis code No. B1408 or B1409 stored?
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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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