Code No.B1489: Passenger’s air bag off indicator lamp drive circuit system fault 1 (Lamp does not Illuminate).
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If diagnosis code B1489 is set in the SRS-ECU, always diagnose the CAN main bus line.
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OPERATION
- Power for the passenger’s air bag off indicator lamp is supplied from the ignition switch (IG1).
- The passenger’s air bag off indicator lamp illuminates when the ignition switch is turned to the "ON" position and goes out after approximately 7 seconds if there is not a malfunction in the SRS system.
- If a failure occurs in the system, the SRS-ECU will stop sending that SRS warning lamp "OFF" signal, thus causing the combination meter to illuminate the SRS warning lamp.
- The SRS warning lamp "OFF" signal is not sent to the combination meter in the cases below, either. Therefore, the combination meter will illuminate the SRS warning lamp.
- The SRS-ECU connector is disconnected.
- The SRS-ECU is not working normally due to a failure in its power supply lines.
- The wiring harness between the passenger’s air bag off indicator lamp and the SRS-ECU is broken.
DIAGNOSIS CODE SET CONDITIONS
This diagnosis code will be set if the passenger’s air bag off indicator lamp driving circuit is short to earth. If the vehicle condition returns to normal, diagnosis code B1489 will be automatically erased, and the warning lamp will go out.
PROBABLE CAUSES
- Damaged wiring harnesses or connectors
- Malfunction of the SRS-ECU
- Malfunction of the passenger’s air bag off indicator lamp
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STEP 1. M.U.T.-III CAN bus diagnostics
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Use the 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 54D, Diagnosis  ).
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STEP 2. Check whether the diagnosis code is reset.
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Check again if the diagnosis code is set.
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(1)Erase the diagnosis code.
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(2)Ignition: "LOCK" (OFF) position to "ON"
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(3)On completion, check that the diagnosis code is not reset.
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Q.
Is the diagnosis code set?
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Go to Step 3 .
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There is an intermittent malfunction such as poor engaged connector(s) or open circuit (Refer to GROUP 00, How to Cope with Intermittent Malfunction ).
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STEP 3. M.U.T.-III diagnosis code
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| caution |
To prevent damage to M.U.T.-III MB991958, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting M.U.T.-III MB991958.
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(1)Turn the ignition switch to the "ON" position.
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(2)Check if the diagnosis code is set.
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(3)Turn the ignition switch to the "LOOK" (OFF) position.
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Q.
Is diagnosis code B1570, B1571, B1572, B1573, B1574, B1575, B1576, B1577, B1578, B1579 or B1581 set?
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Carry out the troubleshooting of the passenger’s air bag cut off switch system. (Refer to ).
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Go to Step 4 .
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STEP 4. Check the passenger’s air bag off indicator lamp connector C-25.
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Q.
Is the connector correctly engaged?
Go to Step 5 .
Engage the connector correctly. Then go to Step 10 .
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STEP 5. Voltage measurement at passenger’s air bag off indicator lamp connector C-25.
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(1)Disconnect passenger’s air bag off indicator lamp connector C-25.
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(2)Measure the voltage between C-25 harness side connector terminal 1 and body earth.
OK: Approximately 12 volt
Q.
Is the check result normal?
Go to Step 7 .
Go to Step 6 .
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STEP 6. Check the harness for short circuit between ignition switch connector C-307 (terminal No.2) and passenger’s air bag off indicator lamp C-25 (terminal No.1).
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| note |
After inspecting intermediate connectors C-202, C-01 and C-205 inspect the wiring harness. If intermediate connectors C-202, C-01 and C-205 are damaged, repair or replace them. Then go to Step 10 .
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Q.
Are the harness wires between passenger’s air bag off indicator lamp connector C-25 (terminal No.1) and the ignition switch connector C-307 (terminal No.2) in good condition?
Go to Step 7 .
Repair the harness wires. Then go to Step 10 .
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STEP 7. Connector check SRS-ECU connector C-119.
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Q.
Is SRS-ECU connector C-119 good condition?
Go to Step 8 .
Engage the connector correctly. Then go to Step 10 .
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STEP 8. Check the harness for short circuit between passenger’s air bag off indicator lamp C-25 (terminal No.3) and SRS-ECU connector C-119 (terminal No.21).
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Q.
Are the harness wires between SRS-ECU connector C-119 (terminal No.21) and the passenger’s air bag off indicator lamp C-25 (terminal No.3) in good condition?
Go to Step 9 .
Repair the harness wires. Then go to Step 10 .
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STEP 9. Check the passenger’s air bag off indicator lamp.
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(1)Disconnect the negative battery terminal.
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(2)Disconnected the SRS-ECU connector C-119, and measure at the wiring harness side.
(3)Connect the negative battery terminal.
(4)Turn the ignition switch to the "ON" position.
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(5)
| 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 terminal No.21 to earth.
Q.
Does the indicator lamp illuminate?
Erase the diagnosis code memory, and check the diagnosis code. If diagnosis code B1489 set, replace the SRS-ECU. (Refer to ). Go to Step 10
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Replace the passenger’s air bag off indicator lamp (Refer to GROUP 52A, Instrument Panel Assembly ). Go to Step 10 .
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STEP 10. Check whether the diagnosis code is reset.
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Q.
Is diagnosis code B1489 set?
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Return to Step 1 .
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The procedure is complete (If no malfunctions are found in all steps, an intermittent malfunction is suspected). Refer to GROUP 00, How to Use Troubleshooting/Inspection Service Points .
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