Light Does Not Illuminate

DTC B1487: Passenger Seat Belt Warning Light Drive Circuit System Fault 1 (Light does not Illuminate).

Seat Belt Warning Light Drive Circuit [Vehicles With Halogen Type Headlight]:

Seat Belt Warning Light Drive Circuit [Vehicles With Discharge Type Headlight] (Part 1):

Seat Belt Warning Light Drive Circuit [Vehicles With Discharge Type Headlight] (Part 2):

CAUTION: If DTC B1487 is set in the SRS-ECU, always diagnose the CAN main bus line.

CIRCUIT OPERATION
- Power for the passenger seat belt warning light is supplied from the ignition switch (IG1).
- The passenger seat belt warning light illuminates when the ignition switch is turned to the "ON" position and goes out after approximately seven 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 light "OFF" signal, thus causing the combination meter to illuminate the SRS warning light.
- The SRS warning light "OFF" signal is not sent to the combination meter in the cases below, either. Therefore, the combination meter will illuminate the SRS warning light.
- 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 seat belt warning light and the SRS-ECU is broken.

DTC SET CONDITIONS
This DTC will be set if the passenger seat belt warning light driving circuit is short to ground.

TROUBLESHOOTING HINTS
- Damaged wiring harnesses or connectors
- Malfunction of the SRS-ECU
- Malfunction of the passenger seat belt warning light

DIAGNOSIS

Required Special Tools:
- MB991958: Scan Tool (M.U.T.-III Sub Assembly)
- MB991824: V.C.I.
- MB991827: M.U.T.-III USB Cable
- MB991910: M.U.T.-III Main Harness A

STEP 1. Using scan tool MB991958, diagnose the CAN bus line.

CAUTION: To prevent damage to scan tool MB991958, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991958.

1. Connect scan tool MB991958. Refer to "How to connect the scan tool". How To Connect The Scan Tool (M.U.T.-III)
2. Turn the ignition switch to the "ON" position.
3. Diagnose the CAN bus line.
4. Turn the ignition switch to the "LOCK" (OFF) position.

Q: Is the CAN bus line found to be normal?

YES : Go to Step 2.

NO : Repair the CAN bus line.

STEP 2. Recheck for diagnostic trouble code.

Check again if the DTC is set.

1. Erase the DTC.
2. Turn the ignition switch to the "ON" position.
3. Check if the DTC is set.
4. Turn the ignition switch to the "LOCK" (OFF) position.

Q: Is the DTC set?

YES : Go to Step 3.

NO : There is an intermittent malfunction such as poor engaged connector(s) or open circuit.

STEP 3. Using scan tool MB991958, read the diagnostic trouble code.

1. Turn the ignition switch to the "ON" position.
2. Check if the DTC is set.
3. Turn the ignition switch to the "LOCK (OFF)" position.

Q: Is DTC B1530, B1531, B1532, B1533, B1534, B1535, B1536, B1537, B1538, B1539, B1540, B1541, B1542, B1543, B1545 or B1546 set?

YES : Carry out the troubleshooting of the passenger seat belt switch system, the occupant classification-ECU or the occupant classification sensor system (Refer to [B1530,B1531, B1532, B1533, B1534, B1535, B1536, B1537, B1538 or B1539], [B1540,B1541, B1542 or B1543] or [B1545 or B1546]).

NO : Go to Step 4.

STEP 4. Check the passenger seat belt warning light connector C-07.

Q: Is the connector correctly engaged?

YES : Go to Step 5.

NO : Engage the connector correctly. Then go to Step 10.

STEP 5. Measure the voltage at passenger seat belt warning light connector C-07.

1. Disconnect passenger seat belt warning light connector C-07.

2. Measure the voltage between C-07 harness side connector terminal 1 and body ground.
Voltage should measure approximately 12 volt.

Q: Is the check result satisfactory?

YES : Go to Step 7.

NO : Go to Step 6.

STEP 6. Check the harness for short circuit between ignition switch (IG1) and passenger seat belt warning light C-07 (terminal No.1).

NOTE: After inspecting intermediate connectors C-202 and C-215 inspect the wiring harness. If intermediate connectors C-202 and C-215 are damaged, repair or replace them. Then go to Step 10.

Q: Are the harness wires between passenger seat belt warning light connector C-07 (terminal No.1) and the ignition switch connector (IG1) in good condition?

YES : Go to Step 7.

NO : Repair the harness wires. Then go to Step 10.

STEP 7. Check SRS-ECU connector C-123.

Q: Is the connector correctly engaged?

YES : Go to Step 8.

NO : Engage the connector correctly. Then go to Step 10.

STEP 8. Check the harness for short circuit between passenger seat belt warning light C-07 (terminal No.3) and SRS-ECU connector C-123 (terminal No.42).

Q: Are the harness wires between SRS-ECU connector C-123 (terminal No.42) and the passenger seat belt warning light C-07 (terminal No.3) in good condition?

YES : Go to Step 9.

NO : Repair the harness wires. Then go to Step 10.

STEP 9. Check the passenger seat belt warning light.

1. Disconnect the negative battery terminal.

2. Disconnected the SRS-ECU connector C-123, and measure at the wiring harness side.

3. Connect the negative battery terminal.
4. Turn the ignition switch to the "ON" position.

CAUTION: Do not insert a test probe into the terminal from its front side directly, as the connector contact pressure may be weakened.

5. Connect terminal No.42 to ground.

Q: Does the warning light illuminate?

YES : Erase the diagnostic trouble code memory, and check the diagnostic trouble code. If DTC B1487 set, replace the SRS-ECU. Then go to Step 10.

NO : Replace the passenger seat belt warning light. Then go to Step 10.

STEP 10. Recheck for diagnostic trouble code.