Light Does Not Illuminate

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

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 passenger seat belt warning light "OFF" signal, and illuminates the passenger seat belt warning light.
- The SRS-ECU illuminates the passenger seat belt warning light under the following conditions.
- 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 open.

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.

(1)
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.

Connect scan tool MB991958. Refer to "How to connect the scan tool Reading and Clearing Diagnostic Trouble Codes."
(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 CAN Bus Diagnostics Chart).

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 How to Cope With Intermittent Malfunctions).

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 Perform troubleshooting for DTC that is set. Then go to Step 10.

NO Go to Step 4.

STEP 4. Check the passenger seat belt warning light connector C-07 for loose, corroded or damaged terminals.

Q. Is the passenger seat belt warning light connector C-07 in good condition?

YES Go to Step 5.

NO Repair or replace the connector. Harness Connector Inspection.

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)Turn the ignition switch to the "ON" position.

(3)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 open and 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. Harness Connector Inspection. 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 10.

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.

(3)Connect the negative battery terminal.
(4)Turn the ignition switch to the "ON" position.
(5)
CAUTION:
Do not insert a test probe into the terminal from its front side directly, as the connector contact pressure may be weakened.

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 (Refer to Service and Repair). Then go to Step 10
.

NO Replace the passenger seat belt warning light Removal and Replacement). Then go to Step 10.

STEP 10. Recheck for diagnostic trouble code.