INSPECTION PROCEDURE P-18: The front passenger’s seat belt switch signal is not received. <Vehicles for Australia and New Zealand>


caution Whenever the ECU is replaced, ensure that the input signal circuit is normal.


COMMENTS ON TROUBLE SYMPTOM
Input signal from the passenger’s seat belt switch is used to operate the seat belt warning buzzer function and seat belt warning lamp. If the signal is abnormal, the seat belt warning buzzer function and seat belt warning lamp will not work normally.

POSSIBLE CAUSES

  • Malfunction of the passenger’s seat belt switch
  • Malfunction of the seat occupancy sensor
  • Malfunction of the ETACS-ECU
  • Damaged harness wires and connectors

DIAGNOSTIC PROCEDURE

Step 1. Connector check: D-23 seat belt switch (LH) connector

Q. Is the check result normal?

Go to Step 2.

Repair the defective connector.

Step 2. Check the seat belt switch (LH).
Refer to GROUP 52A - Front seat belt .

Q. Is the check result normal?
Go to Step 3.
Replace the inner seat belt (front passenger’s side).

Step 3. Connector check: D-23-1 seat occupancy sensor connector

Q. Is the check result normal?

Go to Step 4.

Repair the defective connector.

Step 4. Check the seat occupancy sensor.
Refer to GROUP 52A - Front seat .

Q. Is the check result normal?
Go to Step 5.
Replace the seat occupancy sensor.

Step 5. Measure the resistance at the D-23-1 seat occupancy sensor connector.

(1)Disconnect the connector, and measure at the wiring harness side.

(2)Resistance between D-23-1 seat occupancy sensor connector terminal No.3 and body earth
OK: 2 Ω or less

Q. Is the check result normal?

Go to Step 7.

Go to Step 6.

Step 6. Check the wiring harness between D-23-1 seat occupancy sensor connector terminal No.3 and body earth.


  • Check the earth wires for open circuit.

Q. Is the check result normal?

Replace the inner seat belt (front passenger’s side).

Repair the wiring harness.

Step 7. Connector check: C-220 ETACS-ECU connector

Q. Is the check result normal?

Go to Step 8.

Repair the defective connector.

Step 8. Check the wiring harness from D-23-1 seat occupancy sensor connector terminal No.1 to C-220 ETACS-ECU connector terminal No.29.



note Prior to the wiring harness inspection, check intermediate connector C-16, and repair if necessary.

  • Check the input line for open circuit.

Q. Is the check result normal?

Go to Step 9.

Repair the wiring harness or replace the inner seat belt (front passenger’s side).

Step 9. Retest the system.
Check that the passenger’s seat belt switch signal is received normally.

Q. Is the check result normal?
Intermittent malfunction. (Refer to GROUP 00 - How to Cope with Intermittent Malfunction ).
Replace the ETACS-ECU.