Inspection Procedure C-6: The Seat Belt Switch Signal is not Received. <L.H. drive vehicles>


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


COMMENTS ON TROUBLE SYMPTOM


Input signal from the seat belt switch is used to operate the functions below. If the signal is abnormal, these functions will not work normally.

PROBABLE CAUSES



DIAGNOSIS PROCEDURE

STEP 1. Connector check: D-25 seat belt switch (LH) connector or D-26 seat belt switch (RH) connector

Q. Is the check result normal?

Go to Step 2.

Repair the defective connector.

STEP 2. Check the seat belt switch.
Refer to GROUP 52 - Front Seat Belt .

Q. Is the check result normal?
Go to Step 3.
Replace the seat belt switch.

STEP 3. Resistance measurement at the D-25 seat belt switch (LH) connector or D-26 seat belt switch (RH) connector.

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

(2)Check the resistance between the seat belt switch connector and body earth.

  • Resistance between D-25 seat belt switch (LH) connector terminal No.2 and body earth
  • Resistance between D-26 seat belt switch (RH) connector terminal No.2 and body earth
OK: Continuity exists (2 Ω or less)

Q. Is the check result normal?

Go to Step 5.

Go to Step 4.

STEP 4. Check the wiring harness between D-25 seat belt switch (LH) connector or D-26 seat belt switch (RH) connector terminal No.2 and the body earth.


  • Check the earth wires for open circuit.

Q. Is the check result normal?

The trouble can be an intermittent malfunction (Refer to GROUP 00 - How to use Troubleshooting/inspection Service Points - How to Cope with Intermittent Malfunction ).

Repair the wiring harness.

STEP 5. Connector check: C-219 ETACS-ECU connector


Q. Is the check result normal?

Go to Step 6.

Repair the defective connector.

STEP 6. Check the wiring harness between C-219 ETACS-ECU connector terminal No.60 <seat belt switch (RH)> or No.66 <seat belt switch (LH)> and D-25 seat belt switch (LH) connector or D-26 seat belt switch (RH) connector terminal No.1.





note Prior to the wiring harness inspection, check intermediate connector C-15, and repair if necessary.

  • Check the input line for open circuit.

Q. Is the check result normal?

Go to Step 7.

Repair the wiring harness.

STEP 7. M.U.T.-III data list
Check the input signals from the seat belt switch.

  • Remove the each inserted seatbelt.
Item No.
 Item name
 Normal condition
50
 Driver’s seatbelt(Buckle SW)
 Being turned ON from OFF
51
 Passenger seatbelt(Buckle SW)
OK: Normal condition is displayed.

Q. Is the check result normal?
The trouble can be an intermittent malfunction (Refer to GROUP 00 - How to use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunction ).
Replace the ETACS-ECU.