Inspection Procedure 4: The security alarm horn does not sound while the security alarm Is triggered. <Vehicles without security alarm sensor>


caution
  • Before replacing the ECU, ensure that the power supply circuit, the earth circuit and the communication circuit are normal.
  • When the ETACS-ECU of vehicles without KOS is replaced, the encrypted code of the ignition key needs to be registered to the ETACS-ECU. (If the encrypted code is not registered, the engine cannot be started. Register the encrypted code as described in Immobilizer System - How to Register Key ID .)

COMMENTS ON TROUBLE SYMPTOM


If the security alarm horn does not sound, the security alarm horn input signal circuit or the ETACS-ECU may be defective.

PROBABLE CAUSES



DIAGNOSIS PROCEDURE

STEP 1. M.U.T.-III diagnosis code
Check if diagnosis code is set to the ETACS-ECU.

Q. Is the diagnosis code set?
Troubleshoot the ETACS-ECU. Refer to .
Go to Step 2.

STEP 2. Security alarm horn relay check
Refer to .

Q. Is the check result normal?
Go to Step 3.
Replace the security alarm horn relay.

STEP 3. Voltage measurement at the security alarm horn relay connector
(1)Remove the relay, and measure at the relay box side.
(2)Measure the voltage between the security alarm horn relay connector (power supply terminal) and the body earth.
OK: System voltage

Q. Is the check result normal?
Go to Step 5
Go to Step 4

STEP 4. Check of open circuit in power supply line between the fusible link and security alarm horn relay connector.

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 connector(s) or wiring harness.

STEP 5. Check the security alarm horn work normally.

Connect the battery as shown, and verify that the security alarm horn sounds.

Q. Does the security alarm horn work normally?

Go to Step 6.

Replace the security alarm horn, and go to step 6.

STEP 6. Check of open circuit in power supply line between the security alarm horn relay connector and security alarm horn connector.

Q. Is the check result normal?
Go to Step 7.
Repair the connector(s) or wiring harness.

STEP 7. Check of open circuit in HORN line between the security alarm horn relay connector and ETACS-ECU connector.

Q. Is the check result normal?
Go to Step 8.
Repair the connector(s) or wiring harness.

STEP 8. Retest the security alarm system.
Check that the security alarm works normally.

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