Inspection Procedure 6
Inspection Procedure 6: Theft-alarm siren does not sound.
CAUTION:
Before replacing the ECU, ensure that the power supply circuit, the ground circuit and the communication circuit are normal.
TECHNICAL DESCRIPTION (COMMENT)
When only the hazard warning light flashes and the theft-alarm siren does not sound during
"Exterior protection" status, the theft-alarm siren may have an internal error or the LIN cutoff control unit may be defective.
TROUBLESHOOTING HINTS
- Theft-alarm siren may be defective
- LIN cutoff control unit may be defective
DIAGNOSIS
Required Special Tools:
- MB991958: Scan Tool (M.U.T.-III Sub Assembly)
- MB991824: Vehicle Communication Interface (V.C.I.)
- MB991827: M.U.T.-III USB Cable
- MB991910: M.U.T.-III Main Harness A (Vehicles with CAN communication system)
STEP 1. Theft-alarm siren operation check
(1)Set the theft-alarm to the "Ready to be triggered" condition.
(2)Open the driver's door by using the ignition key.
(3)Check that the theft-alarm siren sounds.
Q. Is the check result normal?
YES The trouble can be an intermittent malfunction How to Cope With Intermittent Malfunctions).
NO Go to Step 2.
STEP 2. Using scan tool MB991958, read the ETACS-ECU diagnostic trouble code.
Check if DTC is set to the ETACS-ECU.
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 scan tool (M.U.T.-III) Reading and Clearing Diagnostic Trouble Codes."
(1)Turn the ignition switch to the "ON" position.
(2)Check whether the ETACS-ECU DTC is set.
(3)Turn the ignition switch to the "LOCK" (OFF) position.
Q. Is the DTC set?
YES Diagnose the ETACS-ECU (Refer to Electronic Time and Alarm Control System (ETACS)).
NO Go to Step 3.
STEP 3. LIN cutoff control unit check
Check the continuity of the LIN cutoff control unit. (Refer to LIN Cutoff Control Unit Inspection.)
Q. Is the check result normal?
YES Go to Step 4.
NO Replace LIN cutoff control unit.
STEP 4. Theft-alarm siren operation check
(1)Set the theft-alarm to the "Ready to be triggered" condition.
(2)Open the driver's door by using the ignition key.
(3)Check that the theft-alarm siren sounds.
Q. Is the check result normal?
YES The trouble can be an intermittent malfunction How to Cope With Intermittent Malfunctions).
NO Replace the theft-alarm siren.