U1540

DTC No.U1540 Theft-alarm SNSR. LIN checksum

CAUTION:
Before replacing the ECU or sensor, ensure that the power supply circuit, the ground circuit and the communication circuit are normal.

TROUBLE JUDGMENT

The ETACS-ECU will set diagnostic trouble code No. U1540 when abnormal signals are received from the theft-alarm sensor.

TROUBLESHOOTING HINTS

Faulty theft-alarm sensor

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)

Using scan tool MB991958, read the ETACS-ECU diagnostic trouble code.

Check again if the diagnostic trouble code 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.





(1)Connect scan tool MB991958. Refer to "How to connect the Scan Tool (M.U.T.-III) Reading and Clearing Diagnostic Trouble Codes."
(2)Erase the DTC.
(3)Turn the ignition switch to the "ON" position.
(4)Check if the DTC is set.
(5)Turn the ignition switch to the "LOCK" (OFF) position.

Q. Is the DTC set?

YES Replace the theft-alarm sensor.

NO A poor connection, open circuit, or other intermittent malfunctions in the LIN bus lines between the theft alarm sensor and the ETACS-ECU How to Cope With Intermittent Malfunctions).