Inspection Procedure B-3

INSPECTION PROCEDURE B-3: Tone Alarm: Seat belt tone alarm function does not work normally.

NOTE: This troubleshooting procedure requires the use of scan tool MB991958 and SWS monitor kit MB991813. For details on how to use the SWS monitor, refer to "How to use SWS monitor."

Seat Belt Tone Alram Function:

CIRCUIT OPERATION
The ETACS-ECU operates the seat belt tone alarm function intermittently according to signals from the following switches:
- Ignition switch (IG1): ON
- Seat belt buckle switch (driver's side): ON

The ETACS-ECU operates the seat belt tone alarm function intermittently under the following conditions:
- Ignition switch: ON or START
- Driver's seat belt: UNFASTENED

TECHNICAL DESCRIPTION (COMMENT)
If the function does not work normally, the input circuit system from the switches or the ETACS-ECU may be defective (refer to CIRCUIT OPERATION").

TROUBLESHOOTING HINTS
- The seat belt buckle switch (driver's side) may be defective
- The ETACS-ECU may be defective
- The wiring harness or connectors may have loose, corroded, or damaged terminals, or terminals pushed back in the connector

DIAGNOSIS

Required Special Tools:
- MB991223: Harness Set
- MB991958: Scan Tool (MUT-III Sub Assembly)
- MB991824: Vehicle Communication Interface (V.C.I.)
- MB991827: MUT-III USB Cable
- MB991911: MUT-III Main Harness B
- MB991813: SWS Monitor Kit
- MB991806: SWS Monitor Cartridge
- MB991812: SWS Monitor Harness (For Column-ECU)
- MB991822: Probe Harness

STEP 1. Use scan tool MB991958 to select "ECU COMM CHK" on the SWS monitor display.

Check 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 the DLC harness before connecting the column-ECU harness. Be sure to connect SWS monitor kit MB991813 after turning on scan tool MB991958.







1. Connect scan tool MB991958 to the data link connector.
2. Connect SWS monitor kit MB991813 to the column switch connector.
3. When the ignition switch is turned to the "ON" position.
4. Operate scan tool MB991958 according to the procedure below to display "ECU COMM CHK."
a. Select "SYSTEM SELECT."
b. Select "SWS."
c. Select "SWS MONITOR."
d. Select "ECU COMM CHK."
5. Scan tool MB991958 should show "OK" on the "ECU COMM CHK" menu for the "ETACS ECU" menu.

Q: Is "OK" displayed on the "ETACS ECU" menu?

YES: Go to Step 2.

NO: Refer to Inspection Procedure A-3 "Communication with ETACS-ECU is not possible."

STEP 2. Check the input signal by using "DATA LIST" menu of the SWS monitor.

Turn the ignition switch to the "ON" position before checking input signals from the ignition switch (IG1).







1. Operate scan tool MB991958 according to the procedure below to display "ETACS ECU."
a. Select "SYSTEM SELECT."
b. Select "SWS."
c. Select "SWS MONITOR."
d. Select "DATA LIST."
e. Select "ETACS ECU."




2. Check that normal conditions are displayed on the items described in the table.

Q: Is normal condition displayed on the "IG SW (IG1)"?

YES: Go to Step 3.

NO: Refer to Inspection Procedure M-2 "ETACS-ECU does not receive any signal from the ignition switch (IG1)."

STEP 3. Check the input signal (by using the Pulse check mode of the monitor).

Check input signal from the seat belt buckle switch (driver's side).




1. Operate scan tool MB991958 according to the procedure below to display "PULSE CHECK."
a. Select "SYSTEM SELECT."
b. Select "SWS."
c. Select "PULSE CHECK."
2. When the driver's seat belt is unfastened, check if scan tool MB991958 sounds or not.

Q: Does scan tool MB991958 sound when the driver's side seat belt is unfastened?

YES: Replace the ETACS-ECU. Verify that the seat belt tone alarm function works normally.

NO: Refer to Inspection Procedure N-3 "ETACS-ECU does not receive any signal from the seat belt buckle switch (driver's side)."