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 MB991502 orMB991958 and SWS monitor kit MB991813. For details on how to use the SWS monitor, refer to "How to use SWS monitor."

Seat Belt Tone Alarm 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
- Driver's seat belt switch: 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
- Trouble in input signal system
- The wiring harness or connectors may have loose, corroded, or damaged terminals, or terminals pushed back in the connector
- The ETACS-ECU may be defective

DIAGNOSIS

Required Special Tools:
- MB991223: Harness Set
- MB991502: Scan Tool (MUT-II)
- MB991496: Main unit
- MB991497: Test Harness (for communication)

- MB991958: Scan Tool (MUT-III Sub Assembly)
- MB991824: V.C.I.
- MB991827: USE Cable
- MB991911: Main Harness B

- MB991813: SWS monitor kit
- MB991806: SWS monitor cartridge
- MB991812: SWS monitor harness (for column-ECU)
- MB991922: Probe harness

STEP 1. Use scan tool MB991502 or MB991958 to select "ECU COMM Check" on the SWS monitor display.
Check the ETACS-ECU.

CAUTION: To prevent damage to scan tool MB991502 or MB991958, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991502 or MB991958. Connect special tool MB991497 or MB991911 before connecting special tool MB991812. Be sure to connect special tool MB991806 after turning on special tool MB991496 or MB991824.










1. Connect the special tool. Refer to "How to connect SWS monitor".
2. Turn the ignition switch to the "ON" position.
3. Operate scan tool MB991502 or MB991958 according to the procedure below to display "ECU COMM Check."
a. Select "Interactive Diagnosis."
b. Select "System select."
c. Select "SWS."
d. Select "SWS MONITOR."
e. Select "ECU COMM Check."

4. Scan tool MB991502 or MB991958 should show "OK" on the "ECU COMM Check" 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 "FUNCTION DIAG." menu of the SWS monitor.
Check the input signals from the following switches:
- Ignition switch: OFF -> ON
- Driver's seat belt: Unfastened
- All door: closed







1. Operate scan tool MB991958 according to the procedure below to display "OTHER ALARM"
a. Select "Interactive Diagnosis."
b. Select "System select."
c. Select "SWS."
d. Select "SWS MONITOR."
e. Select "Function Diag."
f. Select "BUZZER."
g. Select "OTHER ALARM"

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









NOTE: Turn the ignition switch from the OFF position to the ON position. Then item No.43 should be ON for approximately six seconds only.

Q: Does the scan tool MB991502 or MB991958 display the items "IG SW (IG1)" and "BUZZER" as normal condition?

Normal conditions are displayed for all the items: Replace the ETACS-ECU. Verify that the seat belt tone alarm function works normally.

Normal condition is not displayed for "IG SW (IG1)": Refer to Inspection Procedure O-2 "ETACS-ECU does not receive any signal from the ignition switch (IG1)".

Normal condition is not displayed for "BUZZER": Go to Step 3.

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










Check input signal from the driver's side seat belt switch.
- Driver's seat belt: fastened
1. Operate scan tool MB991502 or MB991958 according to the procedure below to display "Pulse check."
a. Select "Interactive Diagnosis."
b. Select "System select."
c. Select "SWS."
d. Select "Pulse Checking."

2. Check scan tool MB991502 or MB991958 sounds when the driver's seat belt is unfastened.

Q: Does scan tool MB991502 or 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 O-3 "ETACS-ECU does not receive a signal from the driver's side seat belt switch".