Inspection Procedure B-1

Tone Alarm: Ignition Key Reminder Tone Alarm Function does not Work Normally.

NOTE: This troubleshooting requires use of scan tool MB991958 and SWS monitor kit MB991862. For details of how to use the SWS monitor, refer to "How to use SWS monitor." How To Use SWS Monitor

Ignition Key Reminder Tone Alarm Function:

CIRCUIT OPERATION
The ETACS-ECU operates the ignition key reminder tone alarm function, based on input signals from the following switches:
- Ignition switch (IG1): OFF
- Key reminder switch: OFF
- Driver's door switch: ON

The ETACS-ECU operates the ignition key reminder tone alarm function under the following conditions:
- Ignition key position: "LOCK" (OFF) or "ACC" position
- Ignition key: Inserted in the ignition key cylinder

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
- Malfunction of the key reminder switch
- Malfunction of front door switches
- Malfunction of the ETACS-ECU
- Damaged harness wires or connectors

DIAGNOSIS

Required Special Tools:
- MB991223: Harness Set
- MB991958: Scan Tool (MUT-III Sub Assembly)
- MB991824: Vehicles communication interface
- 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)
- MB991922: Probe harness

STEP 1. Use scan tool MB991958 to select "ECU COMM Check" 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 special tool MB991911 before connecting special tool MB991812. Be sure to connect special tool MB991806 after turning on special tool MB991824.







1. Connect the special tool. Refer to "How to connect SWS monitor How to Connect SWS Monitor."
2. Turn the ignition switch to the "LOCK" (OFF) position.
3. Operate scan tool 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 MB991958 should show "OK" on the "ECU COMM Check" menus for both the "ETACS ECU" menus.

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 impossible."







STEP 2. Check the input signal by using "FUNCTION DIAG." of the SWS monitor.
Check the input signals from the following switches:
- Ignition switch: OFF (key inserted)
- Driver's door: open
- Front passenger's door: closed

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




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

NOTE: The scan tool display changes when the driver's or the front passenger's door is opened. If any of the doors is open, the system can not be checked correctly.

Q: Does the scan tool display the items "IG SW (IG1)", "FRONT DOOR SW" and "BUZZER" as normal condition?

Normal conditions are displayed for all the items: Replace the ETACS-ECU. The ignition key reminder tone alarm function should work normally.

The scan tool does not show the respective normal condition for item "IG SW (IG1).": Refer to Inspection Procedure O-2 "ETACS-ECU does not receive a signal from the ignition switch (IG1)."

The scan tool does not show the respective normal condition for item "FRONT DOOR SW.": Refer to Inspection Procedure O-6 "ETACS-ECU does not receive a signal from the driver's or the front passenger's door switch."

The scan tool does not show the respective normal condition for item "BUZZER.": Go to Step 3.




STEP 3. Check the input signal (by using the pulse check mode of the monitor).
Check the input signals from the key reminder switch.

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 ignition key is removed.

Q: Does scan tool MB991958 sound when the ignition key is removed?

YES: Replace the ETACS-ECU. The ignition key reminder tone alarm function should work normally.

NO: Refer to Inspection Procedure P-1 "ETACS-ECU does not receive a signal from the key reminder switch."