Inspection Procedure B-1

Tone Alarm: Ignition key reminder tone alarm function does not work normally

Ignition Key Reminder Tone Alarm Function:

NOTE: This troubleshooting requires use of scan tool MB991502 and SWS monitor kit MB991862. For details of how to use the SWS monitor, refer to "How to use SWS monitor".

CIRCUIT OPERATION
The ETACS-ECU operates the ignition key reminder tone alarm function (sounds the tone alarm intermittently), 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 (sounds the tone alarm intermittently) if any of the following conditions are satisfied:
- ignition switch : LOCK position (key inserted)
- Driver's door: OPEN

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: Test Harness Set
- MB991502: Scan Tool (MUT-II)
- MB991862: SWS monitor kit







STEP 1. Use scan tool to select "ECU CHECK" on the SWS monitor display.

Check the ETACS-ECU.

CAUTION: To prevent damage to scan tool MB991502, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991502. Also connect SWS monitor kit MB991862 after turning on scan tool MB991502.

1. Connect scan tool MB991502 to the data link connector.
2. Connect SWS monitor kit MB991862 to the column switch connector.
3. When the ignition switch is turned to the "LOCK" (OFF) position, scan tool MB991502 should show "OK" on 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 impossible."

STEP 2. Check the input signal by using service data of the SWS monitor.







Check the input signals from the following switches:
- ignition switch: OFF (key inserted)
- Driver's door: open




Select "BUZZER-KEY REMND. ALM" (FUNCTION DIAG), and check that normal conditions are displayed on the items described in the table above.

Q: Are normal conditions displayed on the "IG SW (IG1)", "FRONT DOOR SW" and "BUZZER"?

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

NO:
- Normal condition is not displayed on the "IG SW (IG1)": Refer to Inspection Procedure L-2 "ETACS-ECU does not receive a signal from the ignition switch (IG1)."
- Normal condition is not displayed on the "FRONT DOOR SW: Refer to Inspection Procedure L-5 "ETACS-ECU does not receive a signal from the driver's or the front passenger's door switch."
- Normal condition is not displayed on the "BUZZER": Go to STEP 3.




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

Check the input signals from the key reminder switch.
- Check whether scan tool MB991502 sounds or not when the ignition key is removed and reinserted.

Q: Does scan tool MB991502 sound when the ignition key is removed and reinserted?

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

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