Inspection Procedure C-6

Central Door Locking System: Forgotten Key Prevention Function does not Work Normally.

Forgotten Key Prevention Function Circuit:

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

CIRCUIT OPERATION
The ETACS-ECU operates the forgotten key prevention function according to the following switches:
- Key reminder switch: OFF
- Driver's or front passenger's door switch: ON
- Driver's or front passenger's door lock actuator switch: being turned on

The ETACS-ECU operates the forgotten key prevention function under the following conditions:
- Ignition key: inserted into the ignition key cylinder
- Driver's or front passenger's door: open
- Driver's or front passenger's door lock: being locked

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 key reminder switch may be defective
- The driver's or passenger's door switch may be defective
- The driver's or passenger's door lock actuator switch 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: Vehicles 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)
- MB991922: 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 special tool MB991910 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 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 the scan tool MB991958 according to the procedure below to display "ETACS ECU."
a. Select "Interactive Diagnosis."
b. Select "System Select."
c. Select "SWS."
d. Select "SWS MONITOR."
e. Select "Data List."
f. Select "ETACS ECU."




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

Q: Does scan tool MB991958 display "FRONT DOOR SW" as normal condition?

YES: Go to Step 3.

NO: Refer to Inspection Procedure O-6 "ETACS-ECU does not receive a signal from the driver's or the front passenger's door switch."

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




1. Operate scan tool 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. If the switches (see table), which are applicable for the input signal check, are operated, check if scan tool MB991958 sounds or not.

Q: Does scan tool MB991958 sound whenever the key reminder switch, the driver's and front passenger's door lock actuator switches are operated?

Normal conditions are displayed for all the items: Replace the ETACS-ECU. The forgotten key prevention function should work normally.
Scan tool MB991958 does not sound when the key reminder switch is operated: Refer to Inspection Procedure P-1 "ETACS-ECU does not receive a signal from the key reminder switch."
Scan tool MB991958 does not sound when the driver's or the front passenger's door lock actuator switch is operated: Refer to Inspection Procedure P-5 "ETACS-ECU does not receive a signal from the driver's or front passenger's door lock actuator switch."