Inspection Procedure M-3

Interior Light: The front dome light and the rear dome light dimming 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."

Interior Light Automatic Shut-down Function Circuit:

CIRCUIT OPERATION
The ETACS-ECU operates the dome light dimming function according to the following switches:
- Ignition switch (IG1)
- Key reminder switch
- Front door switches
- Driver's door lock actuator switch

TECHNICAL DESCRIPTION (COMMENT)
Is the dome lights do not dim normally, the input circuits from the switches described in "CIRCUIT OPERATION" or the ETACS-ECU may be defective.

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
- " MB992006: Extra Fine Probe
- MB991958: Scan Tool (M.U.T.-III Sub Assembly)
- MB991824: V.C.I.
- MB991827: M.U.T.-III USB Cable
- MB991911: M.U.T.-III Main Harness B
- MB991813: SWS monitor kit
- MB991806: SWS monitor cartridge
- MB991812: SWS monitor harness (for column-ECU)
- MB991922: Probe harness

STEP 1. Verify the front dome light and the rear dome light operation.
If the front dome light switch and the rear dome light switch are moved to the "door interlock position", the front dome light and the rear dome light should illuminate when either door is opened.

Q: Do the front dome light and the rear dome light illuminate normally?

YES : Go to Step 2.

NO : Refer to Inspection Procedure M-1 "The front dome light, the rear dome light and the luggage compartment light do not illuminate or go out normally."

NO : Refer to Inspection Procedure M-2 "The front dome light, the rear dome light or the luggage compartment light do not illuminates or goes out normally."

STEP 2. 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 ."
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" menu for the "ETACS ECU" menu.

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

YES: Go to Step 3.

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

STEP 3. Check the input signal by using "DATA LIST" menu of the SWS monitor.
Check the input signals from the following switches:
- Ignition switch: ON or START
- Driver's door: open

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: Does the scan tool MB991958 display the items "IG SW (IG1)" and "FRONT DOOR SW" as normal condition?

YES : Go to Step 4.

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

NO : Refer to Inspection Procedure N-5 "The ETACS-ECU does not receive any signal from the front door switches."

STEP 4. Check the input signal (by using the Pulse check mode of the monitor).
Check the following switches and input signals:
- Key reminder switch
- All door switches
- Interior light loaded signal

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. Check if scan tool MB991958 sounds.

Q: When the key reminder switch, each door switch and the interior light are operated, does scan tool MB991958 sound in each case?

YES : Replace the ETACS-ECU. Verify that the dome light illuminates normally.

NO key is removed and reinserted> : Refer to Inspection Procedure O-1 "The ETACS-ECU does not receive any signal from the key reminder switch."

NO : Refer to Inspection Procedure O-4 "The ETACS-ECU does not receive any signal from all the door switches."

NO : Refer to Inspection Procedure O-10 "The ETACS-ECU does not receive any interior light loaded signal."