Inspection Procedure M-3
Interior light: Front dome light and rear dome light dimming function does not work normally.Interior Light Automatic Shut-down Function Circuit:
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." How To Use SWS Monitor
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
- The key reminder switch may be defective
- The door switches may be defective
- The driver'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: Vehicle Communication Interface (V.C.I.)
- MB991827: MUT-III USB Cable
- MB991910: MUT-III Main Harness A
- MB991813: SWS monitor kit
- MB991806: SWS Monitor Cartridge
- MB991812: SWS Monitor Harness (For Column-ECU)
- MB991822: Probe Harness
- MB991854: SWS Monitor Harness (For 13-pin)
STEP 1. Verify the front dome light and the rear dome light.
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
NO
NO
STEP 2. 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.
1. Connect scan tool MB991958 to the data link connector (16-pin).
2. Connect SWS monitor harness MB991854 to the data link connector (13-pin).
3. Turn the ignition switch to the "LOCK" (OFF) position.
4. Operate the scan tool MB991958 according to the procedure below to display "ECU COMM CHECK."
a. Select "SYSTEM SELECT."
b. Select "SWS."
c. Select "SWS MONITOR."
d. Select "ECU COMM CHK".
5. 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 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 switches in the following conditions:
- Turn the ignition switch to the "ON" or "START" position.
- Open the driver's door. (The front door switch (LH) is turned to the ON position.)
1. Operate the 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: Are normal conditions displayed on the "IG SW (IG1)" and "FRONT DOOR SW"?
YES
NO
NO
STEP 4. Check the input signal (by using the pulse checking mode of the monitor).
Check the following switches and input signals:
- Key reminder switch
- All door switches
- Interior light loaded signal
1. Operate the scan tool MB991958 according to the procedure below to display "PULSE CHECK."
a. Select "SYSTEM SELECT."
b. Select "SWS."
c. Select "PULSE CHECK."
2. Check if scan tool MB991958 sounds or not.
Q: When the key reminder switch, each door switch and the interior light are operated, does scan tool MB991958 sound in each case?
YES
NO
NO
NO