Inspection Procedure L-3

Dome light: Dome Light Dimming Function does not Work Normally.

Interior Light Automatic Shut-down Function Circuit:

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 dome light dimming function according to the input signals from the following switches:
- Ignition switch (IG1): OFF
- Key reminder switch: ON
- Door switches: OFF
- Driver's door lock actuator switch: LOCK or UNLOCK

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
- Malfunction of the key reminder switch
- Malfunction of the door switches
- Malfunction of the driver's door lock actuator switch
- 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. Check the dome light.
If a door is opened while the dome light switch is at "door-linked" position, the dome light should illuminate.

Q: Does the dome light illuminate normally?

YES: Go to Step 2.

NO: Refer to Inspection Procedure L-1 "Dome light does not illuminate or go out normally."







STEP 2. 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 3.

NO: Refer to Inspection Procedure A-3 "Communication with ETACS-ECU is impossible."










STEP 3. Check the input signal by using service data of the SWS monitor.
Turn the ignition switch to the "OFF" position before checking input signals from the ignition switch (IG1).
Select "ETACS ECU" (DATALIST), and check that normal conditions are displayed on the items described in the table.

Q: Does the scan tool display "IG SW (IG1)" as normal condition?

YES: Go to Step 4.

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







STEP 4. Check the input signal (by using the Pulse check).
Check the input signals from the following switches:
- key reminder switch
- all door switch

If the switches which are applicable for the input signal check, are operated, check if scan tool MB991502 sounds or not.

Q: When the key reminder switch and each door switch are operated, does scan tool MB991502 sound in each case?

YES: Replace the ETACS-ECU. Check that the dome light dimming function works normally.

NO:
- Scan tool MB991502 does not sound when the key reminder switch is operated: Refer to Inspection Procedure O-1 "ETACS-ECU does not receive a signal from the key reminder switch."
- Scan tool MB991502 does not sound whenever each door switch is operated: Refer to Inspection Procedure O-4 "ETACS-ECU does not receive a signal from all the door switches."