Inspection Procedure L-2

Interior light: Interior light does not work normally.

Interior Lights Drive Circuit:

CIRCUIT OPERATION
Interior lights (dome light and rear personal lights) are turned on and off by ETACS-ECU. Interior lights are controlled by ETACS-ECU, only when switch position is set to the position "door controlled operation position."

TECHNICAL DESCRIPTION (COMMENT)
The ETACS-ECU dims the interior lights according to the input signals from the following switches:
- Ignition switch (IG1)
- Key reminder switch
- Door switches
- Driver's door lock actuator switch
- Trunk lid latch switch

If the interior light does not be dimmed normally, the relevant input signal circuit or the ETACS-ECU may be defective.

NOTE: If only one the interior lights does not illuminate, the relevant bulb may be burned out or the harness wire between the defective light and the ETACS-ECU may be defective. In this case, check the relevant circuit by referring to Interior Lights.

TROUBLESHOOTING HINTS
- Malfunction of the ETACS-ECU
- Damaged harness wires or connectors

DIAGNOSIS

Required Special Tools:
- MB991223: Test Harness Set
- MB991502: Scan Tool (MUT-II)
- MB991529: Diagnostic Trouble Code Check Harness

STEP 1. Check the ETACS-ECU power supply circuit.
Do all of the following functions work when the ignition switch is turned to the "LOCK" (OFF) position?
- Ignition key reminder tone alarm function
- Light reminder tone alarm function
- Central door locking system
- Hazard warning light
- Theft-alarm system

Q: Do any of the functions work?

YES: Go to Step 2 or 3 .
NO: Check the ETACS-ECU battery circuit. Refer to Inspection Procedure P-1.

STEP 2. Check the input signal (by using scan tool MB991502).
Check the input signals from the following switches:
- Ignition switch (IG1)
- key reminder switch
- Door switches
- Driver's door lock actuator switch
- Trunk lid latch switch

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.

1. Connect scan tool MB991502 to the data link connector.
2. Check that the tone alarm of scan tool MB991502 sounds when the input signal enters.

Q: Does the tone alarm of scan tool MB991502 sound when the input signal enters?

YES: Go to Step 4.
NO: Check the relevant input signal circuit.

STEP 3. Check the input signal (by using a voltmeter).
Check the input signals from the following switches:
- Ignition switch (IG1)
- Key reminder switch
- Driver's and passenger's door switch
- Driver's door lock actuator switch

1. Use special tool MB991529 to connect a voltmeter between ground terminal 4 or 5 and ETACS-ECU terminal 9 of the data link connector.
2. Check that the voltmeter indicator deflects once when the input signal enters.

Q: Does the voltmeter indicator deflect?

YES: Go to Step 4.
NO: Check the relevant input signal circuit.

STEP 4. Check the ETACS-ECU connector C-311 and junction block connectors C-306 and C-307 for damage.

Q: Are ETACS-ECU connector C-311 and junction block connectors C-306 and C-307 in good condition?

YES: Go to Step 5.
NO: Repair or replace them. Refer to Harness Connector Inspection. The interior lights should illuminate normally.

STEP 5. Check the harness wire between ETACS-ECU connector C-311 and junction block connectors C-306 and C-307.

Q: Is the harness wire between ETACS-ECU connector C-311 and junction block connectors C-306 and C-307 in good condition?

YES: Replace the ETACS-ECU. The interior lights should illuminate normally.
NO: Repair it. The interior lights should illuminate normally.