Inspection Procedure M-2

INSPECTION PROCEDURE M-2: Interior light: Interior light dimming function does not work normally.

Interior Lights Drive Circuit:

TECHNICAL DESCRIPTION (COMMENT)
The ETACS-ECU operates the interior light dimming function according to the following switch signals.
- Ignition switch (IG1)
- Key reminder switch
- driver's or passenger's door switches
- Driver's door lock actuator switch If the interior light does not dim normally, the relevant input signal circuit or the ETACS-ECU may be defective.

TROUBLESHOOTING HINTS
- The key reminder switch may be defective
- The driver's or passenger's 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: Test Harness Set
- MB991502: Scan Tool (MUT-II)
- MB991529: Diagnostic Trouble Code Check Harness

STEP 1. Verify the interior light.

If the dome light switch and the rear personal light switch are moved to the "door interlock position," the interior light should illuminate when either door is opened.

Q: Does the interior light illuminate normally?

YES: Go to Step 2.
NO: Solve the problem first. Refer to Inspection Procedure M-1. Inspection Procedure M-1

STEP 2. Verify the ETACS-ECU power supply circuit.

Check that the hazard warning light illuminate when the ignition switch is in the "LOCK" (OFF) position.

Q: Does the hazard warning light illuminate?

YES: Go to Step 3 or 4 .
NO: Check the ETACS-ECU battery circuit. Refer to Inspection Procedure P-1. Inspection Procedure P-1

STEP 3. Check the input signal (by using scan tool MB991502).

Check the input signals from the following switches:
- Ignition switch (IG1)
- Key reminder switch
- driver's and passenger's door switches
- Driver's door lock actuator 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 5.
NO:
- Scan tool MB991502 does not sound when the ignition switch is turned from "ACC" to "ON": Refer to Inspection Procedure O-2 "The ignition switch (IG1) signal is not sent to the ETACS-ECU." Inspection Procedure O-2
- Scan tool MB991502 does not sound when the ignition key is inserted and then removed: Refer to Inspection Procedure O-3 "The key reminder switch signal is not sent to the ETACS-ECU." Inspection Procedure O-3
- Scan tool MB991502 does not sound when the driver's door is opened: Refer to Inspection Procedure O-8 "The driver's or passenger's door switch signal is not sent to the ETACS-ECU." Inspection Procedure O-8
- Scan tool MB991502 does not sound when the driver's door is unlocked: Refer to Inspection Procedure O-10 "The driver's or passenger's door lock actuator switch signal is not sent to the ETACS-ECU." Inspection Procedure O-10

STEP 4. 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 5.
NO:
- The voltmeter needle does not fluctuate when the ignition switch is turned from "ACC" to "ON": Refer to Inspection Procedure O-2 "The ignition switch (IG1) signal is not sent to the ETACS-ECU." Inspection Procedure O-2
- The voltmeter needle does not fluctuate when the ignition key is inserted and then removed: Refer to Inspection Procedure O-3 "The key reminder switch signal is not sent to the ETACS-ECU." Inspection Procedure O-3
- The voltmeter needle does not fluctuate when the driver's door is opened: Refer to Inspection Procedure O-8 "The driver's or passenger's door switch signal is not sent to the ETACS-ECU." Inspection Procedure O-8
- The voltmeter needle does not fluctuate when the driver's door is unlocked: Refer to Inspection Procedure O-10 "The driver's or passenger's door lock actuator switch signal is not sent to the ETACS-ECU." Inspection Procedure O-10

STEP 5. Confirm which one of the interior lights do not fade out.

If the dome light is integrated with the inside rear view mirror, the mirror assembly built-in circuit makes the dome light fade out.

Q: Is the dome light integrated in the inside rear view mirror?

YES: Go to Step 6.
NO: Replace the ETACS-ECU. Check that the interior light dim normally.

STEP 6. Check by replacing the inside rear view mirror.

1. Replace the inside rear view mirror.
2. Check if the dome light fades out.

Q: Does the dome light fade out?

YES: No action is necessary and testing is complete.
NO: Replace the ETACS-ECU. Check that the interior light dim normally.