Inspection Procedure M-2

TECHNICAL DESCRIPTION (COMMENT)
The ETACS-ECU dims the dome light according to the input signals from the following switches:
- Ignition switch (IG1)
- Key reminder switch
- Driver's or passenger's door switch
- Driver's door lock actuator switch

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

TROUBLESHOOTING HINTS
- Malfunction of the key reminder switch
- Malfunction of the driver's or passenger's door switch
- 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)
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 "LOCK" (OFF) position?
- Ignition key reminder tone alarm function
- Light reminder tone alarm function
- Central door locking system
- Hazard warning light
- Theft-alarm system

If no functions work normally, check the ETACS-ECU battery circuit. Refer to Inspection Procedure P-1.
P - Charts

If any of the functions work, go to Step 2.

STEP 2. Check the input signal.
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

CAUTION: To prevent damage to scan tool MB991502, always turn the ignition switch to "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.

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.
If one of the input signal checks above shows a defect, check the relevant input signal circuit.
If none of the input signal checks shows a defect, replace the ETACS-ECU.
The dome light dimming function should work normally.