INSPECTION PROCEDURE J-4: Headlight, Taillight: Headlights do not illuminate when the passing switch is operated.: Diagnosis
Required Special Tools:
- MB991223: Test Harness Set
- MB991502: Scan Tool (MUT-II)
- MB991529: Diagnostic Trouble Code Check Harness
- STEP 1. Verify the headlight (low-beam and high-beam) operation.
Q: Do the headlights (low-beam and high-beam) illuminate normally?
YES : Go to Step 2 < when using scan tool MB991502 > or 3 < when using a voltmeter >.
NO: Solve the problem first. Refer to SYMPTOM CHART .
- STEP 2. Check the input signal (by using scan tool MB991502).
Check the input signal from the passing 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.- Connect scan tool MB991502 to the data link connector.
- 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 : Replace the front-ECU. The passing switch should work normally.
NO: Scan tool MB991502 does not sound when the passing switch is turned from "OFF" to "ON": Refer to INSPECTION PROCEDURE O-14 "THE PASSING SWITCH SIGNAL IS NOT SENT TO THE ETACS-ECU ."
- STEP 3. Check the input signal (by using a voltmeter).
Check the input signal from the passing switch.
- Use special tool MB991529 to connect a voltmeter between ground terminal 4 or 5 and ETACS-ECU terminal 9 of the data link connector.
- Check that the voltmeter indicator deflects once when the input signal enters.
Q: Does the voltmeter indicator deflect?
YES : Replace the front-ECU. The passing switch should work normally.
NO: The voltmeter needle does not fluctuate when the passing switch is turned from "OFF" to "ON": Refer to INSPECTION PROCEDURE O-14 "THE PASSING SWITCH SIGNAL IS NOT SENT TO THE ETACS-ECU ."