Inspection Procedure J-4
INSPECTION PROCEDURE J-4: Headlight, Taillight: Headlights do not illuminate when the passing switch is operated.
TECHNICAL DESCRIPTION (COMMENT)
If the column switch or the front-ECU is suspected to be defective.
TROUBLESHOOTING HINTS
- The column switch (turn-signal light and lighting switch) may be defective
- The front-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 headlight (low-beam and high-beam) operation.
Q: Do the headlights (low-beam and high-beam) illuminate normally?
YES : Go to Step 2
NO : Solve the problem first. See J2 Inspection Procedure J-2 and J3 Inspection Procedure J-3 symptom charts.
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.
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 : 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." Inspection Procedure O-14
STEP 3. Check the input signal (by using a voltmeter).
Check the input signal from the passing 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 : 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." Inspection Procedure O-14