Inspection Procedure J-3
INSPECTION PROCEDURE J-3: Headlight, Taillight: Headlights (high-beam) do not illuminate.
CIRCUIT OPERATION
If the column switch sends the dimmer switch ON signal to the front-ECU, the front-ECU switches the headlights from low-beam to high-beam or vice versa.
TECHNICAL DESCRIPTION (COMMENT)
The column switch or the front-ECU may be defective.
NOTE: If only one of the headlights does not illuminate, the light bulb may be burned out or the wiring harness between the light and the front-ECU may be defective. In this case, check the circuit by referring to Headlight.
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. Verity the headlight (low-beam) operation.
Q: Do the headlights (low-beam) illuminate normally?
YES : Go to Step 2
NO : Solve the problem first. Refer to Inspection Procedure J-2. Inspection Procedure J-2
STEP 2. Check the input signal (by using scan tool MB991502).
Check the input signal from the dimmer 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. Check that the tail lights illuminate normally.
NO : Scan tool MB991502 does not sound when the dimmer switch is turned from "OFF" to "ON": Refer to Inspection Procedure O-14 "The dimmer 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 dimmer 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. Check that the tail lights illuminate normally.
NO : Scan tool MB991502 does not sound when the dimmer switch is turned from "OFF" to "ON": Refer to Inspection Procedure O-14 "The dimmer switch signal is not sent to the ETACS-ECU." Inspection Procedure O-14