8. Headlights Do Not Change With Dimmer Switch Operation
The headlights cannot be dimmed or returned to high beam when the dimmer switch is operated.Dimmer Switch Circuit
TECHNICAL DESCRIPTION (COMMENT)
The dimmer switch sends an incorrect signal to the FRONT-ECU.
TROUBLESHOOTING HINTS
- Malfunction of the column switch
- Malfunction of the FRONT-ECU
- Malfunction of the ETACS-ECU
- Damaged harness wires or connectors
DIAGNOSIS
Required Special Tools:
MB991502: Scan Tool (MUT-II)
MB991529: Diagnostic Trouble Code Check Harness
CAUTION: To prevent damage to scan tool MB991502, make sure that the ignition switch is "OFF" before connecting and disconnecting the scan tool.
STEP 1. Check the input signal from the dimmer switch, using either the scan tool or a voltmeter
- Using scan tool MB991502
1. Connect scan tool MB991502.
2. Check that the tone alarm of the scan tool sounds when the dimmer switch is at LO and HI positions.
If the tone alarm of the scan tool does not sound, the input signal from the dimmer switch LO and HI positions is not normal. Go to Step 2.
If the tone alarm of the scan tool sounds when the dimmer switch is at LO and HI positions, scan tool is normal. Go to Step 3.
- Using a voltmeter
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. If a voltmeter indicator deflects once when the dimmer switch is set to LO and HI positions, the ETACS-ECU input signal for that taillight switch circuit is normal.
If the input signal of the dimmer switch at LO and HIGH positions is not normal, go to Step 2.
If the tone alarm of the scan tool sounds when the dimmer switch is LO and HIGH position, the scan tool is normal, go to Step 3.
CAUTION: To prevent damage to scan tool MB991502, make sure that the ignition switch is "OFF" before connecting and disconnecting the scan tool.
STEP 2. Check a diagnostic trouble code.
Connect scan tool MB991502 to the data link connector, then check a diagnostic trouble code.
If diagnostic trouble code 11 is displayed, replace the ETACS-ECU, and check that the malfunction is eliminated.
If diagnostic trouble code 12 is displayed, replace the column switch, and check that the malfunction is eliminated.
If diagnostic trouble code 13 is displayed, replace the FRONT-ECU, and check that the malfunction is eliminated. If diagnostic trouble code 21 is displayed, go to Step 3.
STEP 3. Check column switch connector C-60 and ETACS-ECU connector C-82 for damage.
If column switch connector C-60 or ETACS-ECU connector C-82 is damaged, repair it.
It the connectors are in good condition, go to Step 4.
STEP 4. Check the harness wires between column switch connector C-60 and ETACS-ECU connector C-82.
If the harness wires between column switch connector C-60 and ETACS-ECU connector C-82 are damaged, repair them.
If the harness connectors are in good condition, go to Step 5.
STEP 5. Check column switch C-60 connector and FRONT-ECU connector A-09X for damage.
If column switch connector C-60 or FRONT-ECU connector A-09X is damaged, repair it. Refer to Harness Connector Inspection.
If the connectors are in good condition, go to Step 6.
STEP 6. Check column switch connector C-60 and FRONT-ECU connector A-09X for damage.
If column switch connector C-60 and FRONT-ECU connector A-09X are damaged, repair them. Refer to Harness Connector Inspection.
If the connectors are in good condition, go to Step 7.
STEP 7. Check the harness wires between column switch C-60 and FRONT-ECU C-82.
If the harness wires between column switch C-60 and ETACS-ECU C-82 are damaged, repair them. Refer to Harness Connector Inspection.
If the harness wires are in good condition, go to Step 8.
STEP 8. Check symptoms
Confirm that the automatic reset function for headlight dimmer switch operates normally.