7. No Low Beam With Switch In Second Position

CIRCUIT OPERATION
- If the lighting switch is turned to the second position, the ETACS-ECU sends a 'low beam on' signal to the FRONT-ECU through the SWS line.
- The FRONT-ECU turns on the low-beam side headlight relay, causing the low-beam headlights to light up.

TECHNICAL DESCRIPTION (COMMENT)
The ETACS-ECU determines whether the lighting switch is at second position, and monitors the column switch, ETACS-ECU and 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 Tool:
MB991502: Scan Tool (MUT-II)

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 a diagnostic trouble code. Connect scan tool MB991502 to the data link connector, then check the diagnostic trouble code.
It 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 2.




STEP 2. Check column switch C-60 and ETACS-ECU connector C-60 and ETACS-ECU connector C-82 for damage.
If column switch connector C-60 and ETACS-ECU connector C-82 are damaged, repair them. Refer to Harness Connector Inspection.
If the connectors are in good condition, go to Step 3.




STEP 3. Check the harness wires between column switch connector C-80 and ETACS-ECU connector C-82.
If the harness wires between column switch connector C-60 and ETACS-ECU connector C-82 ETACS-ECU are damaged, repair them.
If the harness wires are in good condition, go to Step 4.







STEP 4. Check the harness wires between column switch C-60 and FRONT-ECU connector A-09X for damage.
It the harness wires between column switch C-60 and FRONT-ECU connector A-09X are damaged, repair them. Refer to Harness Connector Inspection.
If the harness wires are in good condition, go to Step 5.




STEP 5. Check the harness wires between column switch C-60 and FRONT-ECU connector C42.
If the harness wires between column switch C-60 and FRONT-ECU are damaged, repair them.
If the harness wires are in good condition, go to Step 6.

STEP 6. Check symptoms.
Confirm that the automatic reset function for headlight dimmer switch is normal. The headlights should always come on in low beam.