6. Headlights Do Not Light Up, Bulbs Are OK
CIRCUIT OPERATION
- When the lighting switch is turned to the second position, the ETACS-ECU sends a driving signal to the FRONT-ECU through the SWS.
- When the column switch sends a 'light on' signal to the FRONT-ECU, the FRONT-ECU turns on the high-beam or low-beam side headlight relay, causing the headlights to light up.
TECHNICAL DESCRIPTION (COMMENT)
The ETACS-ECU determines whether the lighting switch is at the second position, and monitors the ETACS-ECU and FRONT-ECU.
If neither of the headlights lights up, it is suspected that the FRONT-ECU does not energize the headlight relays.
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:
MB991223: Harness Set
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 lighting switch, using either the scan tool or a voltmeter.
- Using scan tool MB991502
1. Connect scan tool MB991502 to the data link connector.
2. Check that the tone alarm of the scan tool sounds when the lighting switch from OFF position to the second position.
If the tone alarm of the scan tool does not sound, the input signal from the lighting switch (the second position) is not normal. Go to Step 2.
The tone alarm of the scan tool sounds when the lighting switch is moved from the OFF position to the second position, the scan tool is normal. Go to Step 3.
- Using a voltmeter
1. Use special tool MB991529 to connect a voltmeter between ground terminals 4 and 5 and ETACS-ECU terminal of the data link connector.
2. If a voltmeter indicator deflects once when the lighting switch is set to the second position, the ETACS-ECU input signal for that taillight switch circuit is normal.
If the input signal from the lighting switch (the second position) is not normal, go to Step 2.
If the tone alarm of the scan tool sounds when the lighting switch is moved from the OFF position to the second position, the scan tool is normal. Go to Step 3.
STEP 2. Check a diagnostic trouble code. Connect scan tool MB991502 to the data link connector, then check a diagnostic trouble code.
If no diagnostic trouble code is displayed, go to Step 3.
If diagnostic trouble code 11 is displayed, go to Step 22.
If diagnostic trouble code 12 is displayed, go to Step 18.
If diagnostic trouble code 13 is displayed, go to Step 14.
If diagnostic trouble code 21 is displayed, go to Step 29.
STEP 3. Check headlight relay (LOW) (HIGH) for continuity.
1. Remove the headlight relays (LOW) and (HIGH).
2. Check headlight relays (LOW) and (HIGH) for continuity.
If the headlight relays (LOW) and (HIGH) are in good condition, go to Step 4.
If the relays are faulty, replace them. Check that the malfunction is eliminated.
STEP 4. Check headlight relay (HIGH) connector A-07X and FRONT-ECU connector A-09X for damage.
If connector A-07X or A-09X is damaged, repair it. Refer to Harness Connector Inspection.
If connectors A-07X and A-09X are in good condition, go to Step 5.
STEP 5. Check the harness wires between FRONT-ECU connector A-09X and headlight relay (HIGH) connector A-07X.
If the harness wires between FRONT-ECU connector A-09X and headlight relay (HIGH) connector A-07X are damaged, repair them.
Check that the malfunction is eliminated.
If the harness wires are in good condition, go to Step 6.
STEP 6. Check the harness wires between headlight relay (HIGH) A-07X and the battery.
If the harness wires between headlight relay (HIGH) A-07X and the battery are damaged, repair them.
Check that the malfunction is eliminated.
If the harness wires are in good condition, go to Step 7.
STEP 7. Check the harness wires between headlight relay (HIGH) connector A-07X and dedicated fuses numbers 6 and 7.
If the harness wires between headlight relay (HIGH) A-07X and dedicated fuses numbers 6 and 7 are damaged, repair them.
Check that the malfunction is eliminated.
If the harness wires are in good condition, go to Step 8.
STEP 8. Check headlight relay (LOW) connector A-08X and FRONT-ECU connector A-09X for damage.
If connectors A-08X or A-09X are damaged, repair them. Refer to Harness Connector Inspection.
If connectors A-08X and A-09X are in good condition, go to Step 9.
STEP 9. Check the harness wires between FRONT-ECU connector A-09X and headlight relay (LOW) connector A-08X.
If the harness wires between FRONT-ECU connector A-09X and headlight relay (LOW) A-08X are damaged, repair them. Check that the malfunction is eliminated.
If the harness wires are in good condition, go to Step 10.
STEP 10. Check the harness wires between headlight relay (LOW) and the battery.
If the harness wires between headlight relay (LOW) connector A-08X and the battery are damaged, repair them.
Check that the malfunction is eliminated.
If the harness wires are in good condition, go to Step 11.
STEP 11. Check the harness wires between headlight relay (LOW) A-08X and dedicated fuse numbers 11 and 12.
If the harness wires between headlight relay (HIGH) connector A-08X and dedicated fuse numbers 11 and 12 are damaged, repair them.
Check that the malfunction is eliminated.
If the harness wires are in good condition, go to Step 12.
STEP 12. Check FRONT-ECU connector A-09X and ETACS-ECU connector C-82 for damage.
If connector A-09X or C-82 is damaged, repair it.
If connectors A-09X and C-82 are in good condition, go to Step 13.
STEP 13. Check the harness wires between FRONT-ECU connector A-09X and ETACS-ECU connector C-82.
If the harness wires between FRONT-ECU connector A-09X and ETACS-ECU connector C-82 are damaged, repair them. Check that the malfunction is eliminated.
If the harness wires are in good condition, go to Step 14.
NOTE: After inspecting intermediate connector C-66, inspect the wire. If intermediate connector C-66 is damaged, repair or replace it. Refer to Harness Connector Inspection.
STEP 14. Check the FRONT-ECU power supply circuit.
1. Disconnect FRONT-ECU connector A-09X and measure at the harness side.
2. Turn the ignition key on.
3. Measure voltage between terminal number 15 and the ground.
- The voltage should be approximately 12 volts (battery positive voltage)
If approximately 12 volts, go to Step 17.
If not approximately 12 volts, go to Step 15.
STEP 15. Check FRONT-ECU connector A-09X and the ignition switch connector for damage.
If FRONT-ECU connector A-09X and the ignition switch connector are damaged, repair them. Refer to Connector Harness Inspection. Go to Step 16.
STEP 16. Check harness wires between FRONT-ECU connector A-09X and ignition switch (IG2).
If the harness wires between FRONT-ECU connector A-09X and ignition switch (1G2) are damaged, repair them.
If the harness wires are in good condition, go to Step 17.
NOTE: After inspecting intermediate connector C-66 and junction block connectors C-73 and C-78, inspect the wire.
If intermediate connector C-66, or junction block connector C-73 or C-78 is damaged, repair or replace it. Refer to Connector Inspection.
STEP 17. Check the FRONT-ECU ground circuit.
If the harness wires between the ETACS-ECU and body ground are damaged, repair them.
If harness wires are in good condition, replace the FRONT-ECU. Check that the malfunction is eliminated.
STEP 18. Check the column switch power supply circuit.
1. Disconnect column switch connector C-60.
2. Measure at the harness side of column switch connector C-60.
3. Measure voltage between terminal number 9 and the ground.
- The voltage should be approximately 12 volts (battery positive voltage)
If approximately 12 volts, go to Step 21.
If not approximately 12 volts, go to Step 19.
STEP 19. Check column switch connector C-60 and the ignition switch (IG1) connector for damage.
If column switch connector C-60 is damaged, replace it.
Refer to Connector Harness Inspection.
If column switch connector C-60 is in good condition, go to Step 20.
STEP 20. Check the harness wires between column switch connector C-60 and ignition switch (IG1).
If the harness wires between column switch connector C-60 and ignition switch (IG1) are damaged, repair them.
If the harness wires are in good condition, go to Step 21.
NOTE: After inspecting junction block connector C-73, inspect the wire. If junction block connector C-73 is damaged, repair or replace it. Refer to Connector Inspection.
STEP 21. Check the column switch ground circuit. If the harness wires between the column switch and body ground are damaged, repair them.
If the harness wires are in good conditions, replace the column switch. Check that the malfunction is eliminated.
NOTE: After inspecting intermediate connector C-84, inspect the wire. If intermediate connector C-84 is damaged, repair or replace it. Refer to Connector Inspection.
Step 22. Check the ETACS-ECU power supply circuit.
1. Disconnect ETACS-ECU connector C-86 and measure at the harness side.
2. Measure voltage between terminal number 2 and the ground.
- The voltage should be approximately 12 volts (battery positive voltage).
If approximately 12 volts, go to Step 25. If not approximately 12 volts, go to Step 23.
STEP 23. Check ETACS-ECU connector C-86 for damage.
If ETACS-ECU connector C-86 is damaged, repair it. Refer to Connector Harness Inspection. Go to Step 24.
STEP 24. Check the harness wires between ETACS-ECU connector C-86 and the battery.
If the harness wires between ETACS-ECU and the battery are damaged, repair them.
If the harness wires are in good condition, go to Step 25.
NOTE: After inspecting intermediate connector C-66 and junction block connector C-84, inspect the wire. If intermediate connector C-66 or junction block connector is damaged, repair or replace it. Refer to Connector Inspection.
Step 25. Check the ETACS-ECU power supply circuit.
1. Disconnect ETACS-ECU connector C-86 and measure on the harness side.
2. Turn the ignition key on.
3. Measure voltage between terminal number 11 and the ground.
- Voltage should be approximately 12 volts (battery positive voltage).
If approximately 12 volts, go to Step 28.
If not approximately 12 volts, go to Step 26.
STEP 26. Check ETACS-ECU connector C-86 for damage.
If ETACS-ECU connector C-86 is damaged, repair it.
Refer to Connector Harness Inspection.
Go to Step 27.
STEP 27. Check the harness wires between ETACS-ECU connector C86 and ignition switch (IG1).
If the harness wires between the ETACS-ECU and ignition switch (IG1) are damaged, repair them.
If the harness wires are in good condition, go to Step 28.
NOTE: After inspecting junction block connector C-73, inspect the wire. If junction block connector C-73 is damaged, repair or replace IL Refer to Connector Inspection.
STEP 28. Check the ETACS-ECU ground circuit.
If the harness wires between ETACS-ECU and body ground are damaged, repair them.
If the harness wires are in good condition, replace the ETACS-ECU. Check that the malfunction is eliminated.
STEP 29. Check column switch 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 Connector Harness Inspection.
If the connectors are in good condition, go to Step 30.
STEP 30. Check the harness wires between column switch connector C-60 and ETACS-ECU connector C82.
If the harness wires between column switch connector C-60 and ETACS-ECU connector C-82 are damaged, repair them.
If the harness wires are in good condition, go to Step 31.
STEP 31. Check column switch connector C40 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 Connector Harness Inspection.
If the connectors are in good condition, go to Step 32.
STEP 32. Check the harness wires between column switch connector C-60 and FRONT-ECU connector A-09X.
If the harness wires between column switch connector C-60
and FRONT-ECU connector A-09X are damaged, repair the.
If the harness wires are in good condition, go to Step 33.
NOTE: After inspecting intermediate connector C-66, inspect the wire. If intermediate connector C-66 is damaged, repair or replace it. Refer to Connector Inspection.
STEP 33. Check symptoms.
Confirm that the headlights are illuminated.