1. Taillights Do Not Light Up, Bulb is Ok
CIRCUIT OPERATION
- When the lighting switch is turned to the first position, the ETACS-ECU sends a driving signal to the FRONT-ECU which turns on the taillight relay, causing the taillights to light up.
TECHNICAL DESCRIPTION (COMMENT)
The ETACS-ECU determines whether the light switch is at the first position, and monitors the ETACS-ECU and FRONT-ECU.
TROUBLESHOOTING HINTS
- Malfunction of the column switch
- Malfunction of the FRONT-ECU
- Malfunction of the ETACS-ECU
- Malfunction of the taillight relay
- 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 or disconnecting the scan tool.
STEP 1. Check the input signal from the lighting switch.
- 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 first position.
If the tone alarm of the scan tool does not sound, the input signal from the lighting switch (first 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 first position, the 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 g of the data link connector.
2. If a voltmeter indicator deflects once when the lighting switch first position, the ETACS-ECU input signal for that taillight switch circuit is normal.
If the input signal of the lighting switch (first 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 first position, the scan tool is normal. Go to Step 3.
STEP 2. Check diagnostic trouble codes using scan tool MB991502.
If no DTC is displayed, go to Step 3.
If DTC 11 is displayed, go to Step 18.
If DTC 12 is displayed, go to Step 14.
If DTC 13 is displayed, go to Step 10.
If DTC 21 is displayed, go to Step 25.
STEP 3. Check taillight relay continuity.
1. Remove the taillight relay.
2. Check continuity of the taillight relay.
If the taillight relay is in good condition, go to Step 4. It the taillight relay is faulty, replace it. Check that the malfunction is eliminated.
STEP 4. Check taillight relay connector A-05X and FRONT-ECU connector A-09X for damage.
If harness connectors A-05X and A-09X are damaged, repair them. Refer to Harness Connector Inspection.
If connectors A-05X and A-09X are in good condition, go to Step 5.
STEP 5. Check the harness wires between FRONT-ECU connector A-09X and taillight relay connector A-05X.
If the harness wires between FRONT-ECU connector A-09X and taillight relay A-05X 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 taillight relay connector A-05X and the battery.
If the harness wires between taillight relay connector A-05X 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 taillight relay connector A-05X and dedicated fuses number 8 and 9.
If the harness wires between taillight relay connector A-05X and dedicated fuses number 8 and 9 are damaged, replace them. Check that the malfunction is eliminated.
It the harness wires are in good condition, go to Step 8.
STEP 8. Check FRONT-ECU connector A-09X and ETACS-ECU connector C-82 for damage.
If harness connectors A-09X and C-82 are damaged, repair them. Refer to Harness Connector Inspection.
If the harness connectors A-09X and C-82 are in good condition, go to Step 9.
If the harness connectors A-09X and C-82 are damaged, repair or replace them.
STEP 9. Check the harness wires between FRONT-ECU connector A-O9X and ETACS-ECU connector C-82.
If the harness wires between FRONT-ECU connector A-09X or ETACS-ECU connector C-82 is damaged, replace it. Check that the malfunction is eliminated.
If the harness wires are in good condition, go to Step 10.
NOTE: After checking intermediate connector C-66, check the wires. If intermediate connector C~6 is damaged, repair or replace it. Refer to Harness Connector Inspection.
Step 10. 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.
- Voltage should be approximately 12 volts (battery positive voltage).
If approximately 12 volts, go to Step 13.
If not approximately 12 volts, go to Step 11.
STEP 11. Check FRONT-ECU connector A-09X and ignition switch connector (IG2) for damage.
If FRONT-ECU connector A-09X is damaged, repair it. Refer to Harness Connector Inspection.
Go to Step 12.
STEP 12. Check harness wires between FRONT-ECU connector A-09X and the ignition switch (1G2).
If the harness wires between FRONT-ECU connector A-09X and the ignition switch (IG2) are damaged, repair them.
If the harness wires are in good condition, go to Step 13.
NOTE: After checking intermediate connector C-66 and junction block connectors C-73 and C-78, check the wires. If any of intermediate connector C-66 and junction block connectors C-73 and C-78 is/are damaged, repair or replace. Refer to, Connector Inspection.
STEP 13. Check the FRONT-ECU connector A-09X ground circuit.
If the harness wires between FRONT-ECU connector A-09X and body ground are damaged, repair them.
If the harness wires are in good condition, replace the FRONT-ECU and check that the malfunction is eliminated.
STEP 14. 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.
- 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 column switch connector C-60 and ignition switch (IG1) connector for damage.
If column switch connector C-60 is damaged, repair it. Refer to Connector Harness Inspection.
If column switch connector C-60 is in good condition, go to Step 16.
STEP 16. 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 the ignition switch (IG1) are damaged, repair them.
If the harness wires are in good condition, go to Step 17.
NOTE: After checking junction block connector C-73, check the wire. If junction block connector C-73 is damaged, repair or replace it. Refer to Connector Inspection.
STEP 17. 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 condition, replace the column switch and check that the malfunction is eliminated.
NOTE: After checking intermediate connector C-84, check the wire. If intermediate connector C-84 is damaged, repair or replace it. Refer to Connector Inspection.
STEP 18. Check the ETACS-ECU power supply circuit.
1. Disconnect ETACS-ECU connector 0-86 and measure at the harness side.
2. Measure voltage between terminal 2 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 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 20.
STEP 20. Check the harness wires between the ETACS-ECU and battery.
If the harness wires between the ETACS-ECU and battery are damaged, repair them.
If the harness wires are in good condition, go to Step 21.
NOTE: After inspecting intermediate connector C-86 and junction block connector C-84, inspect the wire. If intermediate connector C-86 or junction block connector C-84 is damaged, repair it. Refer to Connector Inspection.
STEP 21. Check the ETACS-ECU power supply circuit.
1. Disconnect ETACS-ECU connector C-86 and measure at the harness side.
2. Turn the ignition key on.
3. Measure voltage between terminal number 11 and the ground.
- The voltage should be approximately 12 volts (battery positive voltage).
If approximately 12 volts, go to Step 24. If not approximately 12 volts, go to Step 22.
STEP 22. 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 23.
STEP 23. Check the harness wires between ETACS-ECU connector C-86 and ignition switch (IG1).
If the harness wires between ETACS-ECU and ignition switch (IG1) are damaged, repair them.
If the harness wires are in good condition, go to Step 24.
NOTE: After inspecting junction block C-73, inspect the wire. If junction block connector C-73 is damaged, repair or replace it. Refer to Connector Inspection.
STEP 24. Check ETACS-ECU connector C-86 ground circuit.
It the harness wires between ETACS-ECU connector C-86 and body ground are damaged, repair them.
If the harness wires are in good condition, replace the ETACS-ECU and check that the malfunction is eliminated.
STEP 25. 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 are damaged, repair them. Refer to Connector Harness Inspection.
If the connectors are in good condition, go to Step 26.
STEP 26. Check the harness wires between column switch connector C-82 and ETACS-ECU connector C-82.
It 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 27.
STEP 27. Check column switch connector C-82 and FRONT-ECU connector A-09X for damage.
If column switch connector C-60 or FRONT-ECU connector A-09X are damaged, repair them. Refer to Connector Harness Inspection.
If the connectors are in good condition, go to Step 28.
STEP 28. 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 them.
If the harness wires are in good condition, go to Step 29.
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 29. Check symptoms.
Confirm that the taillights illuminate properly.