Inspection Procedure J-7

J-7 Headlight, taillight: Headlight dimmer switch automatic resetting function does not work normally.






CIRCUIT OPERATION
When the passing switch is on or the front-ECU is illuminating the headlights (high-beam), the ETACS-ECU illuminates the high-beam indicator light.

TECHNICAL DESCRIPTION (COMMENT)
If the headlights (high-beam and passing) operate normally, the combination meter (high-beam indicator light bulb or printed-circuit board), the front-ECU or the ETACS-ECU is suspected to be defective.

TROUBLESHOOTING HINTS
- The combination meter (high-beam indicator light bulb or printed-circuit board) may be defective
- The front-ECU may be defective
- The ETACS-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 Tool:
- MB991223: Test Harness Set

STEP 1. Verify the headlights (high-beam and passing) operation.

Q: Do the headlights (high-beam and passing) illuminate normally?

YES : Go to Step 2.

NO : Solve the problem first. Inspection Procedure J-6

STEP 2. Check the high-beam indicator light circuit at the ETACS-ECU connector C-318.

1. Disconnect the ETACS-ECU connector C-318 and measure at the wiring harness side.






2. Connect terminal 72 to the ground. Q: Does the high-beam indicator light illuminate?

YES : Go to Step 10.

NO : Go to Step 3.






STEP 3. Check the high-beam indicator light bulb.

Q: Is the high-beam indicator light bulb in good condition?

YES : Go to Step 4.

NO : Replace it. The high-beam indicator light should work normally.






STEP 4. Check the combination meter (printed-circuit board).

1. Remove the combination meter.
2. Remove the high-beam indicator light bulb. Then measure the resistance between the bulb terminals.






3. Install the bulb to the combination meter, and then measure the resistance between connector C-102 terminal 21 and 22. The resistance reading at this time should be muck the same as the resistance measured at Step (2).

Q: Are the two resistance values extremely different each other?

YES : Repair or replace the combination meter (printed circuit board). The high-beam indicator light should work normally.

NO (much the same): Go to Step 5.

STEP 5. Check the battery power supply circuit to the combination meter. Test at combination meter connector C-102.






1. Disconnect the combination meter connector C-102 and measure the voltage available at the wiring harness side of the connector.






2. Measure the voltage between terminal 21 and ground.
- The voltage should equal approximately 12 volts (battery positive voltage).

Q: Is the measured voltage approximately 12 volts (battery positive voltage)?

YES : Go to Step 8.

NO : Go to Step 6.

STEP 6. Check the combination meter connector C-102 for loose, corroded or damaged terminals, or terminals pushed back in the connector.






Q: Is combination meter connection C-102 in good condition?

YES : go to step 7.

NO : Repair or replace the damaged components). Refer to Harness Connector Inspection. The high-beam indicator light should work normally.

STEP 7. Check the wiring harness between combination meter connector C-102 and battery.











NOTE: After checking joint connector C-141 and intermediate connector C-209, check the wires. If joint connector C-141 or intermediate connector C-209 are damaged, repair or replace them Refer to Harness Connector Inspection.

Q: Are the harness wires between combination meter connector C-102 and battery in good condition?

YES : No action is necessary and testing is complete.

NO : Repair or replace them. The high-beam indicator light should work normally.











STEP 8. the combination meter connector C-102 and ETACS-ECU connector C-318 for loose, corroded or damaged terminals, or terminals pushed back in the connector.

Q: Are combination meter connector C-102 and ETACS-ECU connector C-318 in good condition?

YES : Go to Step 9.

NO : Repair or replace the damaged component(s). Refer to Harness Connector Inspection. The high-beam indicator light should work normally.











STEP 9. Check the wiring harness between combination meter connector C-102 and ETACS-ECU connector C-318.

Q: Are the combination meter connector C-102 and ETACS-ECU connector C-318 in good condition?

YES : No action is necessary and testing is complete.
NO : Repair it. The high=beam indicator light should work normally.

STEP 10. Replacement of ECU.
1. Replace the ETACS-ECU.
2. The high-beam indicator light should work normally.

Q: Is the high-beam indicator light working normally?

YES : No action is necessary and testing is complete.

NO : Replace the front-ECU. The high-beam indicator light should work normally.