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-101 terminal 4 and 5. The resistance reading at this time should be much 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-101.






1. Disconnect the combination meter connector C-101 and measure the voltage available at the wiring harness side of the connector.






2. Measure the voltage between terminal 4 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-101 for loose, corroded or damaged terminals, or terminals pushed back in the connector.






Q: Is combination meter connection C-101 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-101 (terminal 4) and battery.

NOTE: Also check junction block connector C-308 and c-313 and intermediate connector C-209 for loose, corroded, or damaged terminals, or terminals pushed back in the connector. If junction block connector C-308 or C-313 or intermediate connector C-209 is damaged, repair or replace the damaged component(s).













Q: Are the wiring harness between combination meter connector C-101 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. Check the combination meter connector C-101 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-101 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-101 (terminal 5) and ETACS-ECU connector C-318 (terminal 72).

Q: Is the wiring harness between combination meter connector C-101 (terminal 5) and ETACS-ECU connector C-318 (terminal 72) in good condition?

YES : No action is necessary and testing is complete.

NO : The wiring harness may be damaged or the connector(s) may have loose, corroded or damaged terminals, or terminals pushed back in the connector. Repair the wiring harness as necessary. 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.