Inspection Procedure 2

Inspection Procedure 2: None of headlights (high-beam) illuminates.

CAUTION:
Whenever the ECU is replaced, ensure that the power supply circuit, the ground circuit and the communication circuit are normal.














TECHNICAL DESCRIPTION (COMMENT)

If none of headlights (high-beam) illuminates, the headlight switch input circuit, headlight relay (HIGH), or ETACS-ECU may have a problem.

TROUBLESHOOTING HINTS

- Malfunction of column switch
- Malfunction of headlight relay (HIGH)
- Malfunction of the ETACS-ECU
- Damaged harness wires and connectors

DIAGNOSIS

Required Special Tools:

- MB992006: Extra fine probe
- MB991223: Harness set
- MB991958: Scan Tool (M.U.T.-III Sub Assembly)
- MB991824: Vehicle Communication Interface (V.C.I.)
- MB991827: M.U.T.-III USB Cable
- MB991910: M.U.T.-III Main Harness A (Vehicles with CAN communication system)

STEP 1. Using scan tool MB991958, read the diagnostic trouble code.





(1)
CAUTION:
To prevent damage to scan tool MB991958, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991958.

Connect scan tool MB991958. Refer to "How to connect scan tool (M.U.T.-III) Reading and Clearing Diagnostic Trouble Codes."
(2)Turn the ignition switch to the "ON" position.
(3)Check whether the ETACS-ECU related DTC is set.
(4)Turn the ignition switch to the "LOCK" (OFF) position.

Q. Is the DTC set?

YES Diagnose the ETACS-ECU. Refer to ETACS, Diagnosis Electronic Time and Alarm Control System (ETACS).

NO Go to Step 2.

STEP 2. Using scan tool MB991958, check data list

Use the ETACS-ECU service data to check the signals related to the operation of headlight function.

- Turn the headlight switch to the ON position.





- Turn the passing switch to the ON position.





Q. Does scan tool MB991958 display the items "Headlight switch" and "Headlight switch (flasher)" as normal condition?

YES (Normal conditions are displayed for all items.) Go to Step 3.
NO (Normal condition is not displayed.) Troubleshoot the ETACS-ECU. Refer to ETACS, Diagnosis Symptom Chart.
STEP 3. Check headlight relay (HIGH) connector A-21X for loose, corroded or damaged terminals, or terminals pushed back in the connector.

Q. Is headlight relay (HIGH) connector A-21X in good condition?

YES Go to Step 4.
NO Repair the damaged parts.
STEP 4. Check of headlight relay (HIGH)

Refer to Testing and Inspection.

Q. Is the headlight relay (HIGH) in good condition?

YES Go to Step 5.
NO Replace the headlight relay (HIGH). Verify that the high-beam headlights illuminate normally.
STEP 5. Check the battery power supply circuit to the headlight relay
(HIGH). Measure the voltage at headlight relay (HIGH) connector A-21X

CAUTION:
The top and bottom of the headlight relay (HIGH) are difficult to identify. Prior to inspection, confirm the triangle mark on the relay box.

(1)Disconnect headlight relay (HIGH) connector A-21X and measure the voltage available at the relay box side of the connector.

(2)Measure the voltage between terminal 2 or 4 and ground.
OK: The voltage should measure approximately 12 volts (battery positive voltage).


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

YES Go to Step 6.
NO Go to Step 8.
STEP 6. Check ETACS-ECU connector C-312 for loose, corroded or damaged terminals, or terminals pushed back in the connector.

Q. Is ETACS-ECU connector C-312 in good condition?

YES Go to Step 7.
NO Repair the damaged parts.
STEP 7. Check the wiring harness between headlight relay (HIGH) connector A-21X (terminal 1) and ETACS-ECU connector C-312 (terminal 13).

- Check the ground wires for open circuit.

Q. Is the wiring harness between headlight relay (HIGH) connector A-21X (terminal 1) and ETACS-ECU connector C-312 (terminal 13) in good condition?

YES Go to Step 9.
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. Verify that the high-beam headlights illuminate normally.
STEP 8. Check the wiring harness between headlight relay (HIGH) connector A-21X (terminal 2 or 4) and the fusible link (36).

- Check the power supply line for open circuit.

Q. Is the wiring harness between headlight relay (HIGH) connector A-21X (terminal 2 or 4) and fusible link (36) in good condition?

YES Go to Step 9.
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. Verify that the high-beam headlights illuminate normally.
STEP 9. Retest the system

Q. Do the headlights (high-beam) illuminate in good condition?

YES The trouble can be an intermittent malfunction How to Cope With Intermittent Malfunctions).
NO Replace the ETACS-ECU.