Inspection Procedure J-3

Headlight and Taillight: Headlights (high-beam) do not illuminate normally.

NOTE: This troubleshooting procedure requires the use of scan tool MB991502 and SWS monitor kit MB991862. For details on how to use the SWS monitor, refer to "How to use SWS monitor."

Headlight Relay (High-beam) Circuit:

CIRCUIT OPERATION
When the dimmer switch is turned on, the column switch sends a signal to the front-ECU. Then the front-ECU switches the headlights from low-beam to high beam or vice versa.

TECHNICAL DESCRIPTION (COMMENT)
If the headlights (high beam) do not illuminate normally, the column switch or the front-ECU may be defective.

TROUBLESHOOTING HINTS
- The column switch (turn-signal light and lighting switch) may be defective
- The front-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 Tools:
- MB991223: Harness Set
- MB991502: Scan Tool (MUT-II)
- MB991862: SWS monitor kit

STEP 1. Use scan tool MB991502 to select "ECU COMM CHK" on the SWS monitor display.

Check the following ECUs:
- Column-ECU
- Front-ECU

CAUTION: To prevent damage to scan tool MB991502, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991502. Connect the DLC harness before connecting the column-ECU harness. Be sure to connect SWS monitor kit MB991862 after turning on scan tool MB991502.




1. Connect scan tool MB991502 to the data link connector.
2. Connect SWS monitor kit MB991862 to the column switch connector.
3. Turn the ignition switch to the "LOCK" (OFF) position.
4. Operate scan tool MB991502 according to the procedure below to display "ECU COMM CHK."
1. Select "SYSTEM SELECT."
2. Select "SWS."
3. Select "SWS MONITOR."
4. Select "ECU COMM CHK."




5. Scan tool MB991502 should show "OK" on the "ECU COMM CHK" menus for both the "COLUMN ECU" and the "FRONT ECU" menus.

Q: Is "OK" displayed on both the "COLUMN ECU" and "FRONT ECU" menus?
"OK" are displayed for all the items : Go to Step 2.
"NG" is displayed on the "COLUMN ECU" menu : Refer to Inspection Procedure A-2 "Communication with column switch (column-ECU) is not possible."
"NG" is displayed on the "FRONT ECU" menu : Refer to Inspection procedure A-4 "Communication with front-ECU is not possible."

STEP 2. Check the input signal by using "FUNCTION DIAG." menu of the SWS monitor.

Check the input signals from the following switches:
- Ignition switch: ON
- Lighting switch: HEAD
- Dimmer switch: ON







Operate scan tool MB991502 according to the procedure below to display "HEADLIGHT HI."
1. Select "SYSTEM SELECT."
2. Select "SWS."
3. Select "SWS MONITOR."
4. Select "FUNCTION DIAG."
5. Select "LIGHTING."
6. Select "HEADLIGHT HI."




Check that normal conditions are displayed on the items described in the table.

Q: Are normal conditions displayed on the "HEADLIGHT SW", "DIMMER SW", "H/L AUTO-CUT" and "FRONT ECU ACK"?

YES: Replace the front-ECU. Verify that the headlights (high-beam) illuminate normally.

NO:
- Normal condition is not displayed on the "HEADLIGHT SW": Refer to Inspection Procedure M-5 "ETACS-ECU does not receive a signal from the headlight switch."
- Normal condition is not displayed on the "DIMMER SW": Refer to Inspection Procedure M-5 "ETACS-ECU does not receive a signal from the dimmer switch."
- Normal condition is not displayed on the "H/L AUTO-CUT": Refer to Inspection Procedure J-9 "Headlight automatic shutdown function does not work normally."
- Normal condition is not displayed on the "FRONT ECU ACK": Replace the front-ECU. Verify that the headlights (high-beam) illuminate normally.