Inspection Procedure H-8
INSPECTION PROCEDURE H-8: Headlight and Taillight: The High-beam indicator light does not illuminate.NOTE: This troubleshooting procedure requires the use of scan tool MB991958 and SWS monitor kit MB991813. For details on how to use the SWS monitor, refer to "How to use SWS monitor." How to Use SWS Monitor
High-Beam Indicator Light Circuit:
CIRCUIT OPERATION
At the same time that the high beams are illuminated, the ETACS-ECU sends a signal to illuminate the high beam indicator via the CAN bus line.
TECHNICAL DESCRIPTION (COMMENT)
If the high beam indicator does not illuminate normally, connector(s), wiring harness in the CAN bus lines, the ETACS-ECU or the combination meter may be defective.
TROUBLESHOOTING HINTS
- The wiring harness or connectors may have loose, corroded, or damaged terminals, or terminals pushed back in the connector
- The combination meter may be defective
- The ETACS-ECU may be defective
DIAGNOSIS
Required Special Tools:
- MB991223: Harness Set
- MB992006: Extra Fine Probe
- MB991958: Scan Tool (M.U.T.-III Sub Assembly)
- MB991824: V.C.I.
- MB991827: M.U.T.-III USB Cable
- MB991910: M.U.T.-III Main Harness A
- MB991813: SWS Monitor Kit
- MB991806: SWS Monitor Cartridge
- MB991812: SWS Monitor Harness (For Column-ECU)
- MB991822: Probe Harness
STEP 1. Check the headlights.
When the lighting switch is operated, check that the headlights illuminate/go off normally.
Q: Are the headlights in good condition?
YES : Go to Step 2.
NO : First, repair the headlights. Refer to Inspection Procedure H-7 "One of the headlights does not illuminate [2-bulb type]" 2-Bulb Type or "One of the headlights does not illuminate [4-bulb type]." 4-Bulb Type
STEP 2. Using scan tool MB991958, diagnose the CAN bus line.
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.
1. Connect scan tool MB991958. Refer to "How to connect SWS monitor." How to Connect SWS Monitor
2. Turn the ignition switch to the "ON" position.
3. Diagnose the CAN bus line.
4. Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the CAN bus line found to be normal?
YES : Go to Step 3.
NO : Repair the CAN bus line
STEP 3. Using scan tool MB991958, read the combination meter diagnostic trouble code.
Check whether a combination meter-related DTC is set.
1. Turn the ignition switch to the "ON" position.
2. Check whether the combination meter-related DTC is set.
3. Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the DTC set?
YES : Diagnose the combination meter. Refer to Diagnosis. Diagnostic Trouble Code Descriptions
NO : Go to Step 4.
STEP 4. Use scan tool MB991958 to select "ECU COMM Check" on the SWS monitor display.
Check the ETACS-ECU.
CAUTION: Connect special tool MB991910 before connecting special tool MB991812. Be sure to connect special tool MB991806 after turning on special tool MB991824.
1. Connect the SWS monitor. Refer to "How to connect SWS monitor." How to Connect SWS Monitor
2. Turn the ignition switch to the "LOCK" (OFF) position.
3. Operate scan tool MB991958 according to the procedure below to display "ECU COMM Check."
a. Select "Interactive Diagnosis."
b. Select "System select."
c. Select "SWS."
d. Select "SWS MONITOR."
e. Select "ECU COMM Check."
4. Scan tool MB991958 should show "OK" on the "ECU COMM Check" menu for the "ETACS ECU" menu.
Q: Is "OK" displayed for the "ETACS ECU" menu?
YES : Go to Step 5.
NO : Refer to Inspection Procedure A-3 "Communication with the ETACS-ECU is not possible." Inspection Procedure A-3
STEP 5. Replace the combination meter.
1. Replace the combination meter.
2. Check that the high beam indicator light illuminates normally.
Q: Does the high beam indicator light illuminate normally?
YES : No action is necessary and testing is complete.
NO : Replace the ETACS-ECU. When the ETACS-ECU is replaced, register the encrypted code. Check that the high beam indicator light illuminates normally.