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Inspection Procedure 1: None of the low-beam headlights illuminate.
 
 
cautionBefore replacing the ECU, ensure that the power supply circuit, the ground circuit and the communication circuit are normal.
 
 
 
 
TECHNICAL DESCRIPTION (COMMENT)
If both headlights (low-beam) do not illuminate normally, the headlight switch input circuit, headlight relay (LOW), or ETACS-ECU may have a problem.
 
 
TROUBLESHOOTING HINTS
  • The headlight relay (LOW) may be defective
  • The column switch 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 Tools:
  • MB992006: Extra fine probe
  • MB991223: Harness set
STEP 1. Using scan tool (M.U.T.-IIISE), read the DTC.
(1)
cautionTo prevent damage to scan tool (M.U.T.-IIISE), always turn off the power supply mode of the electric motor switch before connecting or disconnecting scan tool (M.U.T.-IIISE).
Connect scan tool (M.U.T.-IIISE). Refer to "How to connect Scan Tool (M.U.T.-IIISE) ."
(2) Press the electric motor switch to turn on the power supply mode.
(3) Check whether the ETACS-ECU related DTC is set.
(4) Press the electric motor switch to turn off the power supply mode.
Is the DTC set?
Troubleshoot the ETACS-ECU. Refer to .
Go to Step 2.
 
STEP 2. Using scan tool (M.U.T.-IIISE), check data list.
Use the ETACS-ECU service data to check the signal related to the operation of headlight function.
  • Headlight switch to ON.
 
Item No.Item nameNormal condition
Item 341Head light switchON
OK: Normal condition is displayed.
Is the check result normal?
Go to Step 3.
Troubleshoot the ETACS-ECU. Refer to Inspection Procedure 10 "The column switch signal is not received ."
 
STEP 3. Headlight relay (LOW) check.
Refer to .
Is the check result normal?
Go to Step 4.
Replace the headlight relay (LOW).
 
STEP 4. Voltage measurement at the headlight relay (LOW) connector.
(1) Remove the headlight relay (LOW), and measure at the relay box side.
(2) Measure the voltage between headlight relay (LOW) connector (power supply terminal) and ground.
OK: The voltage should measure approximately 12 volts (battery positive voltage).
Is the check result normal?
Go to Step 5.
Go to Step 6.
 
STEP 5. Check of open circuit in HLO line between ETACS-ECU connector and headlight relay (LOW) connector.
Is the check result normal?
Go to Step 7.
Repair the connector(s) or wiring harness.
 
STEP 6. Check of open circuit in power supply line between fusible link and headlight relay (LOW) connector.
Is the check result normal?
Go to Step 7.
Repair the connector(s) or wiring harness.
 
STEP 7. Retest the system.
Check that the headlights (low-beam) illuminate normally.
Is the check result normal?
The trouble can be an intermittent malfunction (Refer to GROUP 00 - How to use Troubleshooting/inspection Service Points - How to Cope with Intermittent Malfunction ).
Replace the ETACS-ECU.