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Inspection Procedure 8: The auto light function does not work normally.
 
 
cautionBefore replacing the ECU, ensure that the power supply circuit, the ground circuit and the communication circuit are normal.
 
 
 
 
OPERATION
The ETACS-ECU operates this function in accordance with the input signals from driving distance, lighting control sensor, and column switch (auto light switch). Also, when the column switch (lighting switch) is in the "AUTO" position, and when an abnormality is present to the auto light circuit, the fail-safe function is activated and the low beam is turned ON at all times regardless of the brightness around the vehicle.
 
 
TECHNICAL DESCRIPTION (COMMENT)
If the auto light function does not work normally, the above input signal circuit(s) or the ETACS-ECU may have a problem.
 
 
TROUBLESHOOTING HINTS
  • The lighting control sensor 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
STEP 1. Using scan tool (M.U.T.-IIISE), diagnose the CAN bus line.
(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 the Scan Tool (M.U.T.-IIISE) ."
(2) Press the electric motor switch to turn on the power supply mode.
(3) Diagnose the CAN bus line.
(4) Press the electric motor switch to turn off the power supply mode.
Is the CAN bus line found to be normal?
Go to Step 2.
Repair the CAN bus line (Refer to GROUP 54C - Diagnosis ).
 
STEP 2. Using scan tool (M.U.T.-IIISE), read the LIN DTC.
Check if DTC is set in the LIN.
Is the DTC set?
Refer to DTC chart .
Go to Step 3.
 
STEP 3. Using scan tool (M.U.T.-IIISE), read the ETACS DTC.
Check if DTC is set in the ETACS-ECU.
Is the DTC set?
Troubleshoot the ETACS-ECU (Refer to ).
Go to Step 4.
 
STEP 4. Check that the headlights operate.
Check that the headlights (low-beam) illuminate normally.
Is the check result normal?
Go to Step 5.
Refer to Inspection Procedure 1 "None of the low-beam headlights illuminate." .
 
STEP 5. Using scan tool (M.U.T.-IIISE), check data list.
Use the ETACS-ECU service data to check the signals related to the operation of auto light function.
  • Turn the lighting switch to the "AUTO" position.
 
Item No.Item nameNormal condition
Item 348Headlight switch (Auto)ON
OK: Normal condition is displayed.
Is the check result normal?
Go to Step 6.
Troubleshoot the ETACS-ECU. Refer to Inspection Procedure 10 "The column switch signal is not received ."
 
STEP 6. Lighting control sensor check.
Check the lighting control sensor. Refer to .
Is the check result normal?
Go to Step 7.
Replace the lighting control sensor.
 
STEP 7. Retest the system.
Check that the auto light function works 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.