Mitsubishi Lancer (4A9 engine). Manual - part 114
HEADLAMP
CHASSIS ELECTRICAL
54A-118
Inspection Procedure 8: The auto lamp function does not work normally.
CAUTION
Whenever the ECU is replaced, ensure that the
power supply circuit, the earth circuit and the
communication circuit are normal.
OPERATION
The ETACS-ECU operates this function in accord-
ance with the input signals from driving distance,
lighting control sensor, and column switch (auto lamp
switch). Also, when the column switch (lighting
switch) is in the "AUTO" position, and when an
abnormality is present to the auto lamp circuit, the
fail-safe function is activated and the low beam is
turned ON at all times regardless of the brightness
around the vehicle.
COMMENTS ON TROUBLE SYMPTOM
If the auto lamp function does not work normally, the
above input signal circuit(s) or the ETACS-ECU may
have a problem.
PROBABLE CAUSES
• Malfunction of the lighting control sensor
• Malfunction of the column switch
• Malfunction of the ETACS-ECU
• Damaged harness wires and connectors
DIAGNOSIS PROCEDURE
STEP 1. M.U.T.-III CAN bus diagnostics
Use the M.U.T.-III to diagnose the CAN bus lines.
Q: Is the check result normal?
YES :
Go to Step 2.
NO :
Repair the CAN bus line (Refer to GROUP
54C
− Troubleshooting ).
STEP 2. M.U.T.-III diagnosis code
Check if diagnosis code is set to the LIN.
Q: Is the diagnosis code set?
YES :
Refer to diagnosis code chart .
NO :
Go to Step 3.
STEP 3. M.U.T.-III other system diagnosis code
Check if diagnosis code is set to the ETACS-ECU.
Q: Is the diagnosis code set?
YES :
Troubleshoot the ETACS-ECU (Refer to ).
NO :
Go to Step 4.
STEP 4. Check that the headlamps operate.
Check that the headlamps (low-beam) illuminate nor-
mally.
Q: Is the check result normal?
YES :
Go to Step 5.
NO :
Refer to Inspection Procedure 1 "None of
the low-beam headlamps illuminate." .
STEP 5. M.U.T.-III data list
Use the ETACS-ECU service data to check the sig-
nals related to the operation of auto lamp function.
• Turn the lighting switch to the "AUTO" position.
OK: Normal condition is displayed.
Q: Is the check result normal?
YES :
Go to Step 6.
NO :
Troubleshoot the ETACS-ECU. Refer to
Inspection Procedure 11 "The column
switch signal is not received" .
STEP 6. Lighting control sensor check
Check the lighting control sensor. Refer to .
Q: Is the check result normal?
YES :
Go to Step 7.
NO :
Replace the lighting control sensor.
STEP 7. Retest the system
Check that the auto lamp function works normally.
Q: Is the check result normal?
YES :
The trouble can be an intermittent
malfunction (Refer to GROUP 00
− How to
use Troubleshooting/inspection Service
Points
− How to Cope with Intermittent
Malfunction ).
NO :
Replace the ETACS-ECU.
Item No.
Item name
Normal
condition
Item 348
Headlamp
switch (auto)
ON