Inspection Procedure K-6: The auto lamp function does not work normally.


caution Whenever the ECU is replaced, ensure that the input and output signal circuits are normal.


COMMENTS ON TROUBLE SYMPTOM
If auto lamp function does not work normally, the above input signal circuit(s) or the ETACS-ECU may be defective.

POSSIBLE CAUSES

  • Malfunction of the ETACS-ECU
  • Malfunction of the front-ECU
  • Damaged harness wires and connectors

DIAGNOSIS PROCEDURE

Step 1. Check that the taillights and headlamps operate.
Check that the tail lights and headlamps illuminate normally.

Q. Is the check result normal?
Go to Step 2.
Check the taillights and the headlamps (Refer to trouble symptom chart ).

Step 2. Pulse check
Check the input signals below, which are related to the auto-lamp function.
System switch
 Check condition
Ignition switch (IG1)
 When turned from ACC to ON
Photo sensor
 When the lighting in the vicinity of the sensor goes darker
Vehicle speed signal
 When the vehicle speed has reached 10 km/h or more.
OK: The M.U.T.-III sounds or the voltmeter needle fluctuates.

Q. Is the check result normal?
All the signals are received normally. : Go to Step 3.
The ignition switch (IG1) signal is not received. : Refer to Inspection Procedure P-2 "The ignition switch (IG1) signal is not received ."
The photo sensor signal is not received. : Refer to inspection procedure P-20 "No photo sensor signal is received ."
The speed signal is not received. : Refer to Inspection Procedure P-22 "The vehicle speed signal is not received ."

Step 3. Retest the system.
Check that the auto lamp function works normally.

Q. Is the check result normal?
The trouble can be an intermittent malfunction (Refer to GROUP 00 - How to Cope with Intermittent Malfunction ).
Replace the ETACS-ECU.