Inspection Procedure 1: The Low-beam Headlamps do not Illuminate Normally.


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




COMMENTS ON TROUBLE SYMPTOM


If the low-beam headlamps do not illuminate, the headlamp switch input circuit or the front-ECU may be defective.

PROBABLE CAUSES



DIAGNOSIS PROCEDURE


STEP 1. Pulse check


Check the input signal from the headlamp switch.
System switch
 Check condition
Ignition switch (IG1)
 When turned from ACC to ON
Headlamp switch
 When the lighting switch is turned to the HEADLAMP position
OK: The M.U.T.-III sounds or the voltmeter needle fluctuates.

Q. Are the check result normal?

YES (All the signals are received normally) : Go to Step 2.

NO (The ignition switch (IG1) signal is not received) : Refer to ETACS - Input Signal Chart .

NO (The headlamp switch signal is not received) : Refer to ETACS - Input Signal Chart .

STEP 2. Connector check: A-08X front-ECU connector


Q. Is the check result normal?

Go to Step 3.

Repair the defective connector.

STEP 3. Voltage measurement at A-08X front-ECU connector.


(1)Remove the front-ECU, and measure at the relay box side.
(2)Voltage between A-08X front-ECU connector terminal Nos.3, 4, 5 and body earth
OK: System voltage

Q. Is the check result normal?

Go to Step 5.

Go to Step 4.

STEP 4. Check the wiring harness between A-08X front-ECU connector terminal Nos.3, 4, 5 and the battery.



Q. Is the check result normal?

The trouble can be an intermittent malfunction (Refer to GROUP 00 - How to Cope with Intermittent Malfunction ).

Repair the wiring harness.

STEP 5. Retest the system.


Check that the low-beam headlamps illuminate 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 front-ECU.