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


caution Whenever the ECU is replaced, ensure that the power supply circuit, the earth circuit and the communication circuit are normal.








COMMENTS ON TROUBLE SYMPTOM



PROBABLE CAUSES



  • Malfunction of column switch
  • Malfunction of headlamp relay (LO)
  • Malfunction of the ETACS-ECU
  • Damaged harness wires and connectors

DIAGNOSIS PROCEDURE


STEP 1. M.U.T.-III diagnosis code



Q. Is the diagnosis code set?





STEP 2. M.U.T.-III data list




  • Headlamp switch to ON.
Item No.
 Item name
 Normal condition
Item 341
 Head lamp switch
 ON
OK: Normal condition is displayed.

Q. Is the check result normal?





STEP 3. Connector check: A-28X Headlamp relay (LO) connector


Q. Is the check result normal?





STEP 4. Headlamp relay (LO) check



Q. Is the check result normal?





STEP 5. Voltage measurement at the A-28X headlamp relay (LO) connector


(1)Remove the headlamp relay (LO), and measure at the relay box side.
(2)Measure the voltage between headlamp relay (LO) connector terminal No. 2/4 and the body earth.
OK: System voltage

Q. Is the check result normal?





STEP 6. Connector check: C-312 ETACS-ECU connector


Q. Is the check result normal?





STEP 7. Wiring harness check between the A-28X headlamp relay (LO) connector terminal No. 1 and the C-312 ETACS-ECU connector terminal No. 6



  • Check the output lines for open circuit.

Q. Is the check result normal?





STEP 8. Wiring harness check between the A-28X headlamp relay (LO) connector terminal No. 2/4 and the fusible link (34)



  • Check the output lines for open circuit.

Q. Is the check result normal?





STEP 9. Retest the system



Q. Is the check result normal?